Merge from rustc

src/bootstrap/src/core/build_steps/compile.rs

@@ -367,10 +367,13 @@ fn copy_self_contained_objects(
         let srcdir = builder
             .wasi_root(target)
             .unwrap_or_else(|| {
-                panic!("Target {:?} does not have a \"wasi-root\" key", target.triple)
+                panic!(
+                    "Target {:?} does not have a \"wasi-root\" key in Config.toml",
+                    target.triple
+                )
             })
             .join("lib")
-            .join(target.to_string().replace("-preview1", ""));
+            .join(target.to_string().replace("-preview1", "").replace("-preview2", ""));
         for &obj in &["libc.a", "crt1-command.o", "crt1-reactor.o"] {
             copy_and_stamp(
                 builder,

src/bootstrap/src/lib.rs

@@ -88,7 +88,7 @@ const EXTRA_CHECK_CFGS: &[(Option<Mode>, &str, Option<&[&'static str]>)] = &[
     (Some(Mode::Std), "no_sync", None),
     (Some(Mode::Std), "backtrace_in_libstd", None),
     /* Extra values not defined in the built-in targets yet, but used in std */
-    (Some(Mode::Std), "target_env", Some(&["libnx"])),
+    (Some(Mode::Std), "target_env", Some(&["libnx", "preview2"])),
     // (Some(Mode::Std), "target_os", Some(&[])),
     // #[cfg(bootstrap)] zkvm
     (Some(Mode::Std), "target_os", Some(&["zkvm"])),

src/doc/rustc/src/SUMMARY.md

@@ -59,6 +59,7 @@
     - [*-unknown-openbsd](platform-support/openbsd.md)
     - [\*-unknown-uefi](platform-support/unknown-uefi.md)
     - [wasm32-wasi-preview1-threads](platform-support/wasm32-wasi-preview1-threads.md)
+    - [wasm32-wasi-preview2](platform-support/wasm32-wasi-preview2.md)
     - [wasm64-unknown-unknown](platform-support/wasm64-unknown-unknown.md)
     - [\*-win7-windows-msvc](platform-support/win7-windows-msvc.md)
     - [x86_64-fortanix-unknown-sgx](platform-support/x86_64-fortanix-unknown-sgx.md)

src/doc/rustc/src/platform-support.md

@@ -360,6 +360,7 @@ target | std | host | notes
 `thumbv7a-pc-windows-msvc` | ? |  |
 `thumbv7a-uwp-windows-msvc` | ✓ |  |
 `thumbv7neon-unknown-linux-musleabihf` | ? |  | Thumb2-mode ARMv7-A Linux with NEON, MUSL
+[`wasm32-wasi-preview2`](platform-support/wasm32-wasi-preview2.md) | ✓ |  | WebAssembly
 [`wasm64-unknown-unknown`](platform-support/wasm64-unknown-unknown.md) | ? |  | WebAssembly
 `x86_64-apple-ios-macabi` | ✓ |  | Apple Catalyst on x86_64
 [`x86_64-apple-tvos`](platform-support/apple-tvos.md) | ? |  | x86 64-bit tvOS

src/doc/rustc/src/platform-support/wasm32-wasi-preview2.md

@@ -0,0 +1,30 @@
+# `wasm32-wasi-preview2`
+
+**Tier: 3**
+
+The `wasm32-wasi-preview2` target is a new and still (as of January 2024) an
+experimental target. This target is an extension to `wasm32-wasi-preview1` target,
+originally known as `wasm32-wasi`. It is the next evolution in the development of
+wasi (the [WebAssembly System Interface](https://wasi.dev)) that uses the WebAssembly
+[component model] to allow for a standardized set of syscalls that are intended to empower
+WebAssembly binaries with native host capabilities.
+
+[component model]: https://github.com/WebAssembly/component-model
+
+## Target maintainers
+
+- Alex Crichton, https://github.com/alexcrichton
+- Ryan Levick, https://github.com/rylev
+
+## Requirements
+
+This target is cross-compiled. The target supports `std` fully.
+
+## Platform requirements
+
+The WebAssembly runtime should support the wasi preview 2 API set.
+
+This target is not a stable target. This means that there are only a few engines
+which implement wasi preview 2, for example:
+
+* Wasmtime - `-W component-model`

src/doc/style-guide/src/editions.md

@@ -36,6 +36,10 @@ For a full history of changes in the Rust 2024 style edition, see the git
 history of the style guide. Notable changes in the Rust 2024 style edition
 include:
 
