Auto merge of #55382 - kennytm:rollup, r=kennytm

Rollup of 21 pull requests

Successful merges:

 - #54816 (Don't try to promote already promoted out temporaries)
 - #54824 (Cleanup rustdoc tests with `@!has` and `@!matches`)
 - #54921 (Add line numbers option to rustdoc)
 - #55167 (Add a "cheap" mode for `compute_missing_ctors`.)
 - #55258 (Fix Rustdoc ICE when checking blanket impls)
 - #55264 (Compile the libstd we distribute with -Ccodegen-unit=1)
 - #55271 (Unimplement ExactSizeIterator for MIR traversing iterators)
 - #55292 (Macro diagnostics tweaks)
 - #55298 (Point at macro definition when no rules expect token)
 - #55301 (List allowed tokens after macro fragments)
 - #55302 (Extend the impl_stable_hash_for! macro for miri.)
 - #55325 (Fix link to macros chapter)
 - #55343 (rustbuild: fix remap-debuginfo when building a release)
 - #55346 (Shrink `Statement`.)
 - #55358 (Remove redundant clone (2))
 - #55370 (Update mailmap for estebank)
 - #55375 (Typo fixes in configure_cmake comments)
 - #55378 (rustbuild: use configured linker to build boostrap)
 - #55379 (validity: assert that unions are non-empty)
 - #55383 (Use `SmallVec` for the queue in `coerce_unsized`.)
 - #55391 (bootstrap: clean up a few clippy findings)

.mailmap

@@ -78,6 +78,7 @@ Eric Holk <eric.holk@gmail.com> <eholk@mozilla.com>
 Eric Holmes <eric@ejholmes.net>
 Eric Reed <ecreed@cs.washington.edu> <ereed@mozilla.com>
 Erick Tryzelaar <erick.tryzelaar@gmail.com> <etryzelaar@iqt.org>
+Esteban Küber <esteban@kuber.com.ar> <estebank@users.noreply.github.com> <esteban@commure.com> <github@kuber.com.ar>
 Evgeny Sologubov
 Falco Hirschenberger <falco.hirschenberger@gmail.com> <hirschen@itwm.fhg.de>
 Felix S. Klock II <pnkfelix@pnkfx.org> Felix S Klock II <pnkfelix@pnkfx.org>

RELEASES.md

@@ -98,7 +98,7 @@ Misc
 [cargo/5877]: https://github.com/rust-lang/cargo/pull/5877/
 [cargo/5878]: https://github.com/rust-lang/cargo/pull/5878/
 [cargo/5995]: https://github.com/rust-lang/cargo/pull/5995/
-[proc-macros]: https://doc.rust-lang.org/book/2018-edition/ch19-06-macros.html
+[proc-macros]: https://doc.rust-lang.org/nightly/book/2018-edition/ch19-06-macros.html
 
 [`Ipv4Addr::BROADCAST`]: https://doc.rust-lang.org/nightly/std/net/struct.Ipv4Addr.html#associatedconstant.BROADCAST
 [`Ipv4Addr::LOCALHOST`]: https://doc.rust-lang.org/nightly/std/net/struct.Ipv4Addr.html#associatedconstant.LOCALHOST

config.toml.example

@@ -277,6 +277,10 @@
 # compiler.
 #codegen-units = 1
 
+# Sets the number of codegen units to build the standard library with,
+# regardless of what the codegen-unit setting for the rest of the compiler is.
+#codegen-units-std = 1
+
 # Whether or not debug assertions are enabled for the compiler and standard
 # library. Also enables compilation of debug! and trace! logging macros.
 #debug-assertions = false

src/bootstrap/bootstrap.py

@@ -632,6 +632,9 @@ class RustBuild(object):
             target_features += ["-crt-static"]
         if target_features:
             env["RUSTFLAGS"] += "-C target-feature=" + (",".join(target_features)) + " "
+        target_linker = self.get_toml("linker", build_section)
+        if target_linker is not None:
+            env["RUSTFLAGS"] += "-C linker=" + target_linker + " "
 
         env["PATH"] = os.path.join(self.bin_root(), "bin") + \
             os.pathsep + env["PATH"]

src/bootstrap/builder.rs

@@ -1119,10 +1119,15 @@ impl<'a> Builder<'a> {
             cargo.arg("-v");
         }
 
-        // This must be kept before the thinlto check, as we set codegen units
-        // to 1 forcibly there.
-        if let Some(n) = self.config.rust_codegen_units {
-            cargo.env("RUSTC_CODEGEN_UNITS", n.to_string());
+        match (mode, self.config.rust_codegen_units_std, self.config.rust_codegen_units) {
+            (Mode::Std, Some(n), _) |
+            (Mode::Test, Some(n), _) |
+            (_, _, Some(n)) => {
+                cargo.env("RUSTC_CODEGEN_UNITS", n.to_string());
+            }
+            _ => {
+                // Don't set anything
+            }
         }
 
         if self.config.rust_optimize {

src/bootstrap/compile.rs

@@ -69,7 +69,7 @@ impl Step for Std {
         if builder.config.keep_stage.contains(&compiler.stage) {
             builder.info("Warning: Using a potentially old libstd. This may not behave well.");
             builder.ensure(StdLink {
-                compiler: compiler,
+                compiler,
                 target_compiler: compiler,
                 target,
             });
@@ -358,7 +358,7 @@ impl Step for Test {
         if builder.config.keep_stage.contains(&compiler.stage) {
             builder.info("Warning: Using a potentially old libtest. This may not behave well.");
             builder.ensure(TestLink {
-                compiler: compiler,
+                compiler,
                 target_compiler: compiler,
                 target,
             });
@@ -480,7 +480,7 @@ impl Step for Rustc {
         if builder.config.keep_stage.contains(&compiler.stage) {
             builder.info("Warning: Using a potentially old librustc. This may not behave well.");
             builder.ensure(RustcLink {
-                compiler: compiler,
+                compiler,
                 target_compiler: compiler,
                 target,
             });
@@ -816,8 +816,8 @@ fn copy_codegen_backends_to_sysroot(builder: &Builder,
         let filename = file.file_name().unwrap().to_str().unwrap();
         // change `librustc_codegen_llvm-xxxxxx.so` to `librustc_codegen_llvm-llvm.so`
         let target_filename = {
-            let dash = filename.find("-").unwrap();
-            let dot = filename.find(".").unwrap();
+            let dash = filename.find('-').unwrap();
+            let dot = filename.find('.').unwrap();
             format!("{}-{}{}",
                     &filename[..dash],
                     backend,

src/bootstrap/config.rs

@@ -95,6 +95,7 @@ pub struct Config {
     // rust codegen options
     pub rust_optimize: bool,
     pub rust_codegen_units: Option<u32>,
+    pub rust_codegen_units_std: Option<u32>,
     pub rust_debug_assertions: bool,
     pub rust_debuginfo: bool,
     pub rust_debuginfo_lines: bool,
@@ -294,6 +295,7 @@ impl Default for StringOrBool {
 struct Rust {
     optimize: Option<bool>,
     codegen_units: Option<u32>,
+    codegen_units_std: Option<u32>,
     debug_assertions: Option<bool>,
     debuginfo: Option<bool>,
     debuginfo_lines: Option<bool>,
@@ -580,6 +582,8 @@ impl Config {
                 Some(n) => config.rust_codegen_units = Some(n),
                 None => {}
             }
+
+            config.rust_codegen_units_std = rust.codegen_units_std;
         }
 
         if let Some(ref t) = toml.target {

src/bootstrap/configure.py

@@ -393,6 +393,13 @@ for target in configured_targets:
     targets[target][0] = targets[target][0].replace("x86_64-unknown-linux-gnu", target)
 
 
+def is_number(value):
+  try:
+    float(value)
+    return True
+  except:
+    return False
+
 # Here we walk through the constructed configuration we have from the parsed
 # command line arguments. We then apply each piece of configuration by
 # basically just doing a `sed` to change the various configuration line to what
@@ -406,7 +413,11 @@ def to_toml(value):
     elif isinstance(value, list):
         return '[' + ', '.join(map(to_toml, value)) + ']'
     elif isinstance(value, str):
-        return "'" + value + "'"
+        # Don't put quotes around numeric values
+        if is_number(value):
+            return value
+        else:
+            return "'" + value + "'"
     else:
         raise RuntimeError('no toml')
 

src/bootstrap/dist.rs

@@ -1447,8 +1447,8 @@ impl Step for Extended {
         tarballs.extend(rls_installer.clone());
         tarballs.extend(clippy_installer.clone());
         tarballs.extend(rustfmt_installer.clone());
-        tarballs.extend(llvm_tools_installer.clone());
-        tarballs.extend(lldb_installer.clone());
+        tarballs.extend(llvm_tools_installer);
+        tarballs.extend(lldb_installer);
         tarballs.push(analysis_installer);
         tarballs.push(std_installer);
         if builder.config.docs {

src/bootstrap/flags.rs

@@ -93,8 +93,7 @@ impl Default for Subcommand {
 impl Flags {
     pub fn parse(args: &[String]) -> Flags {
         let mut extra_help = String::new();
-        let mut subcommand_help = format!(
-            "\
+        let mut subcommand_help = String::from("\
 Usage: x.py <subcommand> [options] [<paths>...]
 
 Subcommands:
@@ -365,8 +364,8 @@ Arguments:
         }
 
         let cmd = match subcommand.as_str() {
-            "build" => Subcommand::Build { paths: paths },
-            "check" => Subcommand::Check { paths: paths },
+            "build" => Subcommand::Build { paths },
+            "check" => Subcommand::Check { paths },
             "test" => Subcommand::Test {
                 paths,
                 bless: matches.opt_present("bless"),
@@ -386,9 +385,9 @@ Arguments:
                 paths,
                 test_args: matches.opt_strs("test-args"),
             },
-            "doc" => Subcommand::Doc { paths: paths },
+            "doc" => Subcommand::Doc { paths },
             "clean" => {
-                if paths.len() > 0 {
+                if !paths.is_empty() {
                     println!("\nclean does not take a path argument\n");
                     usage(1, &opts, &subcommand_help, &extra_help);
                 }
@@ -413,11 +412,11 @@ Arguments:
             keep_stage: matches.opt_strs("keep-stage")
                 .into_iter().map(|j| j.parse().unwrap())
                 .collect(),
-            host: split(matches.opt_strs("host"))
+            host: split(&matches.opt_strs("host"))
                 .into_iter()
                 .map(|x| INTERNER.intern_string(x))
                 .collect::<Vec<_>>(),
-            target: split(matches.opt_strs("target"))
+            target: split(&matches.opt_strs("target"))
                 .into_iter()
                 .map(|x| INTERNER.intern_string(x))
                 .collect::<Vec<_>>(),
@@ -425,7 +424,7 @@ Arguments:
             jobs: matches.opt_str("jobs").map(|j| j.parse().unwrap()),
             cmd,
             incremental: matches.opt_present("incremental"),
-            exclude: split(matches.opt_strs("exclude"))
+            exclude: split(&matches.opt_strs("exclude"))
                 .into_iter()
                 .map(|p| p.into())
                 .collect::<Vec<_>>(),
@@ -488,7 +487,7 @@ impl Subcommand {
     }
 }
 
-fn split(s: Vec<String>) -> Vec<String> {
+fn split(s: &[String]) -> Vec<String> {
     s.iter()
         .flat_map(|s| s.split(','))
         .map(|s| s.to_string())

src/bootstrap/lib.rs

@@ -765,10 +765,10 @@ impl Build {
 
         let path = match which {
             GitRepo::Rustc => {
-                let sha = self.rust_info.sha().expect("failed to find sha");
+                let sha = self.rust_sha().unwrap_or(channel::CFG_RELEASE_NUM);
                 format!("/rustc/{}", sha)
             }
-            GitRepo::Llvm => format!("/rustc/llvm"),
+            GitRepo::Llvm => String::from("/rustc/llvm"),
         };
         Some(format!("{}={}", self.src.display(), path))
     }
@@ -783,7 +783,7 @@ impl Build {
     fn cflags(&self, target: Interned<String>, which: GitRepo) -> Vec<String> {
         // Filter out -O and /O (the optimization flags) that we picked up from
         // cc-rs because the build scripts will determine that for themselves.
-        let mut base = self.cc[&target].args().iter()
+        let mut base: Vec<String> = self.cc[&target].args().iter()
                            .map(|s| s.to_string_lossy().into_owned())
                            .filter(|s| !s.starts_with("-O") && !s.starts_with("/O"))
                            .collect::<Vec<_>>();
@@ -806,10 +806,10 @@ impl Build {
         if let Some(map) = self.debuginfo_map(which) {
         let cc = self.cc(target);
             if cc.ends_with("clang") || cc.ends_with("gcc") {
-                base.push(format!("-fdebug-prefix-map={}", map).into());
+                base.push(format!("-fdebug-prefix-map={}", map));
             } else if cc.ends_with("clang-cl.exe") {
                 base.push("-Xclang".into());
-                base.push(format!("-fdebug-prefix-map={}", map).into());
+                base.push(format!("-fdebug-prefix-map={}", map));
             }
         }
         base

src/bootstrap/native.rs

@@ -353,7 +353,7 @@ fn configure_cmake(builder: &Builder,
        // definitely causes problems since all the env vars are pointing to
        // 32-bit libraries.
        //
-       // To hack aroudn this... again... we pass an argument that's
+       // To hack around this... again... we pass an argument that's
        // unconditionally passed in the sccache shim. This'll get CMake to
        // correctly diagnose it's doing a 32-bit compilation and LLVM will
        // internally configure itself appropriately.
@@ -361,7 +361,7 @@ fn configure_cmake(builder: &Builder,
            cfg.env("SCCACHE_EXTRA_ARGS", "-m32");
        }
 
-    // If ccache is configured we inform the build a little differently hwo
+    // If ccache is configured we inform the build a little differently how
     // to invoke ccache while also invoking our compilers.
     } else if let Some(ref ccache) = builder.config.ccache {
        cfg.define("CMAKE_C_COMPILER", ccache)

src/bootstrap/sanity.rs

@@ -74,7 +74,7 @@ pub fn check(build: &mut Build) {
     // one is present as part of the PATH then that can lead to the system
     // being unable to identify the files properly. See
     // https://github.com/rust-lang/rust/issues/34959 for more details.
-    if cfg!(windows) && path.to_string_lossy().contains("\"") {
+    if cfg!(windows) && path.to_string_lossy().contains('\"') {
         panic!("PATH contains invalid character '\"'");
     }
 

src/bootstrap/test.rs

@@ -521,7 +521,7 @@ impl Step for RustdocTheme {
     fn make_run(run: RunConfig) {
         let compiler = run.builder.compiler(run.builder.top_stage, run.host);
 
-        run.builder.ensure(RustdocTheme { compiler: compiler });
+        run.builder.ensure(RustdocTheme { compiler });
     }
 
     fn run(self, builder: &Builder) {
@@ -584,9 +584,9 @@ impl Step for RustdocJS {
             });
             builder.run(&mut command);
         } else {
-            builder.info(&format!(
+            builder.info(
                 "No nodejs found, skipping \"src/test/rustdoc-js\" tests"
-            ));
+            );
         }
     }
 }
@@ -653,7 +653,7 @@ impl Step for Tidy {
         }
 
         let _folder = builder.fold_output(|| "tidy");
-        builder.info(&format!("tidy check"));
+        builder.info("tidy check");
         try_run(builder, &mut cmd);
     }
 
@@ -1052,7 +1052,7 @@ impl Step for Compiletest {
         let hostflags = flags.clone();
         cmd.arg("--host-rustcflags").arg(hostflags.join(" "));
 
-        let mut targetflags = flags.clone();
+        let mut targetflags = flags;
         targetflags.push(format!(
             "-Lnative={}",
             builder.test_helpers_out(target).display()
@@ -1168,9 +1168,9 @@ impl Step for Compiletest {
             }
         }
         if suite == "run-make-fulldeps" && !builder.config.llvm_enabled {
-            builder.info(&format!(
+            builder.info(
                 "Ignoring run-make test suite as they generally don't work without LLVM"
-            ));
+            );
             return;
         }
 
@@ -1692,10 +1692,10 @@ impl Step for Crate {
             // The javascript shim implements the syscall interface so that test
             // output can be correctly reported.
             if !builder.config.wasm_syscall {
-                builder.info(&format!(
+                builder.info(
                     "Libstd was built without `wasm_syscall` feature enabled: \
                      test output may not be visible."
-                ));
+                );
             }
 