+- [#114764](https://github.com/rust-lang/rust/pull/114764) As the last member
+  of a delimited expression, delimited expressions are generally combinable,
+  regardless of the number of members. Previously only applied with exactly
+  one member (except for closures with explicit blocks).
 - Miscellaneous `rustfmt` bugfixes.
 - Use version-sort (sort `x8`, `x16`, `x32`, `x64`, `x128` in that order).
 - Change "ASCIIbetical" sort to Unicode-aware "non-lowercase before lowercase".

src/doc/style-guide/src/expressions.md

@@ -818,11 +818,11 @@ E.g., `&&Some(foo)` matches, `Foo(4, Bar)` does not.
 
 ## Combinable expressions
 
-Where a function call has a single argument, and that argument is formatted
-across multiple-lines, format the outer call as if it were a single-line call,
+When the last argument in a function call is formatted across
+multiple-lines, format the outer call as if it were a single-line call,
 if the result fits. Apply the same combining behaviour to any similar
 expressions which have multi-line, block-indented lists of sub-expressions
-delimited by parentheses (e.g., macros or tuple struct literals). E.g.,
+delimited by parentheses, brackets, or braces. E.g.,
 
 ```rust
 foo(bar(
@@ -848,20 +848,61 @@ let arr = [combinable(
     an_expr,
     another_expr,
 )];
+
+let x = Thing(an_expr, another_expr, match cond {
+    A => 1,
+    B => 2,
+});
+
+let x = format!("Stuff: {}", [
+    an_expr,
+    another_expr,
+]);
+
+let x = func(an_expr, another_expr, SomeStruct {
+    field: this_is_long,
+    another_field: 123,
+});
 ```
 
 Apply this behavior recursively.
 
-For a function with multiple arguments, if the last argument is a multi-line
-closure with an explicit block, there are no other closure arguments, and all
-the arguments and the first line of the closure fit on the first line, use the
-same combining behavior:
+If the last argument is a multi-line closure with an explicit block,
+only apply the combining behavior if there are no other closure arguments.
 
 ```rust
+// Combinable
 foo(first_arg, x, |param| {
     action();
     foo(param)
 })
+// Not combinable, because the closure is not the last argument
+foo(
+    first_arg,
+    |param| {
+        action();
+        foo(param)
+    },
+    whatever,
+)
+// Not combinable, because the first line of the closure does not fit
+foo(
+    first_arg,
+    x,
+    move |very_long_param_causing_line_to_overflow| -> Bar {
+        action();
+        foo(param)
+    },
+)
+// Not combinable, because there is more than one closure argument
+foo(
+    first_arg,
+    |x| x.bar(),
+    |param| {
+        action();
+        foo(param)
+    },
+)
 ```
 
 ## Ranges

src/librustdoc/html/templates/item_union.html

@@ -1,8 +1,8 @@
 <pre class="rust item-decl"><code>
-    {{ self.render_attributes_in_pre() | safe }}
-    {{ self.render_union() | safe }}
+    {{ self.render_attributes_in_pre()|safe }}
+    {{ self.render_union()|safe }}
 </code></pre>
-{{ self.document() | safe }}
+{{ self.document()|safe }}
 {% if self.fields_iter().peek().is_some() %}
     <h2 id="fields" class="fields section-header"> {# #}
         Fields<a href="#fields" class="anchor">§</a> {# #}
@@ -12,13 +12,13 @@
         <span id="structfield.{{ name }}" {#+ #}
             class="{{ ItemType::StructField +}} section-header"> {# #}
             <a href="#structfield.{{ name }}" class="anchor field">§</a> {# #}
-            <code>{{ name }}: {{+ self.print_ty(ty) | safe }}</code> {# #}
+            <code>{{ name }}: {{+ self.print_ty(ty)|safe }}</code> {# #}
         </span>
         {% if let Some(stability_class) = self.stability_field(field) %}
             <span class="stab {{ stability_class }}"></span>
         {% endif %}
-        {{ self.document_field(field) | safe }}
+        {{ self.document_field(field)|safe }}
     {% endfor %}
 {% endif %}
-{{ self.render_assoc_items() | safe }}
-{{ self.document_type_layout() | safe }}
+{{ self.render_assoc_items()|safe }}
+{{ self.document_type_layout()|safe }}