             // On the wasm32-unknown-unknown target we're using LTO which is
@@ -1891,7 +1891,7 @@ impl Step for Distcheck {
 
     /// Run "distcheck", a 'make check' from a tarball
     fn run(self, builder: &Builder) {
-        builder.info(&format!("Distcheck"));
+        builder.info("Distcheck");
         let dir = builder.out.join("tmp").join("distcheck");
         let _ = fs::remove_dir_all(&dir);
         t!(fs::create_dir_all(&dir));
@@ -1919,7 +1919,7 @@ impl Step for Distcheck {
         );
 
         // Now make sure that rust-src has all of libstd's dependencies
-        builder.info(&format!("Distcheck rust-src"));
+        builder.info("Distcheck rust-src");
         let dir = builder.out.join("tmp").join("distcheck-src");
         let _ = fs::remove_dir_all(&dir);
         t!(fs::create_dir_all(&dir));

src/bootstrap/tool.rs

@@ -148,7 +148,7 @@ impl Step for ToolBuild {
             }
         });
 
-        if is_expected && duplicates.len() != 0 {
+        if is_expected && !duplicates.is_empty() {
             println!("duplicate artfacts found when compiling a tool, this \
                       typically means that something was recompiled because \
                       a transitive dependency has different features activated \
@@ -170,7 +170,7 @@ impl Step for ToolBuild {
                 println!("    `{}` additionally enabled features {:?} at {:?}",
                          prev.0, &prev_features - &cur_features, prev.1);
             }
-            println!("");
+            println!();
             println!("to fix this you will probably want to edit the local \
                       src/tools/rustc-workspace-hack/Cargo.toml crate, as \
                       that will update the dependency graph to ensure that \
@@ -188,7 +188,7 @@ impl Step for ToolBuild {
             if !is_optional_tool {
                 exit(1);
             } else {
-                return None;
+                None
             }
         } else {
             let cargo_out = builder.cargo_out(compiler, self.mode, target)
@@ -251,7 +251,7 @@ pub fn prepare_tool_cargo(
     if let Some(date) = info.commit_date() {
         cargo.env("CFG_COMMIT_DATE", date);
     }
-    if features.len() > 0 {
+    if !features.is_empty() {
         cargo.arg("--features").arg(&features.join(", "));
     }
     cargo

src/ci/run.sh

@@ -40,6 +40,7 @@ RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --enable-sccache"
 RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --disable-manage-submodules"
 RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --enable-locked-deps"
 RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --enable-cargo-native-static"
+RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set rust.codegen-units-std=1"
 
 if [ "$DIST_SRC" = "" ]; then
   RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --disable-dist-src"

src/librustc/infer/combine.rs

@@ -251,6 +251,7 @@ impl<'infcx, 'gcx, 'tcx> CombineFields<'infcx, 'gcx, 'tcx> {
                   dir: RelationDir)
                   -> RelateResult<'tcx, Generalization<'tcx>>
     {
+        debug!("generalize(ty={:?}, for_vid={:?}, dir={:?}", ty, for_vid, dir);
         // Determine the ambient variance within which `ty` appears.
         // The surrounding equation is:
         //
@@ -273,8 +274,15 @@ impl<'infcx, 'gcx, 'tcx> CombineFields<'infcx, 'gcx, 'tcx> {
             root_ty: ty,
         };
 
-        let ty = generalize.relate(&ty, &ty)?;
+        let ty = match generalize.relate(&ty, &ty) {
+            Ok(ty) => ty,
+            Err(e) => {
+                debug!("generalize: failure {:?}", e);
+                return Err(e);
+            }
+        };
         let needs_wf = generalize.needs_wf;
+        debug!("generalize: success {{ {:?}, {:?} }}", ty, needs_wf);
         Ok(Generalization { ty, needs_wf })
     }
 }

src/librustc/infer/equate.rs

@@ -74,6 +74,9 @@ impl<'combine, 'infcx, 'gcx, 'tcx> TypeRelation<'infcx, 'gcx, 'tcx>
         let infcx = self.fields.infcx;
         let a = infcx.type_variables.borrow_mut().replace_if_possible(a);
         let b = infcx.type_variables.borrow_mut().replace_if_possible(b);
+
+        debug!("{}.tys: replacements ({:?}, {:?})", self.tag(), a, b);
+
         match (&a.sty, &b.sty) {
             (&ty::Infer(TyVar(a_id)), &ty::Infer(TyVar(b_id))) => {
                 infcx.type_variables.borrow_mut().equate(a_id, b_id);

src/librustc/infer/outlives/obligations.rs

@@ -458,7 +458,7 @@ where
             );
             debug!("projection_must_outlive: unique declared bound appears in trait ref");
             self.delegate
-                .push_sub_region_constraint(origin.clone(), region, unique_bound);
+                .push_sub_region_constraint(origin, region, unique_bound);
             return;
         }
 

src/librustc/infer/region_constraints/mod.rs

@@ -749,7 +749,7 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
                 a // LUB(a,a) = a
             }
 
-            _ => self.combine_vars(tcx, Lub, a, b, origin.clone()),
+            _ => self.combine_vars(tcx, Lub, a, b, origin),
         }
     }
 
@@ -771,7 +771,7 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
                 a // GLB(a,a) = a
             }
 
-            _ => self.combine_vars(tcx, Glb, a, b, origin.clone()),
+            _ => self.combine_vars(tcx, Glb, a, b, origin),
         }
     }
 

src/librustc/macros.rs

@@ -83,7 +83,14 @@ macro_rules! __impl_stable_hash_field {
 macro_rules! impl_stable_hash_for {
     // FIXME(mark-i-m): Some of these should be `?` rather than `*`. See the git blame and change
     // them back when `?` is supported again.
-    (enum $enum_name:path { $( $variant:ident $( ( $($field:ident $(-> $delegate:tt)*),* ) )* ),* $(,)* }) => {
+    (enum $enum_name:path {
+        $( $variant:ident
+           // this incorrectly allows specifying both tuple-like and struct-like fields, as in `Variant(a,b){c,d}`,
+           // when it should be only one or the other
+           $( ( $($field:ident $(-> $delegate:tt)*),* ) )*
+           $( { $($named_field:ident $(-> $named_delegate:tt)*),* } )*
+        ),* $(,)*
+    }) => {
         impl<'a, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a>> for $enum_name {
             #[inline]
             fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,
@@ -94,8 +101,9 @@ macro_rules! impl_stable_hash_for {
 
                 match *self {
                     $(
-                        $variant $( ( $(ref $field),* ) )* => {
+                        $variant $( ( $(ref $field),* ) )* $( { $(ref $named_field),* } )* => {
                             $($( __impl_stable_hash_field!($field, __ctx, __hasher $(, $delegate)*) );*)*
+                            $($( __impl_stable_hash_field!($named_field, __ctx, __hasher $(, $named_delegate)*) );*)*
                         }
                     )*
                 }
@@ -133,10 +141,11 @@ macro_rules! impl_stable_hash_for {
         }
     };
 
-    (impl<$tcx:lifetime $(, $T:ident)*> for struct $struct_name:path {
-        $($field:ident),* $(,)*
+    (impl<$tcx:lifetime $(, $lt:lifetime $(: $lt_bound:lifetime)*)* $(, $T:ident)*> for struct $struct_name:path {
+        $($field:ident $(-> $delegate:tt)*),* $(,)*
     }) => {
-        impl<'a, $tcx, $($T,)*> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a>> for $struct_name
+        impl<'a, $tcx, $($lt $(: $lt_bound)*,)* $($T,)*>
+            ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a>> for $struct_name
             where $($T: ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a>>),*
         {
             #[inline]
@@ -147,7 +156,7 @@ macro_rules! impl_stable_hash_for {
                     $(ref $field),*
                 } = *self;
 
-                $( $field.hash_stable(__ctx, __hasher));*
+                $( __impl_stable_hash_field!($field, __ctx, __hasher $(, $delegate)*) );*
             }
         }
     };

src/librustc/mir/mod.rs

@@ -1674,6 +1674,10 @@ impl<'tcx> Statement<'tcx> {
     /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
     /// invalidating statement indices in `Location`s.
     pub fn make_nop(&mut self) {
+        // `Statement` contributes significantly to peak memory usage. Make
+        // sure it doesn't get bigger.
+        static_assert!(STATEMENT_IS_AT_MOST_56_BYTES: mem::size_of::<Statement<'_>>() <= 56);
+
         self.kind = StatementKind::Nop
     }
 
@@ -1737,7 +1741,7 @@ pub enum StatementKind<'tcx> {
     /// - `Contravariant` -- requires that `T_y :> T`
     /// - `Invariant` -- requires that `T_y == T`
     /// - `Bivariant` -- no effect
-    AscribeUserType(Place<'tcx>, ty::Variance, UserTypeAnnotation<'tcx>),
+    AscribeUserType(Place<'tcx>, ty::Variance, Box<UserTypeAnnotation<'tcx>>),
 
     /// No-op. Useful for deleting instructions without affecting statement indices.
     Nop,

src/librustc/mir/traversal.rs

@@ -34,6 +34,7 @@ pub struct Preorder<'a, 'tcx: 'a> {
     mir: &'a Mir<'tcx>,
     visited: BitSet<BasicBlock>,
     worklist: Vec<BasicBlock>,
+    root_is_start_block: bool,
 }
 
 impl<'a, 'tcx> Preorder<'a, 'tcx> {
@@ -44,6 +45,7 @@ impl<'a, 'tcx> Preorder<'a, 'tcx> {
             mir,
             visited: BitSet::new_empty(mir.basic_blocks().len()),
             worklist,
+            root_is_start_block: root == START_BLOCK,
         }
     }
 }
@@ -75,15 +77,19 @@ impl<'a, 'tcx> Iterator for Preorder<'a, 'tcx> {
 
     fn size_hint(&self) -> (usize, Option<usize>) {
         // All the blocks, minus the number of blocks we've visited.
-        let remaining = self.mir.basic_blocks().len() - self.visited.count();
+        let upper = self.mir.basic_blocks().len() - self.visited.count();
 
-        // We will visit all remaining blocks exactly once.
-        (remaining, Some(remaining))
+        let lower = if self.root_is_start_block {
+            // We will visit all remaining blocks exactly once.
+            upper
+        } else {
+            self.worklist.len()
+        };
+
+        (lower, Some(upper))
     }
 }
 
-impl<'a, 'tcx> ExactSizeIterator for Preorder<'a, 'tcx> {}
-
 /// Postorder traversal of a graph.
 ///
 /// Postorder traversal is when each node is visited after all of it's
@@ -105,7 +111,8 @@ impl<'a, 'tcx> ExactSizeIterator for Preorder<'a, 'tcx> {}
 pub struct Postorder<'a, 'tcx: 'a> {
     mir: &'a Mir<'tcx>,
     visited: BitSet<BasicBlock>,
-    visit_stack: Vec<(BasicBlock, Successors<'a>)>
+    visit_stack: Vec<(BasicBlock, Successors<'a>)>,
+    root_is_start_block: bool,
 }
 
 impl<'a, 'tcx> Postorder<'a, 'tcx> {
@@ -113,7 +120,8 @@ impl<'a, 'tcx> Postorder<'a, 'tcx> {
         let mut po = Postorder {
             mir,
             visited: BitSet::new_empty(mir.basic_blocks().len()),
-            visit_stack: Vec::new()
+            visit_stack: Vec::new(),
+            root_is_start_block: root == START_BLOCK,
         };
 
 
@@ -214,15 +222,19 @@ impl<'a, 'tcx> Iterator for Postorder<'a, 'tcx> {
 
     fn size_hint(&self) -> (usize, Option<usize>) {
         // All the blocks, minus the number of blocks we've visited.
-        let remaining = self.mir.basic_blocks().len() - self.visited.count();
+        let upper = self.mir.basic_blocks().len() - self.visited.count();
 
-        // We will visit all remaining blocks exactly once.
-        (remaining, Some(remaining))
+        let lower = if self.root_is_start_block {
+            // We will visit all remaining blocks exactly once.
+            upper
+        } else {
+            self.visit_stack.len()
+        };
+
+        (lower, Some(upper))
     }
 }
 
-impl<'a, 'tcx> ExactSizeIterator for Postorder<'a, 'tcx> {}
-
 /// Reverse postorder traversal of a graph
 ///
 /// Reverse postorder is the reverse order of a postorder traversal.

src/librustc/traits/error_reporting.rs

@@ -239,7 +239,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
 
             let msg = format!("type mismatch resolving `{}`", predicate);
             let error_id = (DiagnosticMessageId::ErrorId(271),
-                            Some(obligation.cause.span), msg.clone());
+                            Some(obligation.cause.span), msg);
             let fresh = self.tcx.sess.one_time_diagnostics.borrow_mut().insert(error_id);
             if fresh {
                 let mut diag = struct_span_err!(
@@ -379,7 +379,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             }
         }
         if let Some(t) = self.get_parent_trait_ref(&obligation.cause.code) {
-            flags.push(("parent_trait".to_owned(), Some(t.to_string())));
+            flags.push(("parent_trait".to_owned(), Some(t)));
         }
 
         if let Some(k) = obligation.cause.span.compiler_desugaring_kind() {

src/librustc/traits/project.rs

@@ -594,7 +594,7 @@ fn opt_normalize_projection_type<'a, 'b, 'gcx, 'tcx>(
 
             // But for now, let's classify this as an overflow:
             let recursion_limit = *selcx.tcx().sess.recursion_limit.get();
-            let obligation = Obligation::with_depth(cause.clone(),
+            let obligation = Obligation::with_depth(cause,
                                                     recursion_limit,
                                                     param_env,
                                                     projection_ty);

src/librustc/traits/select.rs

@@ -1522,6 +1522,33 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
             .map(|v| v.get(tcx))
     }
 
+    /// Determines whether can we safely cache the result
+    /// of selecting an obligation. This is almost always 'true',
+    /// except when dealing with certain ParamCandidates.
+    ///
+    /// Ordinarily, a ParamCandidate will contain no inference variables,
+    /// since it was usually produced directly from a DefId. However,
+    /// certain cases (currently only librustdoc's blanket impl finder),
+    /// a ParamEnv may be explicitly constructed with inference types.
+    /// When this is the case, we do *not* want to cache the resulting selection
+    /// candidate. This is due to the fact that it might not always be possible
+    /// to equate the obligation's trait ref and the candidate's trait ref,
+    /// if more constraints end up getting added to an inference variable.
+    ///
+    /// Because of this, we always want to re-run the full selection
+    /// process for our obligation the next time we see it, since
+    /// we might end up picking a different SelectionCandidate (or none at all)
+    fn can_cache_candidate(&self,
+        result: &SelectionResult<'tcx, SelectionCandidate<'tcx>>
+     ) -> bool {
+        match result {
+            Ok(Some(SelectionCandidate::ParamCandidate(trait_ref))) => {
+                !trait_ref.skip_binder().input_types().any(|t| t.walk().any(|t_| t_.is_ty_infer()))
+            },
+            _ => true
+        }
+    }
+
     fn insert_candidate_cache(
         &mut self,
         param_env: ty::ParamEnv<'tcx>,
@@ -1531,6 +1558,14 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
     ) {
         let tcx = self.tcx();
         let trait_ref = cache_fresh_trait_pred.skip_binder().trait_ref;
+
+        if !self.can_cache_candidate(&candidate) {
+            debug!("insert_candidate_cache(trait_ref={:?}, candidate={:?} -\
+                    candidate is not cacheable", trait_ref, candidate);
+            return;
+
+        }
+
         if self.can_use_global_caches(param_env) {
             if let Err(Overflow) = candidate {
                 // Don't cache overflow globally; we only produce this

src/librustc/ty/context.rs

@@ -1200,7 +1200,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             cstore,
             global_arenas: &arenas.global,
             global_interners: interners,
-            dep_graph: dep_graph.clone(),
+            dep_graph,
             types: common_types,
             trait_map,
             export_map: resolutions.export_map.into_iter().map(|(k, v)| {

src/librustc_borrowck/borrowck/mod.rs

@@ -695,7 +695,7 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
                 let mut err = self.cannot_act_on_moved_value(use_span,
                                                              verb,
                                                              msg,
-                                                             Some(nl.to_string()),
+                                                             Some(nl),
                                                              Origin::Ast);
                 let need_note = match lp.ty.sty {
                     ty::Closure(id, _) => {

src/librustc_borrowck/borrowck/move_data.rs

@@ -347,7 +347,7 @@ impl<'a, 'tcx> MoveData<'tcx> {
             lp = base_lp.clone();
         }
 
-        self.add_move_helper(tcx, orig_lp.clone(), id, kind);
+        self.add_move_helper(tcx, orig_lp, id, kind);
     }
 
     fn add_move_helper(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
@@ -359,7 +359,7 @@ impl<'a, 'tcx> MoveData<'tcx> {
                id,
                kind);
 
-        let path_index = self.move_path(tcx, lp.clone());
+        let path_index = self.move_path(tcx, lp);
         let move_index = MoveIndex(self.moves.borrow().len());
 
         let next_move = self.path_first_move(path_index);
@@ -402,7 +402,7 @@ impl<'a, 'tcx> MoveData<'tcx> {
             }
         }
 
-        self.add_assignment_helper(tcx, lp.clone(), assign_id, span);
+        self.add_assignment_helper(tcx, lp, assign_id, span);
     }
 
     fn add_assignment_helper(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>,

src/librustc_codegen_llvm/base.rs

@@ -784,7 +784,7 @@ pub fn codegen_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
        !tcx.sess.opts.output_types.should_codegen() {
         let ongoing_codegen = write::start_async_codegen(
             tcx,
-            time_graph.clone(),
+            time_graph,
             metadata,
             rx,
             1);

src/librustc_codegen_utils/link.rs

@@ -138,7 +138,7 @@ pub fn filename_for_input(sess: &Session,
             let suffix = &sess.target.target.options.exe_suffix;
             let out_filename = outputs.path(OutputType::Exe);
             if suffix.is_empty() {
-                out_filename.to_path_buf()
+                out_filename
             } else {
                 out_filename.with_extension(&suffix[1..])
             }

src/librustc_mir/borrow_check/error_reporting.rs

@@ -1615,7 +1615,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
                 ProjectionElem::Index(..)
                 | ProjectionElem::ConstantIndex { .. }
                 | ProjectionElem::Subslice { .. } => {
-                    self.describe_field(&proj.base, field).to_string()
+                    self.describe_field(&proj.base, field)
                 }
             },
         }

src/librustc_mir/borrow_check/nll/type_check/mod.rs

@@ -1225,7 +1225,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                     );
                 };
             }
-            StatementKind::AscribeUserType(ref place, variance, c_ty) => {
+            StatementKind::AscribeUserType(ref place, variance, box c_ty) => {
                 let place_ty = place.ty(mir, tcx).to_ty(tcx);
                 if let Err(terr) = self.relate_type_and_user_type(
                     place_ty,

src/librustc_mir/build/expr/as_place.rs

@@ -147,7 +147,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                             kind: StatementKind::AscribeUserType(
                                 place.clone(),
                                 Variance::Invariant,
-                                user_ty,
+                                box user_ty,
                             ),
                         },
                     );
@@ -167,7 +167,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                             kind: StatementKind::AscribeUserType(
                                 Place::Local(temp.clone()),
                                 Variance::Invariant,
-                                user_ty,
+                                box user_ty,
                             ),
                         },
                     );

src/librustc_mir/build/matches/mod.rs

@@ -265,7 +265,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     block,
                     Statement {
                         source_info,
-                        kind: StatementKind::FakeRead(FakeReadCause::ForLet, place.clone()),
+                        kind: StatementKind::FakeRead(FakeReadCause::ForLet, place),
                     },
                 );
 
@@ -314,9 +314,9 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     Statement {
                         source_info: ty_source_info,
                         kind: StatementKind::AscribeUserType(
-                            place.clone(),
+                            place,
                             ty::Variance::Invariant,
-                            ascription_user_ty,
+                            box ascription_user_ty,
                         ),
                     },
                 );
@@ -1323,7 +1323,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     kind: StatementKind::AscribeUserType(
                         ascription.source.clone(),
                         ty::Variance::Covariant,
-                        ascription.user_ty,
+                        box ascription.user_ty,
                     ),
                 },
             );

src/librustc_mir/build/matches/test.rs

@@ -324,7 +324,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     let ref_ty = self.hir.tcx().mk_ref(region, tam);
 
                     // let lhs_ref_place = &lhs;
-                    let ref_rvalue = Rvalue::Ref(region, BorrowKind::Shared, place.clone());
+                    let ref_rvalue = Rvalue::Ref(region, BorrowKind::Shared, place);
                     let lhs_ref_place = self.temp(ref_ty, test.span);
                     self.cfg.push_assign(block, source_info, &lhs_ref_place, ref_rvalue);
                     let val = Operand::Move(lhs_ref_place);

src/librustc_mir/build/mod.rs

@@ -644,7 +644,7 @@ fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
         }).collect()
     });
 
-    let mut builder = Builder::new(hir.clone(),
+    let mut builder = Builder::new(hir,
         span,
         arguments.len(),
         safety,
@@ -714,7 +714,7 @@ fn construct_const<'a, 'gcx, 'tcx>(
     let ty = hir.tables().expr_ty_adjusted(ast_expr);
     let owner_id = tcx.hir.body_owner(body_id);
     let span = tcx.hir.span(owner_id);
-    let mut builder = Builder::new(hir.clone(), span, 0, Safety::Safe, ty, ty_span,vec![]);
+    let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty, ty_span,vec![]);
 
     let mut block = START_BLOCK;
     let expr = builder.hir.mirror(ast_expr);

src/librustc_mir/hair/pattern/_match.rs

@@ -931,12 +931,37 @@ impl<'tcx> IntRange<'tcx> {
     }
 }
 
-// Return a set of constructors equivalent to `all_ctors \ used_ctors`.
+// A request for missing constructor data in terms of either:
+// - whether or not there any missing constructors; or
+// - the actual set of missing constructors.
+#[derive(PartialEq)]
+enum MissingCtorsInfo {
+    Emptiness,
+    Ctors,
+}
+
+// Used by `compute_missing_ctors`.
+#[derive(Debug, PartialEq)]
+enum MissingCtors<'tcx> {
+    Empty,
+    NonEmpty,
+
+    // Note that the Vec can be empty.
+    Ctors(Vec<Constructor<'tcx>>),
+}
+
+// When `info` is `MissingCtorsInfo::Ctors`, compute a set of constructors
+// equivalent to `all_ctors \ used_ctors`. When `info` is
+// `MissingCtorsInfo::Emptiness`, just determines if that set is empty or not.
+// (The split logic gives a performance win, because we always need to know if
+// the set is empty, but we rarely need the full set, and it can be expensive
+// to compute the full set.)
 fn compute_missing_ctors<'a, 'tcx: 'a>(
+    info: MissingCtorsInfo,
     tcx: TyCtxt<'a, 'tcx, 'tcx>,
     all_ctors: &Vec<Constructor<'tcx>>,
     used_ctors: &Vec<Constructor<'tcx>>,
-) -> Vec<Constructor<'tcx>> {
+) -> MissingCtors<'tcx> {
     let mut missing_ctors = vec![];
 
     for req_ctor in all_ctors {
@@ -965,10 +990,22 @@ fn compute_missing_ctors<'a, 'tcx: 'a>(
         // We add `refined_ctors` instead of `req_ctor`, because then we can
         // provide more detailed error information about precisely which
         // ranges have been omitted.
-        missing_ctors.extend(refined_ctors);
+        if info == MissingCtorsInfo::Emptiness {
+            if !refined_ctors.is_empty() {
+                // The set is non-empty; return early.
+                return MissingCtors::NonEmpty;
+            }
+        } else {
+            missing_ctors.extend(refined_ctors);
+        }
     }
 
-    missing_ctors
+    if info == MissingCtorsInfo::Emptiness {
+        // If we reached here, the set is empty.
+        MissingCtors::Empty
+    } else {
+        MissingCtors::Ctors(missing_ctors)
+    }
 }
 
 /// Algorithm from http://moscova.inria.fr/~maranget/papers/warn/index.html
@@ -1081,20 +1118,23 @@ pub fn is_useful<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
         // feature flag is not present, so this is only
         // needed for that case.
 
-        // Find those constructors that are not matched by any non-wildcard patterns in the
-        // current column.
-        let missing_ctors = compute_missing_ctors(cx.tcx, &all_ctors, &used_ctors);
+        // Missing constructors are those that are not matched by any
+        // non-wildcard patterns in the current column. We always determine if
+        // the set is empty, but we only fully construct them on-demand,
+        // because they're rarely used and can be big.
+        let cheap_missing_ctors =
+            compute_missing_ctors(MissingCtorsInfo::Emptiness, cx.tcx, &all_ctors, &used_ctors);
 
         let is_privately_empty = all_ctors.is_empty() && !cx.is_uninhabited(pcx.ty);
         let is_declared_nonexhaustive = cx.is_non_exhaustive_enum(pcx.ty) && !cx.is_local(pcx.ty);
-        debug!("missing_ctors={:#?} is_privately_empty={:#?} is_declared_nonexhaustive={:#?}",
-               missing_ctors, is_privately_empty, is_declared_nonexhaustive);
+        debug!("cheap_missing_ctors={:#?} is_privately_empty={:#?} is_declared_nonexhaustive={:#?}",
+               cheap_missing_ctors, is_privately_empty, is_declared_nonexhaustive);
 
         // For privately empty and non-exhaustive enums, we work as if there were an "extra"
         // `_` constructor for the type, so we can never match over all constructors.
         let is_non_exhaustive = is_privately_empty || is_declared_nonexhaustive;
 
-        if missing_ctors.is_empty() && !is_non_exhaustive {
+        if cheap_missing_ctors == MissingCtors::Empty && !is_non_exhaustive {
             split_grouped_constructors(cx.tcx, all_ctors, matrix, pcx.ty).into_iter().map(|c| {
                 is_useful_specialized(cx, matrix, v, c, pcx.ty, witness)
             }).find(|result| result.is_useful()).unwrap_or(NotUseful)
@@ -1165,15 +1205,22 @@ pub fn is_useful<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
                             witness
                         }).collect()
                     } else {
-                        pats.into_iter().flat_map(|witness| {
-                            missing_ctors.iter().map(move |ctor| {
-                                // Extends the witness with a "wild" version of this
-                                // constructor, that matches everything that can be built with
-                                // it. For example, if `ctor` is a `Constructor::Variant` for
-                                // `Option::Some`, this pushes the witness for `Some(_)`.
-                                witness.clone().push_wild_constructor(cx, ctor, pcx.ty)
-                            })
-                        }).collect()
+                        let expensive_missing_ctors =
+                            compute_missing_ctors(MissingCtorsInfo::Ctors, cx.tcx, &all_ctors,
+                                                  &used_ctors);
+                        if let MissingCtors::Ctors(missing_ctors) = expensive_missing_ctors {
+                            pats.into_iter().flat_map(|witness| {
+                                missing_ctors.iter().map(move |ctor| {
+                                    // Extends the witness with a "wild" version of this
+                                    // constructor, that matches everything that can be built with
+                                    // it. For example, if `ctor` is a `Constructor::Variant` for
+                                    // `Option::Some`, this pushes the witness for `Some(_)`.
+                                    witness.clone().push_wild_constructor(cx, ctor, pcx.ty)
+                                })
+                            }).collect()
+                        } else {
+                            bug!("cheap missing ctors")
+                        }
                     };
                     UsefulWithWitness(new_witnesses)
                 }

src/librustc_mir/interpret/snapshot.rs

@@ -6,9 +6,8 @@
 // it is not used by the general miri engine, just by CTFE.
 
 use std::hash::{Hash, Hasher};
-use std::mem;
 
-use rustc::ich::{StableHashingContext, StableHashingContextProvider};
+use rustc::ich::StableHashingContextProvider;
 use rustc::mir;
 use rustc::mir::interpret::{
     AllocId, Pointer, Scalar,
@@ -20,7 +19,7 @@ use rustc::ty::{self, TyCtxt};
 use rustc::ty::layout::Align;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::indexed_vec::IndexVec;
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableHasherResult};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use syntax::ast::Mutability;
 use syntax::source_map::Span;
 
@@ -217,23 +216,10 @@ impl_snapshot_for!(struct MemPlace {
     align -> *align, // just copy alignment verbatim
 });
 
-// Can't use the macro here because that does not support named enum fields.
-impl<'a> HashStable<StableHashingContext<'a>> for Place {
-    fn hash_stable<W: StableHasherResult>(
-        &self, hcx: &mut StableHashingContext<'a>,
-        hasher: &mut StableHasher<W>)
-    {
-        mem::discriminant(self).hash_stable(hcx, hasher);
-        match self {
-            Place::Ptr(mem_place) => mem_place.hash_stable(hcx, hasher),
-
-            Place::Local { frame, local } => {
-                frame.hash_stable(hcx, hasher);
-                local.hash_stable(hcx, hasher);
-            },
-        }
-    }
-}
+impl_stable_hash_for!(enum ::interpret::Place {
+    Ptr(mem_place),
+    Local { frame, local },
+});
 impl<'a, Ctx> Snapshot<'a, Ctx> for Place
     where Ctx: SnapshotContext<'a>,
 {
@@ -317,20 +303,10 @@ impl<'a, Ctx> Snapshot<'a, Ctx> for &'a Allocation
     }
 }
 
-// Can't use the macro here because that does not support named enum fields.
-impl<'a> HashStable<StableHashingContext<'a>> for StackPopCleanup {
-    fn hash_stable<W: StableHasherResult>(
-        &self,
-        hcx: &mut StableHashingContext<'a>,
-        hasher: &mut StableHasher<W>)
-    {
-        mem::discriminant(self).hash_stable(hcx, hasher);
-        match self {
-            StackPopCleanup::Goto(ref block) => block.hash_stable(hcx, hasher),
-            StackPopCleanup::None { cleanup } => cleanup.hash_stable(hcx, hasher),
-        }
-    }
-}
+impl_stable_hash_for!(enum ::interpret::eval_context::StackPopCleanup {
+    Goto(block),
+    None { cleanup },
+});
 
 #[derive(Eq, PartialEq)]
 struct FrameSnapshot<'a, 'tcx: 'a> {
@@ -343,28 +319,17 @@ struct FrameSnapshot<'a, 'tcx: 'a> {
     stmt: usize,
 }
 
-// Not using the macro because that does not support types depending on two lifetimes
-impl<'a, 'mir, 'tcx: 'mir> HashStable<StableHashingContext<'a>> for Frame<'mir, 'tcx> {
-    fn hash_stable<W: StableHasherResult>(
-        &self,
-        hcx: &mut StableHashingContext<'a>,
-        hasher: &mut StableHasher<W>) {
+impl_stable_hash_for!(impl<'tcx, 'mir: 'tcx> for struct Frame<'mir, 'tcx> {
+    mir,
+    instance,
+    span,
+    return_to_block,
+    return_place -> (return_place.as_ref().map(|r| &**r)),
+    locals,
+    block,
+    stmt,
+});
 
-        let Frame {
-            mir,
-            instance,
-            span,
-            return_to_block,
-            return_place,
-            locals,
-            block,
-            stmt,
-        } = self;
-
-        (mir, instance, span, return_to_block).hash_stable(hcx, hasher);
-        (return_place.as_ref().map(|r| &**r), locals, block, stmt).hash_stable(hcx, hasher);
-    }
-}
 impl<'a, 'mir, 'tcx, Ctx> Snapshot<'a, Ctx> for &'a Frame<'mir, 'tcx>
     where Ctx: SnapshotContext<'a>,
 {
@@ -443,21 +408,11 @@ impl<'a, 'mir, 'tcx> Hash for EvalSnapshot<'a, 'mir, 'tcx>
     }
 }
 