src/tools/clippy/tests/ui/crashes/ice-6254.rs

@@ -11,8 +11,6 @@ fn main() {
     // This used to cause an ICE (https://github.com/rust-lang/rust/issues/78071)
     match FOO_REF_REF {
         FOO_REF_REF => {},
-        //~^ ERROR: to use a constant of type `Foo` in a pattern, `Foo` must be annotated
-        //~| NOTE: for more information, see issue #62411 <https://github.com/rust-lang/ru
         Foo(_) => {},
     }
 }

src/tools/clippy/tests/ui/crashes/ice-6254.stderr

@@ -1,15 +0,0 @@
-error: to use a constant of type `Foo` in a pattern, `Foo` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/ice-6254.rs:13:9
-   |
-LL |         FOO_REF_REF => {},
-   |         ^^^^^^^^^^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #62411 <https://github.com/rust-lang/rust/issues/62411>
-   = note: the traits must be derived, manual `impl`s are not sufficient
-   = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralEq.html for details
-   = note: `-D indirect-structural-match` implied by `-D warnings`
-   = help: to override `-D warnings` add `#[allow(indirect_structural_match)]`
-
-error: aborting due to 1 previous error
-

src/tools/clippy/tests/ui/modulo_one.rs

@@ -33,7 +33,6 @@ fn main() {
     INT_MIN % NEG_ONE;
     //~^ ERROR: this operation will panic at runtime
     //~| ERROR: any number modulo -1 will panic/overflow or result in 0
-    // ONLY caught by rustc
+    // Not caught by lint, we don't look into static items, even if entirely immutable.
     INT_MIN % STATIC_NEG_ONE;
-    //~^ ERROR: this operation will panic at runtime
 }

src/tools/clippy/tests/ui/modulo_one.stderr

@@ -12,12 +12,6 @@ error: this operation will panic at runtime
 LL |     INT_MIN % NEG_ONE;
    |     ^^^^^^^^^^^^^^^^^ attempt to compute `i64::MIN % -1_i64`, which would overflow
 
-error: this operation will panic at runtime
-  --> $DIR/modulo_one.rs:37:5
-   |
-LL |     INT_MIN % STATIC_NEG_ONE;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^ attempt to compute `i64::MIN % -1_i64`, which would overflow
-
 error: any number modulo 1 will be 0
   --> $DIR/modulo_one.rs:8:5
    |
@@ -57,5 +51,5 @@ error: any number modulo -1 will panic/overflow or result in 0
 LL |     INT_MIN % NEG_ONE;
    |     ^^^^^^^^^^^^^^^^^
 
-error: aborting due to 9 previous errors
+error: aborting due to 8 previous errors
 

src/tools/compiletest/src/header.rs

@@ -1109,9 +1109,6 @@ fn ignore_lldb(config: &Config, line: &str) -> IgnoreDecision {
 }
 
 fn ignore_llvm(config: &Config, line: &str) -> IgnoreDecision {
-    if config.system_llvm && line.starts_with("no-system-llvm") {
-        return IgnoreDecision::Ignore { reason: "ignored when the system LLVM is used".into() };
-    }
     if let Some(needed_components) =
         config.parse_name_value_directive(line, "needs-llvm-components")
     {

src/tools/compiletest/src/header/tests.rs

@@ -242,15 +242,6 @@ fn aux_build() {
     );
 }
 
-#[test]
-fn no_system_llvm() {
-    let config: Config = cfg().system_llvm(false).build();
-    assert!(!check_ignore(&config, "// no-system-llvm"));
-
-    let config: Config = cfg().system_llvm(true).build();
-    assert!(check_ignore(&config, "// no-system-llvm"));
-}
-
 #[test]
 fn llvm_version() {
     let config: Config = cfg().llvm_version("8.1.2").build();
@@ -266,6 +257,18 @@ fn llvm_version() {
     assert!(!check_ignore(&config, "// min-llvm-version: 9.0"));
 }
 