-// Not using the macro because we need special handling for `memory`, which the macro
-// does not support at the same time as the extra bounds on the type.
-impl<'a, 'b, 'mir, 'tcx> HashStable<StableHashingContext<'b>>
-    for EvalSnapshot<'a, 'mir, 'tcx>
-{
-    fn hash_stable<W: StableHasherResult>(
-        &self,
-        hcx: &mut StableHashingContext<'b>,
-        hasher: &mut StableHasher<W>)
-    {
-        // Not hashing memory: Avoid hashing memory all the time during execution
-        let EvalSnapshot{ memory: _, stack } = self;
-        stack.hash_stable(hcx, hasher);
-    }
-}
+impl_stable_hash_for!(impl<'tcx, 'b, 'mir> for struct EvalSnapshot<'b, 'mir, 'tcx> {
+    // Not hashing memory: Avoid hashing memory all the time during execution
+    memory -> _,
+    stack,
+});
 
 impl<'a, 'mir, 'tcx> Eq for EvalSnapshot<'a, 'mir, 'tcx>
 {}

src/librustc_mir/interpret/validity.rs

@@ -463,7 +463,11 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
         // Validate all fields of compound data structures
         let path_len = path.len(); // Remember the length, in case we need to truncate
         match dest.layout.fields {
-            layout::FieldPlacement::Union(..) => {
+            layout::FieldPlacement::Union(fields) => {
+                // Empty unions are not accepted by rustc. That's great, it means we can
+                // use that as an unambiguous signal for detecting primitives.  Make sure
+                // we did not miss any primitive.
+                debug_assert!(fields > 0);
                 // We can't check unions, their bits are allowed to be anything.
                 // The fields don't need to correspond to any bit pattern of the union's fields.
                 // See https://github.com/rust-lang/rust/issues/32836#issuecomment-406875389

src/librustc_mir/shim.rs

@@ -547,7 +547,7 @@ impl<'a, 'tcx> CloneShimBuilder<'a, 'tcx> {
         // `dest[i] = Clone::clone(src[beg])`;
         // Goto #3 if ok, #5 if unwinding happens.
         let dest_field = dest.clone().index(beg);
-        let src_field = src.clone().index(beg);
+        let src_field = src.index(beg);
         self.make_clone_call(dest_field, src_field, ty, BasicBlock::new(3),
                              BasicBlock::new(5));
 

src/librustc_mir/transform/promote_consts.rs

@@ -333,6 +333,14 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
                             let operand = Operand::Copy(promoted_place(ty, span));
                             mem::replace(&mut args[index], operand)
                         }
+                        // We expected a `TerminatorKind::Call` for which we'd like to promote an
+                        // argument. `qualify_consts` saw a `TerminatorKind::Call` here, but
+                        // we are seeing a `Goto`. That means that the `promote_temps` method
+                        // already promoted this call away entirely. This case occurs when calling
+                        // a function requiring a constant argument and as that constant value
+                        // providing a value whose computation contains another call to a function
+                        // requiring a constant argument.
+                        TerminatorKind::Goto { .. } => return,
                         _ => bug!()
                     }
                 }

src/librustc_mir/transform/qualify_consts.rs

@@ -820,7 +820,9 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
 
             let fn_ty = func.ty(self.mir, self.tcx);
             let mut callee_def_id = None;
-            let (mut is_shuffle, mut is_const_fn) = (false, false);
+            let mut is_shuffle = false;
+            let mut is_const_fn = false;
+            let mut is_promotable_const_fn = false;
             if let ty::FnDef(def_id, _) = fn_ty.sty {
                 callee_def_id = Some(def_id);
                 match self.tcx.fn_sig(def_id).abi() {
@@ -881,6 +883,9 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
                             // functions without #[rustc_promotable]
                             if self.tcx.is_promotable_const_fn(def_id) {
                                 is_const_fn = true;
+                                is_promotable_const_fn = true;
+                            } else if self.tcx.is_const_fn(def_id) {
+                                is_const_fn = true;
                             }
                         } else {
                             // stable const fn or unstable const fns with their feature gate
@@ -982,7 +987,17 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
                     if !constant_arguments.contains(&i) {
                         return
                     }
-                    if this.qualif.is_empty() {
+                    // Since the argument is required to be constant,
+                    // we care about constness, not promotability.
+                    // If we checked for promotability, we'd miss out on
+                    // the results of function calls (which are never promoted
+                    // in runtime code)
+                    // This is not a problem, because the argument explicitly
+                    // requests constness, in contrast to regular promotion
+                    // which happens even without the user requesting it.
+                    // We can error out with a hard error if the argument is not
+                    // constant here.
+                    if (this.qualif - Qualif::NOT_PROMOTABLE).is_empty() {
                         this.promotion_candidates.push(candidate);
                     } else {
                         this.tcx.sess.span_err(this.span,
@@ -1011,7 +1026,11 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
                     // Be conservative about the returned value of a const fn.
                     let tcx = self.tcx;
                     let ty = dest.ty(self.mir, tcx).to_ty(tcx);
-                    self.qualif = Qualif::empty();
+                    if is_const_fn && !is_promotable_const_fn && self.mode == Mode::Fn {
+                        self.qualif = Qualif::NOT_PROMOTABLE;
+                    } else {
+                        self.qualif = Qualif::empty();
+                    }
                     self.add_type(ty);
                 }
                 self.assign(dest, location);

src/librustc_mir/util/elaborate_drops.rs

@@ -753,11 +753,11 @@ impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
                 self.place.clone()
             )));
             drop_block_stmts.push(self.assign(&cur, Rvalue::Cast(
-                CastKind::Misc, Operand::Move(tmp.clone()), iter_ty
+                CastKind::Misc, Operand::Move(tmp), iter_ty
             )));
             drop_block_stmts.push(self.assign(&length_or_end,
                 Rvalue::BinaryOp(BinOp::Offset,
-                     Operand::Copy(cur.clone()), Operand::Move(length.clone())
+                     Operand::Copy(cur), Operand::Move(length)
             )));
         } else {
             // index = 0 (length already pushed)

src/librustc_resolve/build_reduced_graph.rs

@@ -218,7 +218,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                 };
                 this.add_import_directive(
                     base.into_iter().collect(),
-                    subclass.clone(),
+                    subclass,
                     source.ident.span,
                     id,
                     root_use_tree.span,

src/librustc_save_analysis/dump_visitor.rs

@@ -105,7 +105,7 @@ impl<'l, 'tcx: 'l, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
             tcx: save_ctxt.tcx,
             save_ctxt,
             dumper,
-            span: span_utils.clone(),
+            span: span_utils,
             cur_scope: CRATE_NODE_ID,
             // mac_defs: FxHashSet::default(),
             macro_calls: FxHashSet::default(),

src/librustc_target/spec/mod.rs

@@ -1132,7 +1132,7 @@ impl ToJson for Target {
         macro_rules! target_val {
             ($attr:ident) => ( {
                 let name = (stringify!($attr)).replace("_", "-");
-                d.insert(name.to_string(), self.$attr.to_json());
+                d.insert(name, self.$attr.to_json());
             } );
             ($attr:ident, $key_name:expr) => ( {
                 let name = $key_name;
@@ -1144,7 +1144,7 @@ impl ToJson for Target {
             ($attr:ident) => ( {
                 let name = (stringify!($attr)).replace("_", "-");
                 if default.$attr != self.options.$attr {
-                    d.insert(name.to_string(), self.options.$attr.to_json());
+                    d.insert(name, self.options.$attr.to_json());
                 }
             } );
             ($attr:ident, $key_name:expr) => ( {
@@ -1160,7 +1160,7 @@ impl ToJson for Target {
                         .iter()
                         .map(|(k, v)| (k.desc().to_owned(), v.clone()))
                         .collect::<BTreeMap<_, _>>();
-                    d.insert(name.to_string(), obj.to_json());
+                    d.insert(name, obj.to_json());
                 }
             } );
             (env - $attr:ident) => ( {
@@ -1170,7 +1170,7 @@ impl ToJson for Target {
                         .iter()
                         .map(|&(ref k, ref v)| k.clone() + "=" + &v)
                         .collect::<Vec<_>>();
-                    d.insert(name.to_string(), obj.to_json());
+                    d.insert(name, obj.to_json());
                 }
             } );
 

src/librustc_typeck/check/autoderef.rs

@@ -61,7 +61,7 @@ impl<'a, 'gcx, 'tcx> Iterator for Autoderef<'a, 'gcx, 'tcx> {
             let suggested_limit = *tcx.sess.recursion_limit.get() * 2;
             let msg = format!("reached the recursion limit while auto-dereferencing {:?}",
                               self.cur_ty);
-            let error_id = (DiagnosticMessageId::ErrorId(55), Some(self.span), msg.clone());
+            let error_id = (DiagnosticMessageId::ErrorId(55), Some(self.span), msg);
             let fresh = tcx.sess.one_time_diagnostics.borrow_mut().insert(error_id);
             if fresh {
                 struct_span_err!(tcx.sess,

src/librustc_typeck/check/coercion.rs

@@ -61,7 +61,7 @@
 //! we may want to adjust precisely when coercions occur.
 
 use check::{FnCtxt, Needs};
-
+use errors::DiagnosticBuilder;
 use rustc::hir;
 use rustc::hir::def_id::DefId;
 use rustc::infer::{Coercion, InferResult, InferOk};
@@ -72,14 +72,12 @@ use rustc::ty::{self, TypeAndMut, Ty, ClosureSubsts};
 use rustc::ty::fold::TypeFoldable;
 use rustc::ty::error::TypeError;
 use rustc::ty::relate::RelateResult;
-use errors::DiagnosticBuilder;
+use smallvec::{smallvec, SmallVec};
+use std::ops::Deref;
 use syntax::feature_gate;
 use syntax::ptr::P;
 use syntax_pos;
 
-use std::collections::VecDeque;
-use std::ops::Deref;
-
 struct Coerce<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
     fcx: &'a FnCtxt<'a, 'gcx, 'tcx>,
     cause: ObligationCause<'tcx>,
@@ -536,18 +534,23 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> {
 
         let mut selcx = traits::SelectionContext::new(self);
 
-        // Use a FIFO queue for this custom fulfillment procedure. (The maximum
-        // length is almost always 1.)
-        let mut queue = VecDeque::with_capacity(1);
-
         // Create an obligation for `Source: CoerceUnsized<Target>`.
         let cause = ObligationCause::misc(self.cause.span, self.body_id);
-        queue.push_back(self.tcx.predicate_for_trait_def(self.fcx.param_env,
-                                                         cause,
-                                                         coerce_unsized_did,
-                                                         0,
-                                                         coerce_source,
-                                                         &[coerce_target.into()]));
+
+        // Use a FIFO queue for this custom fulfillment procedure.
+        //
+        // A Vec (or SmallVec) is not a natural choice for a queue. However,
+        // this code path is hot, and this queue usually has a max length of 1
+        // and almost never more than 3. By using a SmallVec we avoid an
+        // allocation, at the (very small) cost of (occasionally) having to
+        // shift subsequent elements down when removing the front element.
+        let mut queue: SmallVec<[_; 4]> =
+            smallvec![self.tcx.predicate_for_trait_def(self.fcx.param_env,
+                                                       cause,
+                                                       coerce_unsized_did,
+                                                       0,
+                                                       coerce_source,
+                                                       &[coerce_target.into()])];
 
         let mut has_unsized_tuple_coercion = false;
 
@@ -555,7 +558,8 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> {
         // emitting a coercion in cases like `Foo<$1>` -> `Foo<$2>`, where
         // inference might unify those two inner type variables later.
         let traits = [coerce_unsized_did, unsize_did];
-        while let Some(obligation) = queue.pop_front() {
+        while !queue.is_empty() {
+            let obligation = queue.remove(0);
             debug!("coerce_unsized resolve step: {:?}", obligation);
             let trait_ref = match obligation.predicate {
                 ty::Predicate::Trait(ref tr) if traits.contains(&tr.def_id()) => {

src/librustc_typeck/check/compare_method.rs

@@ -325,7 +325,7 @@ fn compare_predicate_entailment<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                         diag.span_suggestion_with_applicability(
                             impl_err_span,
                             "consider change the type to match the mutability in trait",
-                            trait_err_str.to_string(),
+                            trait_err_str,
                             Applicability::MachineApplicable,
                         );
                     }

src/librustc_typeck/check/method/probe.rs

@@ -1157,7 +1157,7 @@ impl<'a, 'gcx, 'tcx> ProbeContext<'a, 'gcx, 'tcx> {
 
                     // Convert the bounds into obligations.
                     let impl_obligations = traits::predicates_for_generics(
-                        cause.clone(), self.param_env, &impl_bounds);
+                        cause, self.param_env, &impl_bounds);
 
                     debug!("impl_obligations={:?}", impl_obligations);
                     impl_obligations.into_iter()
@@ -1175,7 +1175,7 @@ impl<'a, 'gcx, 'tcx> ProbeContext<'a, 'gcx, 'tcx> {
                 TraitCandidate(trait_ref) => {
                     let predicate = trait_ref.to_predicate();
                     let obligation =
-                        traits::Obligation::new(cause.clone(), self.param_env, predicate);
+                        traits::Obligation::new(cause, self.param_env, predicate);
                     if !self.predicate_may_hold(&obligation) {
                         if self.probe(|_| self.select_trait_candidate(trait_ref).is_err()) {
                             // This candidate's primary obligation doesn't even

src/librustc_typeck/check/mod.rs

@@ -4745,25 +4745,17 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         } else if !self.check_for_cast(err, expr, found, expected) {
             let methods = self.get_conversion_methods(expr.span, expected, found);
             if let Ok(expr_text) = self.sess().source_map().span_to_snippet(expr.span) {
-                let suggestions = iter::repeat(expr_text).zip(methods.iter())
+                let suggestions = iter::repeat(&expr_text).zip(methods.iter())
                     .filter_map(|(receiver, method)| {
                         let method_call = format!(".{}()", method.ident);
                         if receiver.ends_with(&method_call) {
                             None  // do not suggest code that is already there (#53348)
                         } else {
-                            /*
-                            methods defined in `method_call_list` will overwrite
-                            `.clone()` in copy of `receiver`
-                            */
                             let method_call_list = [".to_vec()", ".to_string()"];
                             if receiver.ends_with(".clone()")
-                                    && method_call_list.contains(&method_call.as_str()){
-                                // created copy of `receiver` because we don't want other
-                                // suggestion to get affected
-                                let mut new_receiver = receiver.clone();
-                                let max_len = new_receiver.rfind(".").unwrap();
-                                new_receiver.truncate(max_len);
-                                Some(format!("{}{}", new_receiver, method_call))
+                                    && method_call_list.contains(&method_call.as_str()) {
+                                let max_len = receiver.rfind(".").unwrap();
+                                Some(format!("{}{}", &receiver[..max_len], method_call))
                             }
                             else {
                                 Some(format!("{}{}", receiver, method_call))

src/librustdoc/clean/auto_trait.rs

@@ -84,7 +84,7 @@ impl<'a, 'tcx, 'rcx, 'cstore> AutoTraitFinder<'a, 'tcx, 'rcx, 'cstore> {
             .into_iter()
             .chain(self.get_auto_trait_impl_for(
                 def_id,
-                name.clone(),
+                name,
                 generics.clone(),
                 def_ctor,
                 tcx.require_lang_item(lang_items::SyncTraitLangItem),

src/librustdoc/clean/blanket_impl.rs

@@ -50,6 +50,7 @@ impl<'a, 'tcx, 'rcx, 'cstore> BlanketImplFinder <'a, 'tcx, 'rcx, 'cstore> {
         name: Option<String>,
     ) -> Vec<Item>
     where F: Fn(DefId) -> Def {
+        debug!("get_blanket_impls(def_id={:?}, ...)", def_id);
         let mut impls = Vec::new();
         if self.cx
             .tcx
@@ -66,7 +67,7 @@ impl<'a, 'tcx, 'rcx, 'cstore> BlanketImplFinder <'a, 'tcx, 'rcx, 'cstore> {
         }
         let ty = self.cx.tcx.type_of(def_id);
         let generics = self.cx.tcx.generics_of(def_id);
-        let real_name = name.clone().map(|name| Ident::from_str(&name));
+        let real_name = name.map(|name| Ident::from_str(&name));
         let param_env = self.cx.tcx.param_env(def_id);
         for &trait_def_id in self.cx.all_traits.iter() {
             if !self.cx.renderinfo.borrow().access_levels.is_doc_reachable(trait_def_id) ||
@@ -78,6 +79,8 @@ impl<'a, 'tcx, 'rcx, 'cstore> BlanketImplFinder <'a, 'tcx, 'rcx, 'cstore> {
             }
             self.cx.tcx.for_each_relevant_impl(trait_def_id, ty, |impl_def_id| {
                 self.cx.tcx.infer_ctxt().enter(|infcx| {
+                    debug!("get_blanet_impls: Considering impl for trait '{:?}' {:?}",
+                           trait_def_id, impl_def_id);
                     let t_generics = infcx.tcx.generics_of(impl_def_id);
                     let trait_ref = infcx.tcx.impl_trait_ref(impl_def_id)
                                              .expect("Cannot get impl trait");
@@ -104,12 +107,12 @@ impl<'a, 'tcx, 'rcx, 'cstore> BlanketImplFinder <'a, 'tcx, 'rcx, 'cstore> {
                         drop(obligations);
 
                         debug!(
-                            "invoking predicate_may_hold: {:?}",
-                            trait_ref,
+                            "invoking predicate_may_hold: param_env={:?}, trait_ref={:?}, ty={:?}",
+                             param_env, trait_ref, ty
                         );
                         let may_apply = match infcx.evaluate_obligation(
                             &traits::Obligation::new(
-                                cause.clone(),
+                                cause,
                                 param_env,
                                 trait_ref.to_predicate(),
                             ),
@@ -117,6 +120,10 @@ impl<'a, 'tcx, 'rcx, 'cstore> BlanketImplFinder <'a, 'tcx, 'rcx, 'cstore> {
                             Ok(eval_result) => eval_result.may_apply(),
                             Err(traits::OverflowError) => true, // overflow doesn't mean yes *or* no
                         };
+                        debug!("get_blanket_impls: found applicable impl: {}\
+                               for trait_ref={:?}, ty={:?}",
+                               may_apply, trait_ref, ty);
+
                         if !may_apply {
                             return
                         }

src/librustdoc/clean/mod.rs

@@ -3611,7 +3611,7 @@ impl ToSource for syntax_pos::Span {
     fn to_src(&self, cx: &DocContext) -> String {
         debug!("converting span {:?} to snippet", self.clean(cx));
         let sn = match cx.sess().source_map().span_to_snippet(*self) {
-            Ok(x) => x.to_string(),
+            Ok(x) => x,
             Err(_) => String::new()
         };
         debug!("got snippet {}", sn);

src/librustdoc/html/highlight.rs

@@ -28,9 +28,12 @@ use syntax::parse;
 use syntax_pos::{Span, FileName};
 
 /// Highlights `src`, returning the HTML output.
-pub fn render_with_highlighting(src: &str, class: Option<&str>,
-                                extension: Option<&str>,
-                                tooltip: Option<(&str, &str)>) -> String {
+pub fn render_with_highlighting(
+    src: &str,
+    class: Option<&str>,
+    extension: Option<&str>,
+    tooltip: Option<(&str, &str)>,
+) -> String {
     debug!("highlighting: ================\n{}\n==============", src);
     let sess = parse::ParseSess::new(FilePathMapping::empty());
     let fm = sess.source_map().new_source_file(FileName::Custom("stdin".to_string()),
@@ -384,9 +387,9 @@ impl Class {
 }
 
 fn write_header(class: Option<&str>, out: &mut dyn Write) -> io::Result<()> {
-    write!(out, "<pre class=\"rust {}\">\n", class.unwrap_or(""))
+    write!(out, "<div class=\"example-wrap\"><pre class=\"rust {}\">\n", class.unwrap_or(""))
 }
 
 fn write_footer(out: &mut dyn Write) -> io::Result<()> {
-    write!(out, "</pre>\n")
+    write!(out, "</pre></div>\n")
 }

src/librustdoc/html/render.rs

@@ -521,7 +521,7 @@ pub fn run(mut krate: clean::Crate,
             external_html: external_html.clone(),
             krate: krate.name.clone(),
         },
-        css_file_extension: css_file_extension.clone(),
+        css_file_extension,
         created_dirs: Default::default(),
         sort_modules_alphabetically,
         themes,
@@ -1343,7 +1343,7 @@ impl DocFolder for Cache {
                         self.search_index.push(IndexItem {
                             ty: item.type_(),
                             name: s.to_string(),
-                            path: path.join("::").to_string(),
+                            path: path.join("::"),
                             desc: plain_summary_line(item.doc_value()),
                             parent,
                             parent_idx: None,
@@ -1709,6 +1709,7 @@ impl<'a> Settings<'a> {
                 ("method-docs", "Auto-hide item methods' documentation", false),
                 ("go-to-only-result", "Directly go to item in search if there is only one result",
                  false),
+                ("line-numbers", "Show line numbers on code examples", false),
             ],
             root_path,
             suffix,
@@ -2283,7 +2284,7 @@ fn document_short(w: &mut fmt::Formatter, cx: &Context, item: &clean::Item, link
             format!("{} [Read more]({})",
                     &plain_summary_line(Some(s)), naive_assoc_href(item, link))
         } else {
-            plain_summary_line(Some(s)).to_string()
+            plain_summary_line(Some(s))
         };
         render_markdown(w, cx, &markdown, item.links(), prefix)?;
     } else if !prefix.is_empty() {
@@ -2435,7 +2436,7 @@ fn item_module(w: &mut fmt::Formatter, cx: &Context,
     // (which is the position in the vector).
     indices.dedup_by_key(|i| (items[*i].def_id,
                               if items[*i].name.as_ref().is_some() {
-                                  Some(full_path(cx, &items[*i]).clone())
+                                  Some(full_path(cx, &items[*i]))
                               } else {
                                   None
                               },

src/librustdoc/html/static/main.js

@@ -2093,6 +2093,7 @@
         return wrapper;
     }
 
+    var hideItemDeclarations = getCurrentValue('rustdoc-item-declarations') === "false";
     onEach(document.getElementsByClassName('docblock'), function(e) {
         if (hasClass(e, 'autohide')) {
             var wrap = e.previousElementSibling;
@@ -2116,16 +2117,14 @@
             }
         }
         if (e.parentNode.id === "main") {
-            var otherMessage;
+            var otherMessage = '';
             var fontSize;
             var extraClass;
-            var show = true;
 
             if (hasClass(e, "type-decl")) {
                 fontSize = "20px";
                 otherMessage = ' Show declaration';
-                show = getCurrentValue('rustdoc-item-declarations') === "false";
-                if (!show) {
+                if (hideItemDeclarations === false) {
                     extraClass = 'collapsed';
                 }
             } else if (hasClass(e, "non-exhaustive")) {
@@ -2142,8 +2141,12 @@
                 extraClass = "marg-left";
             }
 
-            e.parentNode.insertBefore(createToggle(otherMessage, fontSize, extraClass, show), e);
-            if (otherMessage && show) {
+            e.parentNode.insertBefore(createToggle(otherMessage,
+                                                   fontSize,
+                                                   extraClass,
+                                                   hideItemDeclarations),
+                                      e);
+            if (otherMessage.length > 0 && hideItemDeclarations === true) {
                 collapseDocs(e.previousSibling.childNodes[0], "toggle");
             }
         }
@@ -2186,13 +2189,33 @@
         });
     }
 
+    // To avoid checking on "rustdoc-item-attributes" value on every loop...
+    var itemAttributesFunc = function() {};
+    if (getCurrentValue("rustdoc-item-attributes") !== "false") {
+        itemAttributesFunc = function(x) {
+            collapseDocs(x.previousSibling.childNodes[0], "toggle");
+        };
+    }
     onEach(document.getElementById('main').getElementsByClassName('attributes'), function(i_e) {
         i_e.parentNode.insertBefore(createToggleWrapper(toggle.cloneNode(true)), i_e);
-        if (getCurrentValue("rustdoc-item-attributes") !== "false") {
-            collapseDocs(i_e.previousSibling.childNodes[0], "toggle");
-        }
+        itemAttributesFunc(i_e);
     });
 
+    // To avoid checking on "rustdoc-line-numbers" value on every loop...
+    var lineNumbersFunc = function() {};
+    if (getCurrentValue("rustdoc-line-numbers") === "true") {
+        lineNumbersFunc = function(x) {
+            var count = x.textContent.split('\n').length;
+            var elems = [];
+            for (var i = 0; i < count; ++i) {
+                elems.push(i + 1);
+            }
+            var node = document.createElement('pre');
+            addClass(node, 'line-number');
+            node.innerHTML = elems.join('\n');
+            x.parentNode.insertBefore(node, x);
+        };
+    }
     onEach(document.getElementsByClassName('rust-example-rendered'), function(e) {
         if (hasClass(e, 'compile_fail')) {
             e.addEventListener("mouseover", function(event) {
@@ -2209,6 +2232,7 @@
                 e.previousElementSibling.childNodes[0].style.color = '';
             });
         }
+        lineNumbersFunc(e);
     });
 
     function showModal(content) {

src/librustdoc/html/static/rustdoc.css

@@ -282,6 +282,24 @@ nav.sub {
 	padding-left: 0;
 }
 
+.example-wrap {
+	display: inline-flex;
+	width: 100%;
+}
+
+.example-wrap > pre.line-number {
+	overflow: initial;
+	border: 1px solid;
+	border-top-left-radius: 5px;
+	border-bottom-left-radius: 5px;
+	padding: 13px 8px;
+	text-align: right;
+}
+
+.example-wrap > pre.rust {
+	width: 100%;
+}
+
 #search {
 	margin-left: 230px;
 	position: relative;

src/librustdoc/html/static/themes/dark.css

@@ -233,6 +233,10 @@ pre.rust .question-mark {
 	color: #ff9011;
 }
 
+.example-wrap > pre.line-number {
+	border-color: #4a4949;
+}
+
 a.test-arrow {
 	background-color: rgba(78, 139, 202, 0.2);
 }

src/librustdoc/html/static/themes/light.css

@@ -227,6 +227,10 @@ pre.rust .question-mark {
 	color: #ff9011;
 }
 
+.example-wrap > pre.line-number {
+	border-color: #c7c7c7;
+}
+
 a.test-arrow {
 	background-color: rgba(78, 139, 202, 0.2);
 }

src/librustdoc/lib.rs

@@ -460,7 +460,7 @@ fn main_args(args: &[String]) -> isize {
     let externs = match parse_externs(&matches) {
         Ok(ex) => ex,
         Err(err) => {
-            diag.struct_err(&err.to_string()).emit();
+            diag.struct_err(&err).emit();
             return 1;
         }
     };

src/librustdoc/test.rs

@@ -208,7 +208,7 @@ fn run_test(test: &str, cratename: &str, filename: &FileName, line: usize,
     // needs to be the result of SourceMap::span_to_unmapped_path
     let input = config::Input::Str {
         name: filename.to_owned(),
-        input: test.to_owned(),
+        input: test,
     };
     let outputs = OutputTypes::new(&[(OutputType::Exe, None)]);
 
@@ -350,7 +350,7 @@ fn run_test(test: &str, cratename: &str, filename: &FileName, line: usize,
     let newpath = {
         let path = env::var_os(var).unwrap_or(OsString::new());
         let mut path = env::split_paths(&path).collect::<Vec<_>>();
-        path.insert(0, libdir.clone());
+        path.insert(0, libdir);
         env::join_paths(path).unwrap()
     };
     cmd.env(var, &newpath);

src/libsyntax/ext/base.rs

@@ -247,8 +247,13 @@ impl<F> AttrProcMacro for F
 
 /// Represents a thing that maps token trees to Macro Results
 pub trait TTMacroExpander {
-    fn expand<'cx>(&self, ecx: &'cx mut ExtCtxt, span: Span, input: TokenStream)
-                   -> Box<dyn MacResult+'cx>;
+    fn expand<'cx>(
+        &self,
+        ecx: &'cx mut ExtCtxt,
+        span: Span,
+        input: TokenStream,
+        def_span: Option<Span>,
+    ) -> Box<dyn MacResult+'cx>;
 }
 
 pub type MacroExpanderFn =
@@ -259,8 +264,13 @@ impl<F> TTMacroExpander for F
     where F: for<'cx> Fn(&'cx mut ExtCtxt, Span, &[tokenstream::TokenTree])
     -> Box<dyn MacResult+'cx>
 {
-    fn expand<'cx>(&self, ecx: &'cx mut ExtCtxt, span: Span, input: TokenStream)
-                   -> Box<dyn MacResult+'cx> {
+    fn expand<'cx>(
+        &self,
+        ecx: &'cx mut ExtCtxt,
+        span: Span,
+        input: TokenStream,
+        _def_span: Option<Span>,
+    ) -> Box<dyn MacResult+'cx> {
         struct AvoidInterpolatedIdents;
 
         impl Folder for AvoidInterpolatedIdents {

src/libsyntax/ext/expand.rs

@@ -764,7 +764,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                                                                     edition) {
                     dummy_span
                 } else {
-                    kind.make_from(expander.expand(self.cx, span, mac.node.stream()))
+                    kind.make_from(expander.expand(self.cx, span, mac.node.stream(), None))
                 }
             }
 
@@ -785,7 +785,12 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                                                                     edition) {
                     dummy_span
                 } else {
-                    kind.make_from(expander.expand(self.cx, span, mac.node.stream()))
+                    kind.make_from(expander.expand(
+                        self.cx,
+                        span,
+                        mac.node.stream(),
+                        def_info.map(|(_, s)| s),
+                    ))
                 }
             }
 
@@ -1036,10 +1041,28 @@ impl<'a> Parser<'a> {
             // Avoid emitting backtrace info twice.
             let def_site_span = self.span.with_ctxt(SyntaxContext::empty());
             let mut err = self.diagnostic().struct_span_err(def_site_span, &msg);
-            let msg = format!("caused by the macro expansion here; the usage \
-                               of `{}!` is likely invalid in {} context",
-                               macro_path, kind_name);
-            err.span_note(span, &msg).emit();
+            err.span_label(span, "caused by the macro expansion here");
+            let msg = format!(
+                "the usage of `{}!` is likely invalid in {} context",
+                macro_path,
+                kind_name,
+            );
+            err.note(&msg);
+            let semi_span = self.sess.source_map().next_point(span);
+
+            let semi_full_span = semi_span.to(self.sess.source_map().next_point(semi_span));
+            match self.sess.source_map().span_to_snippet(semi_full_span) {
+                Ok(ref snippet) if &snippet[..] != ";" && kind_name == "expression" => {
+                    err.span_suggestion_with_applicability(
+                        semi_span,
+                        "you might be missing a semicolon here",
+                        ";".to_owned(),
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                _ => {}
+            }
+            err.emit();
         }
     }
 }

src/libsyntax/ext/tt/macro_rules.rs

@@ -50,7 +50,12 @@ pub struct ParserAnyMacro<'a> {
 impl<'a> ParserAnyMacro<'a> {
     pub fn make(mut self: Box<ParserAnyMacro<'a>>, kind: AstFragmentKind) -> AstFragment {
         let ParserAnyMacro { site_span, macro_ident, ref mut parser } = *self;
-        let fragment = panictry!(parser.parse_ast_fragment(kind, true));
+        let fragment = panictry!(parser.parse_ast_fragment(kind, true).map_err(|mut e| {
+            if e.span.is_dummy() {  // Get around lack of span in error (#30128)
+                e.set_span(site_span);
+            }
+            e
+        }));
 
         // We allow semicolons at the end of expressions -- e.g. the semicolon in
         // `macro_rules! m { () => { panic!(); } }` isn't parsed by `.parse_expr()`,
@@ -74,16 +79,19 @@ struct MacroRulesMacroExpander {
 }
 
 impl TTMacroExpander for MacroRulesMacroExpander {
-    fn expand<'cx>(&self,
-                   cx: &'cx mut ExtCtxt,
-                   sp: Span,
-                   input: TokenStream)
-                   -> Box<dyn MacResult+'cx> {
+    fn expand<'cx>(
+        &self,
+        cx: &'cx mut ExtCtxt,
+        sp: Span,
+        input: TokenStream,
+        def_span: Option<Span>,
+    ) -> Box<dyn MacResult+'cx> {
         if !self.valid {
             return DummyResult::any(sp);
         }
         generic_extension(cx,
                           sp,
+                          def_span,
                           self.name,
                           input,
                           &self.lhses,
@@ -99,6 +107,7 @@ fn trace_macros_note(cx: &mut ExtCtxt, sp: Span, message: String) {
 /// Given `lhses` and `rhses`, this is the new macro we create
 fn generic_extension<'cx>(cx: &'cx mut ExtCtxt,
                           sp: Span,
+                          def_span: Option<Span>,
                           name: ast::Ident,
                           arg: TokenStream,
                           lhses: &[quoted::TokenTree],
@@ -133,8 +142,7 @@ fn generic_extension<'cx>(cx: &'cx mut ExtCtxt,
                 // Replace all the tokens for the corresponding positions in the macro, to maintain
                 // proper positions in error reporting, while maintaining the macro_backtrace.
                 if rhs_spans.len() == tts.len() {
-                    tts = tts.map_enumerated(|i, tt| {
-                        let mut tt = tt.clone();
+                    tts = tts.map_enumerated(|i, mut tt| {
                         let mut sp = rhs_spans[i];
                         sp = sp.with_ctxt(tt.span().ctxt());
                         tt.set_span(sp);
@@ -178,7 +186,14 @@ fn generic_extension<'cx>(cx: &'cx mut ExtCtxt,
     }
 
     let best_fail_msg = parse_failure_msg(best_fail_tok.expect("ran no matchers"));
-    let mut err = cx.struct_span_err(best_fail_spot.substitute_dummy(sp), &best_fail_msg);
+    let span = best_fail_spot.substitute_dummy(sp);
+    let mut err = cx.struct_span_err(span, &best_fail_msg);
+    err.span_label(span, best_fail_msg);
+    if let Some(sp) = def_span {
+        if cx.source_map().span_to_filename(sp).is_real() && !sp.is_dummy() {
+            err.span_label(cx.source_map().def_span(sp), "when calling this macro");
+        }
+    }
 
     // Check whether there's a missing comma in this macro call, like `println!("{}" a);`
     if let Some((arg, comma_span)) = arg.add_comma() {
@@ -189,7 +204,7 @@ fn generic_extension<'cx>(cx: &'cx mut ExtCtxt,
             };
             match TokenTree::parse(cx, lhs_tt, arg.clone()) {
                 Success(_) => {
-                    if comma_span == DUMMY_SP {
+                    if comma_span.is_dummy() {
                         err.note("you might be missing a comma");
                     } else {
                         err.span_suggestion_short_with_applicability(
@@ -792,15 +807,15 @@ fn check_matcher_core(sess: &ParseSess,
             if let TokenTree::MetaVarDecl(_, ref name, ref frag_spec) = *token {
                 for next_token in &suffix_first.tokens {
                     match is_in_follow(next_token, &frag_spec.as_str()) {
-                        Err((msg, help)) => {
+                        IsInFollow::Invalid(msg, help) => {
                             sess.span_diagnostic.struct_span_err(next_token.span(), &msg)
                                 .help(help).emit();
                             // don't bother reporting every source of
                             // conflict for a particular element of `last`.
                             continue 'each_last;
                         }
-                        Ok(true) => {}
-                        Ok(false) => {
+                        IsInFollow::Yes => {}
+                        IsInFollow::No(ref possible) => {
                             let may_be = if last.tokens.len() == 1 &&
                                 suffix_first.tokens.len() == 1
                             {
@@ -809,15 +824,41 @@ fn check_matcher_core(sess: &ParseSess,
                                 "may be"
                             };
 
-                            sess.span_diagnostic.span_err(
-                                next_token.span(),
+                            let sp = next_token.span();
+                            let mut err = sess.span_diagnostic.struct_span_err(
+                                sp,
                                 &format!("`${name}:{frag}` {may_be} followed by `{next}`, which \
                                           is not allowed for `{frag}` fragments",
                                          name=name,
                                          frag=frag_spec,
                                          next=quoted_tt_to_string(next_token),
-                                         may_be=may_be)
+                                         may_be=may_be),
                             );
+                            err.span_label(
+                                sp,
+                                format!("not allowed after `{}` fragments", frag_spec),
+                            );
+                            let msg = "allowed there are: ";
+                            match &possible[..] {
+                                &[] => {}
+                                &[t] => {
+                                    err.note(&format!(
+                                        "only {} is allowed after `{}` fragments",
+                                        t,
+                                        frag_spec,
+                                    ));
+                                }
+                                ts => {
+                                    err.note(&format!(
+                                        "{}{} or {}",
+                                        msg,
+                                        ts[..ts.len() - 1].iter().map(|s| *s)
+                                            .collect::<Vec<_>>().join(", "),
+                                        ts[ts.len() - 1],
+                                    ));
+                                }
+                            }
+                            err.emit();
                         }
                     }
                 }
@@ -860,6 +901,12 @@ fn frag_can_be_followed_by_any(frag: &str) -> bool {
     }
 }
 
+enum IsInFollow {
+    Yes,
+    No(Vec<&'static str>),
+    Invalid(String, &'static str),
+}
+
 /// True if `frag` can legally be followed by the token `tok`. For
 /// fragments that can consume an unbounded number of tokens, `tok`
 /// must be within a well-defined follow set. This is intended to
@@ -868,81 +915,99 @@ fn frag_can_be_followed_by_any(frag: &str) -> bool {
 /// break macros that were relying on that binary operator as a
 /// separator.
 // when changing this do not forget to update doc/book/macros.md!
-fn is_in_follow(tok: &quoted::TokenTree, frag: &str) -> Result<bool, (String, &'static str)> {
+fn is_in_follow(tok: &quoted::TokenTree, frag: &str) -> IsInFollow {
     use self::quoted::TokenTree;
 
     if let TokenTree::Token(_, token::CloseDelim(_)) = *tok {
         // closing a token tree can never be matched by any fragment;
         // iow, we always require that `(` and `)` match, etc.
-        Ok(true)
+        IsInFollow::Yes
     } else {
         match frag {
             "item" => {
                 // since items *must* be followed by either a `;` or a `}`, we can
                 // accept anything after them
-                Ok(true)
+                IsInFollow::Yes
             },
             "block" => {
                 // anything can follow block, the braces provide an easy boundary to
                 // maintain
-                Ok(true)
+                IsInFollow::Yes
             },
-            "stmt" | "expr"  => match *tok {
-                TokenTree::Token(_, ref tok) => match *tok {
-                    FatArrow | Comma | Semi => Ok(true),
-                    _ => Ok(false)
-                },
-                _ => Ok(false),
+            "stmt" | "expr"  => {
+                let tokens = vec!["`=>`", "`,`", "`;`"];
+                match *tok {
+                    TokenTree::Token(_, ref tok) => match *tok {
+                        FatArrow | Comma | Semi => IsInFollow::Yes,
+                        _ => IsInFollow::No(tokens),
+                    },
+                    _ => IsInFollow::No(tokens),
+                }
             },
-            "pat" => match *tok {
-                TokenTree::Token(_, ref tok) => match *tok {
-                    FatArrow | Comma | Eq | BinOp(token::Or) => Ok(true),
-                    Ident(i, false) if i.name == "if" || i.name == "in" => Ok(true),
-                    _ => Ok(false)
-                },
-                _ => Ok(false),
+            "pat" => {
+                let tokens = vec!["`=>`", "`,`", "`=`", "`|`", "`if`", "`in`"];
+                match *tok {
+                    TokenTree::Token(_, ref tok) => match *tok {
+                        FatArrow | Comma | Eq | BinOp(token::Or) => IsInFollow::Yes,
+                        Ident(i, false) if i.name == "if" || i.name == "in" => IsInFollow::Yes,
+                        _ => IsInFollow::No(tokens),
+                    },
+                    _ => IsInFollow::No(tokens),
+                }
             },
-            "path" | "ty" => match *tok {
-                TokenTree::Token(_, ref tok) => match *tok {
-                    OpenDelim(token::DelimToken::Brace) | OpenDelim(token::DelimToken::Bracket) |
-                    Comma | FatArrow | Colon | Eq | Gt | BinOp(token::Shr) | Semi |
-                    BinOp(token::Or) => Ok(true),
-                    Ident(i, false) if i.name == "as" || i.name == "where" => Ok(true),
-                    _ => Ok(false)
-                },
-                TokenTree::MetaVarDecl(_, _, frag) if frag.name == "block" => Ok(true),
-                _ => Ok(false),
+            "path" | "ty" => {
+                let tokens = vec![
+                    "`{`", "`[`", "`=>`", "`,`", "`>`","`=`", "`:`", "`;`", "`|`", "`as`",
+                    "`where`",
+                ];
+                match *tok {
+                    TokenTree::Token(_, ref tok) => match *tok {
+                        OpenDelim(token::DelimToken::Brace) |
+                        OpenDelim(token::DelimToken::Bracket) |
+                        Comma | FatArrow | Colon | Eq | Gt | BinOp(token::Shr) | Semi |
+                        BinOp(token::Or) => IsInFollow::Yes,
+                        Ident(i, false) if i.name == "as" || i.name == "where" => IsInFollow::Yes,
+                        _ => IsInFollow::No(tokens),
+                    },
+                    TokenTree::MetaVarDecl(_, _, frag) if frag.name == "block" => IsInFollow::Yes,
+                    _ => IsInFollow::No(tokens),
+                }
             },
             "ident" | "lifetime" => {
                 // being a single token, idents and lifetimes are harmless
-                Ok(true)
+                IsInFollow::Yes
             },
             "literal" => {
                 // literals may be of a single token, or two tokens (negative numbers)
-                Ok(true)
+                IsInFollow::Yes
             },
             "meta" | "tt" => {
                 // being either a single token or a delimited sequence, tt is
                 // harmless
-                Ok(true)
+                IsInFollow::Yes
             },
             "vis" => {
                 // Explicitly disallow `priv`, on the off chance it comes back.
+                let tokens = vec!["`,`", "an ident", "a type"];
                 match *tok {
                     TokenTree::Token(_, ref tok) => match *tok {
-                        Comma => Ok(true),
-                        Ident(i, is_raw) if is_raw || i.name != "priv" => Ok(true),
-                        ref tok => Ok(tok.can_begin_type())
+                        Comma => IsInFollow::Yes,
+                        Ident(i, is_raw) if is_raw || i.name != "priv" => IsInFollow::Yes,
+                        ref tok => if tok.can_begin_type() {
+                            IsInFollow::Yes
+                        } else {
+                            IsInFollow::No(tokens)
+                        }
                     },
                     TokenTree::MetaVarDecl(_, _, frag) if frag.name == "ident"
                                                        || frag.name == "ty"
-                                                       || frag.name == "path" => Ok(true),
-                    _ => Ok(false)
+                                                       || frag.name == "path" => IsInFollow::Yes,
+                    _ => IsInFollow::No(tokens),
                 }
             },
-            "" => Ok(true), // keywords::Invalid
-            _ => Err((format!("invalid fragment specifier `{}`", frag),
-                     VALID_FRAGMENT_NAMES_MSG))
+            "" => IsInFollow::Yes, // keywords::Invalid
+            _ => IsInFollow::Invalid(format!("invalid fragment specifier `{}`", frag),
+                                     VALID_FRAGMENT_NAMES_MSG),
         }
     }
 }

src/libsyntax/ext/tt/transcribe.rs

@@ -219,9 +219,9 @@ impl Add for LockstepIterSize {
             LockstepIterSize::Unconstrained => other,
             LockstepIterSize::Contradiction(_) => self,
             LockstepIterSize::Constraint(l_len, ref l_id) => match other {
-                LockstepIterSize::Unconstrained => self.clone(),
+                LockstepIterSize::Unconstrained => self,
                 LockstepIterSize::Contradiction(_) => other,
-                LockstepIterSize::Constraint(r_len, _) if l_len == r_len => self.clone(),
+                LockstepIterSize::Constraint(r_len, _) if l_len == r_len => self,
                 LockstepIterSize::Constraint(r_len, r_id) => {
                     let msg = format!("inconsistent lockstep iteration: \
                                        '{}' has {} items, but '{}' has {}",

src/libsyntax/test.rs

@@ -346,7 +346,7 @@ fn mk_main(cx: &mut TestCtxt) -> P<ast::Item> {
 
     test_runner.span = sp;
 
-    let test_main_path_expr = ecx.expr_path(test_runner.clone());
+    let test_main_path_expr = ecx.expr_path(test_runner);
     let call_test_main = ecx.expr_call(sp, test_main_path_expr,
                                        vec![mk_tests_slice(cx)]);
     let call_test_main = ecx.stmt_expr(call_test_main);

src/libsyntax_ext/deriving/cmp/partial_ord.rs

@@ -178,7 +178,7 @@ pub fn cs_partial_cmp(cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> P<
 
                 cx.expr_match(span, new, vec![eq_arm, neq_arm])
             },
-            equals_expr.clone(),
+            equals_expr,
             Box::new(|cx, span, (self_args, tag_tuple), _non_self_args| {
         if self_args.len() != 2 {
             cx.span_bug(span, "not exactly 2 arguments in `derive(PartialOrd)`")

src/libsyntax_ext/deriving/custom.rs

@@ -75,7 +75,7 @@ impl MultiItemModifier for ProcMacroDerive {
         // Mark attributes as known, and used.
         MarkAttrs(&self.attrs).visit_item(&item);
 
-        let input = __internal::new_token_stream(ecx.resolver.eliminate_crate_var(item.clone()));
+        let input = __internal::new_token_stream(ecx.resolver.eliminate_crate_var(item));
         let res = __internal::set_sess(ecx, || {
             let inner = self.inner;
             panic::catch_unwind(panic::AssertUnwindSafe(|| inner(input)))

src/libsyntax_pos/lib.rs

@@ -612,6 +612,17 @@ impl MultiSpan {
         &self.primary_spans
     }
 
+    /// Returns `true` if this contains only a dummy primary span with any hygienic context.
+    pub fn is_dummy(&self) -> bool {
+        let mut is_dummy = true;
+        for span in &self.primary_spans {
+            if !span.is_dummy() {
+                is_dummy = false;
+            }
+        }
+        is_dummy
+    }
+
     /// Replaces all occurrences of one Span with another. Used to move Spans in areas that don't
     /// display well (like std macros). Returns true if replacements occurred.
     pub fn replace(&mut self, before: Span, after: Span) -> bool {

src/test/run-pass-fulldeps/auxiliary/plugin_args.rs

@@ -38,7 +38,8 @@ impl TTMacroExpander for Expander {
     fn expand<'cx>(&self,
                    ecx: &'cx mut ExtCtxt,
                    sp: Span,
-                   _: TokenStream) -> Box<MacResult+'cx> {
+                   _: TokenStream,
+                   _: Option<Span>) -> Box<MacResult+'cx> {
         let args = self.args.iter().map(|i| pprust::meta_list_item_to_string(i))
             .collect::<Vec<_>>().join(", ");
         MacEager::expr(ecx.expr_str(sp, Symbol::intern(&args)))

src/test/rustdoc/deprecated-impls.rs

@@ -109,7 +109,7 @@ impl Bar for Foo2 {
 
     // @has - '//*[@class="stab deprecated"]' 'Deprecated since 1.0.5: fn_def_with_doc'
     // @has - 'fn_def_with_doc short'
-    // @!has - 'fn_def_with full'
+    // @!has - 'fn_def_with_doc full'
     fn fn_def_with_doc() {}
 
     // @has - '//*[@class="stab deprecated"]' 'Deprecated since 1.0.6: fn_def_without_doc'

src/test/rustdoc/dont-show-const-contents.rs

@@ -8,8 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// Test that we HTML-escape Rust expressions, where HTML special chars
-// can occur, and we know it's definitely not markup.
+// Test that the contents of constants are not displayed as part of the
+// documentation.
 
-// @!has escape_rust_expr/constant.CONST_S.html '//pre[@class="rust const"]' '"<script>"'
-pub const CONST_S: &'static str = "<script>";
+// @!has dont_show_const_contents/constant.CONST_S.html 'dont show this'
+pub const CONST_S: &'static str = "dont show this";

src/test/rustdoc/empty-section.rs

@@ -15,6 +15,6 @@
 pub struct Foo;
 
 // @has foo/struct.Foo.html
-// @!has - '//*[@class="synthetic-implementations"]' 'Auto Trait Implementations'
+// @!has - 'Auto Trait Implementations'
 impl !Send for Foo {}
 impl !Sync for Foo {}

src/test/rustdoc/hidden-methods.rs

@@ -28,12 +28,12 @@ pub mod hidden {
 
 // @has foo/struct.Foo.html
 // @!has - 'Methods'
-// @!has - 'impl Foo'
+// @!has - '//code' 'impl Foo'
 // @!has - 'this_should_be_hidden'
 pub use hidden::Foo;
 
 // @has foo/struct.Bar.html
 // @!has - 'Methods'
-// @!has - 'impl Bar'
+// @!has - '//code' 'impl Bar'
 // @!has - 'this_should_be_hidden'
 pub use hidden::Bar;

src/test/rustdoc/issue-13698.rs

@@ -22,5 +22,5 @@ pub trait Bar {
     fn bar(&self) {}
 }
 
-// @!has issue_13698/struct.Foo.html '//*[@id="method.foo"]' 'fn bar'
+// @!has issue_13698/struct.Foo.html '//*[@id="method.bar"]' 'fn bar'
 impl Bar for Foo {}

src/test/rustdoc/issue-46767.rs

@@ -15,4 +15,5 @@ mod private {
 }
 pub use self::private::Enum::*;
 
-// @!has foo/index.html '//a/@href' './private/index.html'
+// @!has-dir foo/private
+// @!has foo/index.html '//a/@href' 'private/index.html'

src/test/rustdoc/issue-55001.rs

@@ -0,0 +1,31 @@
+// Regression test for issue #55001. Previously, we would incorrectly
+// cache certain trait selection results when checking for blanket impls,
+// resulting in an ICE when we tried to confirm the cached ParamCandidate
+// against an obligation.
+
+pub struct DefaultAllocator;
+pub struct Standard;
+pub struct Inner;
+
+pub trait Rand {}
+
+pub trait Distribution<T> {}
+pub trait Allocator<N> {}
+
+impl<T> Rand for T where Standard: Distribution<T> {}
+
+impl<A> Distribution<Point<A>> for Standard
+where
+DefaultAllocator: Allocator<A>,
+Standard: Distribution<A> {}
+
+impl Distribution<Inner> for Standard {}
+
+
+pub struct Point<N>
+where DefaultAllocator: Allocator<N>
+{
+    field: N
+}
+
+fn main() {}

src/test/rustdoc/manual_impl.rs

@@ -35,7 +35,6 @@ pub trait T {
 // @has  - '//*[@class="docblock"]' 'Docs associated with the S1 trait a_method implementation.'
 // @!has - '//*[@class="docblock"]' 'Docs associated with the trait a_method definition.'
 // @has - '//*[@class="docblock"]' 'Docs associated with the trait b_method definition.'
-// @has - '//*[@class="docblock"]' 'Docs associated with the trait b_method definition.'
 // @has - '//*[@class="docblock"]' 'Docs associated with the trait c_method definition.'
 // @!has - '//*[@class="docblock"]' 'There is another line'
 // @has - '//*[@class="docblock"]' 'Read more'

src/test/rustdoc/playground-empty.rs

@@ -12,6 +12,8 @@
 
 #![doc(html_playground_url = "")]
 
+// compile-flags:-Z unstable-options --playground-url https://play.rust-lang.org/
+
 //! module docs
 //!
 //! ```

src/test/rustdoc/redirect.rs

@@ -43,6 +43,7 @@ mod private_no_inline {
 
 // @has redirect/index.html
 // @has - '//code' 'pub use private_no_inline::Qux'
-// @!has - '//code/a' 'Qux'
+// @!has - '//a' 'Qux'
+// @!has redirect/struct.Qux.html
 #[doc(no_inline)]
 pub use private_no_inline::Qux;

src/test/rustdoc/unneeded-trait-implementations-title.rs

@@ -12,4 +12,4 @@
 
 pub struct Bar;
 
-// @!has foo/struct.Bar.html '//*[@id="implementations"]'
+// @count foo/struct.Bar.html '//*[@id="implementations"]' 0

src/test/ui/consts/const-eval/double_promotion.rs

@@ -0,0 +1,17 @@
+// compile-pass
+
+#![feature(const_fn, rustc_attrs)]
+
+#[rustc_args_required_const(0)]
+pub const fn a(value: u8) -> u8 {
+    value
+}
+
+#[rustc_args_required_const(0)]
+pub fn b(_: u8) {
+    unimplemented!()
+}
+
+fn main() {
+    let _ = b(a(0));
+}

src/test/ui/editions/edition-keywords-2015-2015-parsing.stderr

@@ -2,13 +2,13 @@ error: no rules expected the token `r#async`
   --> $DIR/edition-keywords-2015-2015-parsing.rs:22:31
    |
 LL |     r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
-   |                               ^^^^^^^
+   |                               ^^^^^^^ no rules expected the token `r#async`
 
 error: no rules expected the token `async`
   --> $DIR/edition-keywords-2015-2015-parsing.rs:23:35
    |
 LL |     r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
-   |                                   ^^^^^
+   |                                   ^^^^^ no rules expected the token `async`
 
 error: aborting due to 2 previous errors
 

src/test/ui/editions/edition-keywords-2015-2018-parsing.stderr

@@ -2,13 +2,13 @@ error: no rules expected the token `r#async`
   --> $DIR/edition-keywords-2015-2018-parsing.rs:22:31
    |
 LL |     r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
-   |                               ^^^^^^^
+   |                               ^^^^^^^ no rules expected the token `r#async`
 
 error: no rules expected the token `async`
   --> $DIR/edition-keywords-2015-2018-parsing.rs:23:35
    |
 LL |     r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
-   |                                   ^^^^^
+   |                                   ^^^^^ no rules expected the token `async`
 
 error: aborting due to 2 previous errors
 

src/test/ui/editions/edition-keywords-2018-2015-parsing.stderr

@@ -14,13 +14,13 @@ error: no rules expected the token `r#async`
   --> $DIR/edition-keywords-2018-2015-parsing.rs:22:31
    |
 LL |     r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
-   |                               ^^^^^^^
+   |                               ^^^^^^^ no rules expected the token `r#async`
 
 error: no rules expected the token `async`
   --> $DIR/edition-keywords-2018-2015-parsing.rs:23:35
    |
 LL |     r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
-   |                                   ^^^^^
+   |                                   ^^^^^ no rules expected the token `async`
 
 error: expected one of `move`, `|`, or `||`, found `<eof>`
   --> <::edition_kw_macro_2015::passes_ident macros>:1:22

src/test/ui/editions/edition-keywords-2018-2018-parsing.stderr

@@ -14,13 +14,13 @@ error: no rules expected the token `r#async`
   --> $DIR/edition-keywords-2018-2018-parsing.rs:22:31
    |
 LL |     r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
-   |                               ^^^^^^^
+   |                               ^^^^^^^ no rules expected the token `r#async`
 
 error: no rules expected the token `async`
   --> $DIR/edition-keywords-2018-2018-parsing.rs:23:35
    |
 LL |     r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
-   |                                   ^^^^^
+   |                                   ^^^^^ no rules expected the token `async`
 
 error: expected one of `move`, `|`, or `||`, found `<eof>`
   --> <::edition_kw_macro_2018::passes_ident macros>:1:22

src/test/ui/empty/empty-comment.stderr

@@ -1,8 +1,11 @@
 error: unexpected end of macro invocation
   --> $DIR/empty-comment.rs:20:5
    |
+LL | macro_rules! one_arg_macro {
+   | -------------------------- when calling this macro
+...
 LL |     one_arg_macro!(/**/); //~ ERROR unexpected end
-   |     ^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^ unexpected end of macro invocation
 
 error: aborting due to previous error
 

src/test/ui/fail-simple.stderr

@@ -2,7 +2,7 @@ error: no rules expected the token `@`
   --> $DIR/fail-simple.rs:12:12
    |
 LL |     panic!(@); //~ ERROR no rules expected the token `@`
-   |            ^
+   |            ^ no rules expected the token `@`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-30007.stderr

@@ -3,12 +3,11 @@ error: macro expansion ignores token `;` and any following
    |
 LL |     () => ( String ; );     //~ ERROR macro expansion ignores token `;`
    |                    ^
-   |
-note: caused by the macro expansion here; the usage of `t!` is likely invalid in type context
-  --> $DIR/issue-30007.rs:16:16
-   |
+...
 LL |     let i: Vec<t!()>;
-   |                ^^^^
+   |                ---- caused by the macro expansion here
+   |
+   = note: the usage of `t!` is likely invalid in type context
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-7970a.stderr

@@ -1,8 +1,11 @@
 error: unexpected end of macro invocation
   --> $DIR/issue-7970a.rs:16:5
    |
+LL | macro_rules! one_arg_macro {
+   | -------------------------- when calling this macro
+...
 LL |     one_arg_macro!();
-   |     ^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^ unexpected end of macro invocation
 
 error: aborting due to previous error
 

src/test/ui/macros/macro-at-most-once-rep-2018-feature-gate.stderr

@@ -51,20 +51,29 @@ LL |     ($(a)?*) => {}
 error: no rules expected the token `?`
   --> $DIR/macro-at-most-once-rep-2018-feature-gate.rs:41:11
    |
+LL | macro_rules! foo {
+   | ---------------- when calling this macro
+...
 LL |     foo!(a?); //~ ERROR no rules expected the token `?`
-   |           ^
+   |           ^ no rules expected the token `?`
 
 error: no rules expected the token `?`
   --> $DIR/macro-at-most-once-rep-2018-feature-gate.rs:42:11
    |
+LL | macro_rules! foo {
+   | ---------------- when calling this macro
+...
 LL |     foo!(a?a); //~ ERROR no rules expected the token `?`
-   |           ^
+   |           ^ no rules expected the token `?`
 
 error: no rules expected the token `?`
   --> $DIR/macro-at-most-once-rep-2018-feature-gate.rs:43:11
    |
+LL | macro_rules! foo {
+   | ---------------- when calling this macro
+...
 LL |     foo!(a?a?a); //~ ERROR no rules expected the token `?`
-   |           ^
+   |           ^ no rules expected the token `?`
 
 error: aborting due to 10 previous errors
 

src/test/ui/macros/macro-at-most-once-rep-2018.stderr

@@ -7,68 +7,101 @@ LL |     ($(a),?) => {} //~ERROR the `?` macro repetition operator
 error: no rules expected the token `?`
   --> $DIR/macro-at-most-once-rep-2018.rs:36:11
    |
+LL | macro_rules! foo {
+   | ---------------- when calling this macro
+...
 LL |     foo!(a?); //~ ERROR no rules expected the token `?`
-   |           ^
+   |           ^ no rules expected the token `?`
 
 error: no rules expected the token `?`
   --> $DIR/macro-at-most-once-rep-2018.rs:37:11
    |
+LL | macro_rules! foo {
+   | ---------------- when calling this macro
+...
 LL |     foo!(a?a); //~ ERROR no rules expected the token `?`
-   |           ^
+   |           ^ no rules expected the token `?`
 
 error: no rules expected the token `?`
   --> $DIR/macro-at-most-once-rep-2018.rs:38:11
    |
+LL | macro_rules! foo {
+   | ---------------- when calling this macro
+...
 LL |     foo!(a?a?a); //~ ERROR no rules expected the token `?`
-   |           ^
+   |           ^ no rules expected the token `?`
 
 error: unexpected end of macro invocation
   --> $DIR/macro-at-most-once-rep-2018.rs:40:5
    |
+LL | macro_rules! barplus {
+   | -------------------- when calling this macro
+...
 LL |     barplus!(); //~ERROR unexpected end of macro invocation
-   |     ^^^^^^^^^^^
+   |     ^^^^^^^^^^^ unexpected end of macro invocation
 
 error: unexpected end of macro invocation
   --> $DIR/macro-at-most-once-rep-2018.rs:41:14
    |
+LL | macro_rules! barplus {
+   | -------------------- when calling this macro
+...
 LL |     barplus!(a); //~ERROR unexpected end of macro invocation
-   |              ^
+   |              ^ unexpected end of macro invocation
 
 error: no rules expected the token `?`
   --> $DIR/macro-at-most-once-rep-2018.rs:42:15
    |
+LL | macro_rules! barplus {
+   | -------------------- when calling this macro
+...
 LL |     barplus!(a?); //~ ERROR no rules expected the token `?`
-   |               ^
+   |               ^ no rules expected the token `?`
 
 error: no rules expected the token `?`
   --> $DIR/macro-at-most-once-rep-2018.rs:43:15
    |
+LL | macro_rules! barplus {
+   | -------------------- when calling this macro
+...
 LL |     barplus!(a?a); //~ ERROR no rules expected the token `?`
-   |               ^
+   |               ^ no rules expected the token `?`
 
 error: unexpected end of macro invocation
   --> $DIR/macro-at-most-once-rep-2018.rs:47:5
    |
+LL | macro_rules! barstar {
+   | -------------------- when calling this macro
+...
 LL |     barstar!(); //~ERROR unexpected end of macro invocation
-   |     ^^^^^^^^^^^
+   |     ^^^^^^^^^^^ unexpected end of macro invocation
 
 error: unexpected end of macro invocation
   --> $DIR/macro-at-most-once-rep-2018.rs:48:14
    |
+LL | macro_rules! barstar {
+   | -------------------- when calling this macro
+...
 LL |     barstar!(a); //~ERROR unexpected end of macro invocation
-   |              ^
+   |              ^ unexpected end of macro invocation
 
 error: no rules expected the token `?`
   --> $DIR/macro-at-most-once-rep-2018.rs:49:15
    |
+LL | macro_rules! barstar {
+   | -------------------- when calling this macro
+...
 LL |     barstar!(a?); //~ ERROR no rules expected the token `?`
-   |               ^
+   |               ^ no rules expected the token `?`
 
 error: no rules expected the token `?`
   --> $DIR/macro-at-most-once-rep-2018.rs:50:15
    |
+LL | macro_rules! barstar {
+   | -------------------- when calling this macro
+...
 LL |     barstar!(a?a); //~ ERROR no rules expected the token `?`
-   |               ^
+   |               ^ no rules expected the token `?`
 
 error: aborting due to 12 previous errors
 

src/test/ui/macros/macro-context.stderr

@@ -3,36 +3,33 @@ error: macro expansion ignores token `;` and any following
    |
 LL |     () => ( i ; typeof );   //~ ERROR expected expression, found reserved keyword `typeof`
    |               ^
-   |
-note: caused by the macro expansion here; the usage of `m!` is likely invalid in type context
-  --> $DIR/macro-context.rs:20:12
-   |
+...
 LL |     let a: m!();
-   |            ^^^^
+   |            ---- caused by the macro expansion here
+   |
+   = note: the usage of `m!` is likely invalid in type context
 
 error: macro expansion ignores token `typeof` and any following
   --> $DIR/macro-context.rs:13:17
    |
 LL |     () => ( i ; typeof );   //~ ERROR expected expression, found reserved keyword `typeof`
    |                 ^^^^^^
-   |
-note: caused by the macro expansion here; the usage of `m!` is likely invalid in expression context
-  --> $DIR/macro-context.rs:21:13
-   |
+...
 LL |     let i = m!();
-   |             ^^^^
+   |             ---- caused by the macro expansion here
+   |
+   = note: the usage of `m!` is likely invalid in expression context
 
 error: macro expansion ignores token `;` and any following
   --> $DIR/macro-context.rs:13:15
    |
 LL |     () => ( i ; typeof );   //~ ERROR expected expression, found reserved keyword `typeof`
    |               ^
-   |
-note: caused by the macro expansion here; the usage of `m!` is likely invalid in pattern context
-  --> $DIR/macro-context.rs:23:9
-   |
+...
 LL |         m!() => {}
-   |         ^^^^
+   |         ---- caused by the macro expansion here
+   |
+   = note: the usage of `m!` is likely invalid in pattern context
 
 error: expected expression, found reserved keyword `typeof`
   --> $DIR/macro-context.rs:13:17

src/test/ui/macros/macro-follow.stderr

@@ -2,511 +2,681 @@ error: `$p:pat` is followed by `(`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:17:14
    |
 LL |     ($p:pat ()) => {};       //~ERROR  `$p:pat` is followed by `(`
-   |              ^
+   |              ^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `[`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:18:14
    |
 LL |     ($p:pat []) => {};       //~ERROR  `$p:pat` is followed by `[`
-   |              ^
+   |              ^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `{`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:19:14
    |
 LL |     ($p:pat {}) => {};       //~ERROR  `$p:pat` is followed by `{`
-   |              ^
+   |              ^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `:`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:20:13
    |
 LL |     ($p:pat :) => {};        //~ERROR `$p:pat` is followed by `:`
-   |             ^
+   |             ^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `>`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:21:13
    |
 LL |     ($p:pat >) => {};        //~ERROR `$p:pat` is followed by `>`
-   |             ^
+   |             ^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `+`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:22:13
    |
 LL |     ($p:pat +) => {};        //~ERROR `$p:pat` is followed by `+`
-   |             ^
+   |             ^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `ident`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:23:13
    |
 LL |     ($p:pat ident) => {};    //~ERROR `$p:pat` is followed by `ident`
-   |             ^^^^^
+   |             ^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `$p:pat`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:24:13
    |
 LL |     ($p:pat $p:pat) => {};   //~ERROR `$p:pat` is followed by `$p:pat`
-   |             ^^^^^^
+   |             ^^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `$e:expr`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:25:13
    |
 LL |     ($p:pat $e:expr) => {};  //~ERROR `$p:pat` is followed by `$e:expr`
-   |             ^^^^^^^
+   |             ^^^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `$t:ty`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:26:13
    |
 LL |     ($p:pat $t:ty) => {};    //~ERROR `$p:pat` is followed by `$t:ty`
-   |             ^^^^^
+   |             ^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `$s:stmt`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:27:13
    |
 LL |     ($p:pat $s:stmt) => {};  //~ERROR `$p:pat` is followed by `$s:stmt`
-   |             ^^^^^^^
+   |             ^^^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `$p:path`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:28:13
    |
 LL |     ($p:pat $p:path) => {};  //~ERROR `$p:pat` is followed by `$p:path`
-   |             ^^^^^^^
+   |             ^^^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `$b:block`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:29:13
    |
 LL |     ($p:pat $b:block) => {}; //~ERROR `$p:pat` is followed by `$b:block`
-   |             ^^^^^^^^
+   |             ^^^^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `$i:ident`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:30:13
    |
 LL |     ($p:pat $i:ident) => {}; //~ERROR `$p:pat` is followed by `$i:ident`
-   |             ^^^^^^^^
+   |             ^^^^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `$t:tt`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:31:13
    |
 LL |     ($p:pat $t:tt) => {};    //~ERROR `$p:pat` is followed by `$t:tt`
-   |             ^^^^^
+   |             ^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `$i:item`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:32:13
    |
 LL |     ($p:pat $i:item) => {};  //~ERROR `$p:pat` is followed by `$i:item`
-   |             ^^^^^^^
+   |             ^^^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$p:pat` is followed by `$m:meta`, which is not allowed for `pat` fragments
   --> $DIR/macro-follow.rs:33:13
    |
 LL |     ($p:pat $m:meta) => {};  //~ERROR `$p:pat` is followed by `$m:meta`
-   |             ^^^^^^^
+   |             ^^^^^^^ not allowed after `pat` fragments
+   |
+   = note: allowed there are: `=>`, `,`, `=`, `|`, `if` or `in`
 
 error: `$e:expr` is followed by `(`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:37:15
    |
 LL |     ($e:expr ()) => {};       //~ERROR  `$e:expr` is followed by `(`
-   |               ^
+   |               ^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `[`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:38:15
    |
 LL |     ($e:expr []) => {};       //~ERROR  `$e:expr` is followed by `[`
-   |               ^
+   |               ^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `{`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:39:15
    |
 LL |     ($e:expr {}) => {};       //~ERROR  `$e:expr` is followed by `{`
-   |               ^
+   |               ^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `=`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:40:14
    |
 LL |     ($e:expr =) => {};        //~ERROR `$e:expr` is followed by `=`
-   |              ^
+   |              ^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `|`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:41:14
    |
 LL |     ($e:expr |) => {};        //~ERROR `$e:expr` is followed by `|`
-   |              ^
+   |              ^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `:`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:42:14
    |
 LL |     ($e:expr :) => {};        //~ERROR `$e:expr` is followed by `:`
-   |              ^
+   |              ^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `>`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:43:14
    |
 LL |     ($e:expr >) => {};        //~ERROR `$e:expr` is followed by `>`
-   |              ^
+   |              ^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `+`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:44:14
    |
 LL |     ($e:expr +) => {};        //~ERROR `$e:expr` is followed by `+`
-   |              ^
+   |              ^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `ident`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:45:14
    |
 LL |     ($e:expr ident) => {};    //~ERROR `$e:expr` is followed by `ident`
-   |              ^^^^^
+   |              ^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `if`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:46:14
    |
 LL |     ($e:expr if) => {};       //~ERROR `$e:expr` is followed by `if`
-   |              ^^
+   |              ^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `in`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:47:14
    |
 LL |     ($e:expr in) => {};       //~ERROR `$e:expr` is followed by `in`
-   |              ^^
+   |              ^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `$p:pat`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:48:14
    |
 LL |     ($e:expr $p:pat) => {};   //~ERROR `$e:expr` is followed by `$p:pat`
-   |              ^^^^^^
+   |              ^^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `$e:expr`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:49:14
    |
 LL |     ($e:expr $e:expr) => {};  //~ERROR `$e:expr` is followed by `$e:expr`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `$t:ty`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:50:14
    |
 LL |     ($e:expr $t:ty) => {};    //~ERROR `$e:expr` is followed by `$t:ty`
-   |              ^^^^^
+   |              ^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `$s:stmt`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:51:14
    |
 LL |     ($e:expr $s:stmt) => {};  //~ERROR `$e:expr` is followed by `$s:stmt`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `$p:path`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:52:14
    |
 LL |     ($e:expr $p:path) => {};  //~ERROR `$e:expr` is followed by `$p:path`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `$b:block`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:53:14
    |
 LL |     ($e:expr $b:block) => {}; //~ERROR `$e:expr` is followed by `$b:block`
-   |              ^^^^^^^^
+   |              ^^^^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `$i:ident`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:54:14
    |
 LL |     ($e:expr $i:ident) => {}; //~ERROR `$e:expr` is followed by `$i:ident`
-   |              ^^^^^^^^
+   |              ^^^^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `$t:tt`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:55:14
    |
 LL |     ($e:expr $t:tt) => {};    //~ERROR `$e:expr` is followed by `$t:tt`
-   |              ^^^^^
+   |              ^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `$i:item`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:56:14
    |
 LL |     ($e:expr $i:item) => {};  //~ERROR `$e:expr` is followed by `$i:item`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$e:expr` is followed by `$m:meta`, which is not allowed for `expr` fragments
   --> $DIR/macro-follow.rs:57:14
    |
 LL |     ($e:expr $m:meta) => {};  //~ERROR `$e:expr` is followed by `$m:meta`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$t:ty` is followed by `(`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:62:13
    |
 LL |     ($t:ty ()) => {};       //~ERROR  `$t:ty` is followed by `(`
-   |             ^
+   |             ^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `+`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:64:12
    |
 LL |     ($t:ty +) => {};        //~ERROR `$t:ty` is followed by `+`
-   |            ^
+   |            ^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `ident`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:65:12
    |
 LL |     ($t:ty ident) => {};    //~ERROR `$t:ty` is followed by `ident`
-   |            ^^^^^
+   |            ^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `if`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:66:12
    |
 LL |     ($t:ty if) => {};       //~ERROR `$t:ty` is followed by `if`
-   |            ^^
+   |            ^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `$p:pat`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:67:12
    |
 LL |     ($t:ty $p:pat) => {};   //~ERROR `$t:ty` is followed by `$p:pat`
-   |            ^^^^^^
+   |            ^^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `$e:expr`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:68:12
    |
 LL |     ($t:ty $e:expr) => {};  //~ERROR `$t:ty` is followed by `$e:expr`
-   |            ^^^^^^^
+   |            ^^^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `$t:ty`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:69:12
    |
 LL |     ($t:ty $t:ty) => {};    //~ERROR `$t:ty` is followed by `$t:ty`
-   |            ^^^^^
+   |            ^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `$s:stmt`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:70:12
    |
 LL |     ($t:ty $s:stmt) => {};  //~ERROR `$t:ty` is followed by `$s:stmt`
-   |            ^^^^^^^
+   |            ^^^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `$p:path`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:71:12
    |
 LL |     ($t:ty $p:path) => {};  //~ERROR `$t:ty` is followed by `$p:path`
-   |            ^^^^^^^
+   |            ^^^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `$i:ident`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:73:12
    |
 LL |     ($t:ty $i:ident) => {}; //~ERROR `$t:ty` is followed by `$i:ident`
-   |            ^^^^^^^^
+   |            ^^^^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `$t:tt`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:74:12
    |
 LL |     ($t:ty $t:tt) => {};    //~ERROR `$t:ty` is followed by `$t:tt`
-   |            ^^^^^
+   |            ^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `$i:item`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:75:12
    |
 LL |     ($t:ty $i:item) => {};  //~ERROR `$t:ty` is followed by `$i:item`
-   |            ^^^^^^^
+   |            ^^^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$t:ty` is followed by `$m:meta`, which is not allowed for `ty` fragments
   --> $DIR/macro-follow.rs:76:12
    |
 LL |     ($t:ty $m:meta) => {};  //~ERROR `$t:ty` is followed by `$m:meta`
-   |            ^^^^^^^
+   |            ^^^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$s:stmt` is followed by `(`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:80:15
    |
 LL |     ($s:stmt ()) => {};       //~ERROR  `$s:stmt` is followed by `(`
-   |               ^
+   |               ^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `[`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:81:15
    |
 LL |     ($s:stmt []) => {};       //~ERROR  `$s:stmt` is followed by `[`
-   |               ^
+   |               ^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `{`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:82:15
    |
 LL |     ($s:stmt {}) => {};       //~ERROR  `$s:stmt` is followed by `{`
-   |               ^
+   |               ^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `=`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:83:14
    |
 LL |     ($s:stmt =) => {};        //~ERROR `$s:stmt` is followed by `=`
-   |              ^
+   |              ^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `|`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:84:14
    |
 LL |     ($s:stmt |) => {};        //~ERROR `$s:stmt` is followed by `|`
-   |              ^
+   |              ^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `:`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:85:14
    |
 LL |     ($s:stmt :) => {};        //~ERROR `$s:stmt` is followed by `:`
-   |              ^
+   |              ^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `>`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:86:14
    |
 LL |     ($s:stmt >) => {};        //~ERROR `$s:stmt` is followed by `>`
-   |              ^
+   |              ^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `+`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:87:14
    |
 LL |     ($s:stmt +) => {};        //~ERROR `$s:stmt` is followed by `+`
-   |              ^
+   |              ^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `ident`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:88:14
    |
 LL |     ($s:stmt ident) => {};    //~ERROR `$s:stmt` is followed by `ident`
-   |              ^^^^^
+   |              ^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `if`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:89:14
    |
 LL |     ($s:stmt if) => {};       //~ERROR `$s:stmt` is followed by `if`
-   |              ^^
+   |              ^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `in`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:90:14
    |
 LL |     ($s:stmt in) => {};       //~ERROR `$s:stmt` is followed by `in`
-   |              ^^
+   |              ^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `$p:pat`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:91:14
    |
 LL |     ($s:stmt $p:pat) => {};   //~ERROR `$s:stmt` is followed by `$p:pat`
-   |              ^^^^^^
+   |              ^^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `$e:expr`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:92:14
    |
 LL |     ($s:stmt $e:expr) => {};  //~ERROR `$s:stmt` is followed by `$e:expr`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `$t:ty`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:93:14
    |
 LL |     ($s:stmt $t:ty) => {};    //~ERROR `$s:stmt` is followed by `$t:ty`
-   |              ^^^^^
+   |              ^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `$s:stmt`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:94:14
    |
 LL |     ($s:stmt $s:stmt) => {};  //~ERROR `$s:stmt` is followed by `$s:stmt`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `$p:path`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:95:14
    |
 LL |     ($s:stmt $p:path) => {};  //~ERROR `$s:stmt` is followed by `$p:path`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `$b:block`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:96:14
    |
 LL |     ($s:stmt $b:block) => {}; //~ERROR `$s:stmt` is followed by `$b:block`
-   |              ^^^^^^^^
+   |              ^^^^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `$i:ident`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:97:14
    |
 LL |     ($s:stmt $i:ident) => {}; //~ERROR `$s:stmt` is followed by `$i:ident`
-   |              ^^^^^^^^
+   |              ^^^^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `$t:tt`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:98:14
    |
 LL |     ($s:stmt $t:tt) => {};    //~ERROR `$s:stmt` is followed by `$t:tt`
-   |              ^^^^^
+   |              ^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `$i:item`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:99:14
    |
 LL |     ($s:stmt $i:item) => {};  //~ERROR `$s:stmt` is followed by `$i:item`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$s:stmt` is followed by `$m:meta`, which is not allowed for `stmt` fragments
   --> $DIR/macro-follow.rs:100:14
    |
 LL |     ($s:stmt $m:meta) => {};  //~ERROR `$s:stmt` is followed by `$m:meta`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `stmt` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$p:path` is followed by `(`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:104:15
    |
 LL |     ($p:path ()) => {};       //~ERROR  `$p:path` is followed by `(`
-   |               ^
+   |               ^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `+`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:106:14
    |
 LL |     ($p:path +) => {};        //~ERROR `$p:path` is followed by `+`
-   |              ^
+   |              ^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `ident`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:107:14
    |
 LL |     ($p:path ident) => {};    //~ERROR `$p:path` is followed by `ident`
-   |              ^^^^^
+   |              ^^^^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `if`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:108:14
    |
 LL |     ($p:path if) => {};       //~ERROR `$p:path` is followed by `if`
-   |              ^^
+   |              ^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `$p:pat`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:109:14
    |
 LL |     ($p:path $p:pat) => {};   //~ERROR `$p:path` is followed by `$p:pat`
-   |              ^^^^^^
+   |              ^^^^^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `$e:expr`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:110:14
    |
 LL |     ($p:path $e:expr) => {};  //~ERROR `$p:path` is followed by `$e:expr`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `$t:ty`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:111:14
    |
 LL |     ($p:path $t:ty) => {};    //~ERROR `$p:path` is followed by `$t:ty`
-   |              ^^^^^
+   |              ^^^^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `$s:stmt`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:112:14
    |
 LL |     ($p:path $s:stmt) => {};  //~ERROR `$p:path` is followed by `$s:stmt`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `$p:path`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:113:14
    |
 LL |     ($p:path $p:path) => {};  //~ERROR `$p:path` is followed by `$p:path`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `$i:ident`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:115:14
    |
 LL |     ($p:path $i:ident) => {}; //~ERROR `$p:path` is followed by `$i:ident`
-   |              ^^^^^^^^
+   |              ^^^^^^^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `$t:tt`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:116:14
    |
 LL |     ($p:path $t:tt) => {};    //~ERROR `$p:path` is followed by `$t:tt`
-   |              ^^^^^
+   |              ^^^^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `$i:item`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:117:14
    |
 LL |     ($p:path $i:item) => {};  //~ERROR `$p:path` is followed by `$i:item`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: `$p:path` is followed by `$m:meta`, which is not allowed for `path` fragments
   --> $DIR/macro-follow.rs:118:14
    |
 LL |     ($p:path $m:meta) => {};  //~ERROR `$p:path` is followed by `$m:meta`
-   |              ^^^^^^^
+   |              ^^^^^^^ not allowed after `path` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: aborting due to 85 previous errors
 

src/test/ui/macros/macro-followed-by-seq-bad.stderr

@@ -2,13 +2,17 @@ error: `$a:expr` is followed by `$b:tt`, which is not allowed for `expr` fragmen
   --> $DIR/macro-followed-by-seq-bad.rs:17:15
    |
 LL |   ( $a:expr $($b:tt)* ) => { }; //~ ERROR not allowed for `expr` fragments
-   |               ^^^^^
+   |               ^^^^^ not allowed after `expr` fragments
+   |
+   = note: allowed there are: `=>`, `,` or `;`
 
 error: `$a:ty` is followed by `$b:tt`, which is not allowed for `ty` fragments
   --> $DIR/macro-followed-by-seq-bad.rs:18:13
    |
 LL |   ( $a:ty $($b:tt)* ) => { };   //~ ERROR not allowed for `ty` fragments
-   |             ^^^^^
+   |             ^^^^^ not allowed after `ty` fragments
+   |
+   = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`
 
 error: aborting due to 2 previous errors
 

src/test/ui/macros/macro-in-expression-context-2.rs

@@ -0,0 +1,7 @@
+macro_rules! empty { () => () }
+
+fn main() {
+    match 42 {
+        _ => { empty!() }
+    };
+}

src/test/ui/macros/macro-in-expression-context-2.stderr

@@ -0,0 +1,8 @@
+error: expected expression, found `<eof>`
+  --> $DIR/macro-in-expression-context-2.rs:5:16
+   |
+LL |         _ => { empty!() }
+   |                ^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/macros/macro-in-expression-context.fixed

@@ -0,0 +1,15 @@
+// run-rustfix
+
+macro_rules! foo {
+    () => {
+        assert_eq!("A", "A");
+        assert_eq!("B", "B");
+    }
+    //~^^ ERROR macro expansion ignores token `assert_eq` and any following
+    //~| NOTE the usage of `foo!` is likely invalid in expression context
+}
+
+fn main() {
+    foo!();
+    //~^ NOTE caused by the macro expansion here
+}