+#[test]
+fn system_llvm_version() {
+    let config: Config = cfg().system_llvm(true).llvm_version("17.0.0").build();
+    assert!(check_ignore(&config, "// min-system-llvm-version: 18.0"));
+
+    let config: Config = cfg().system_llvm(true).llvm_version("18.0.0").build();
+    assert!(!check_ignore(&config, "// min-system-llvm-version: 18.0"));
+
+    let config: Config = cfg().llvm_version("17.0.0").build();
+    assert!(!check_ignore(&config, "// min-system-llvm-version: 18.0"));
+}
+
 #[test]
 fn ignore_target() {
     let config: Config = cfg().target("x86_64-unknown-linux-gnu").build();

src/tools/miri/src/machine.rs

@@ -3,6 +3,7 @@
 
 use std::borrow::Cow;
 use std::cell::{Cell, RefCell};
+use std::collections::hash_map::Entry;
 use std::fmt;
 use std::path::Path;
 use std::process;
@@ -10,6 +11,7 @@ use std::process;
 use either::Either;
 use rand::rngs::StdRng;
 use rand::SeedableRng;
+use rand::Rng;
 
 use rustc_ast::ast::Mutability;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
@@ -45,6 +47,11 @@ pub const SIGRTMIN: i32 = 34;
 /// `SIGRTMAX` - `SIGRTMIN` >= 8 (which is the value of `_POSIX_RTSIG_MAX`)
 pub const SIGRTMAX: i32 = 42;
 
+/// Each const has multiple addresses, but only this many. Since const allocations are never
+/// deallocated, choosing a new [`AllocId`] and thus base address for each evaluation would
+/// produce unbounded memory usage.
+const ADDRS_PER_CONST: usize = 16;
+
 /// Extra data stored with each stack frame
 pub struct FrameExtra<'tcx> {
     /// Extra data for the Borrow Tracker.
@@ -65,12 +72,18 @@ pub struct FrameExtra<'tcx> {
     /// optimization.
     /// This is used by `MiriMachine::current_span` and `MiriMachine::caller_span`
     pub is_user_relevant: bool,
+
+    /// We have a cache for the mapping from [`mir::Const`] to resulting [`AllocId`].
+    /// However, we don't want all frames to always get the same result, so we insert
+    /// an additional bit of "salt" into the cache key. This salt is fixed per-frame
+    /// so that within a call, a const will have a stable address.
+    salt: usize,
 }
 
 impl<'tcx> std::fmt::Debug for FrameExtra<'tcx> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         // Omitting `timing`, it does not support `Debug`.
-        let FrameExtra { borrow_tracker, catch_unwind, timing: _, is_user_relevant: _ } = self;
+        let FrameExtra { borrow_tracker, catch_unwind, timing: _, is_user_relevant: _, salt: _ } = self;
         f.debug_struct("FrameData")
             .field("borrow_tracker", borrow_tracker)
             .field("catch_unwind", catch_unwind)
@@ -80,7 +93,7 @@ impl<'tcx> std::fmt::Debug for FrameExtra<'tcx> {
 
 impl VisitProvenance for FrameExtra<'_> {
     fn visit_provenance(&self, visit: &mut VisitWith<'_>) {
-        let FrameExtra { catch_unwind, borrow_tracker, timing: _, is_user_relevant: _ } = self;
+        let FrameExtra { catch_unwind, borrow_tracker, timing: _, is_user_relevant: _, salt: _ } = self;
 
         catch_unwind.visit_provenance(visit);
         borrow_tracker.visit_provenance(visit);
@@ -552,6 +565,11 @@ pub struct MiriMachine<'mir, 'tcx> {
     /// The spans we will use to report where an allocation was created and deallocated in
     /// diagnostics.
     pub(crate) allocation_spans: RefCell<FxHashMap<AllocId, (Span, Option<Span>)>>,
+
+    /// Maps MIR consts to their evaluated result. We combine the const with a "salt" (`usize`)
+    /// that is fixed per stack frame; this lets us have sometimes different results for the
+    /// same const while ensuring consistent results within a single call.
+    const_cache: RefCell<FxHashMap<(mir::Const<'tcx>, usize), OpTy<'tcx, Provenance>>>,
 }
 
 impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {
@@ -677,6 +695,7 @@ impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {
             stack_size,
             collect_leak_backtraces: config.collect_leak_backtraces,
             allocation_spans: RefCell::new(FxHashMap::default()),
+            const_cache: RefCell::new(FxHashMap::default()),
         }
     }
 
@@ -788,6 +807,7 @@ impl VisitProvenance for MiriMachine<'_, '_> {
             stack_size: _,
             collect_leak_backtraces: _,
             allocation_spans: _,
+            const_cache: _,
         } = self;
 
         threads.visit_provenance(visit);
@@ -1345,6 +1365,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
             catch_unwind: None,
             timing,
             is_user_relevant: ecx.machine.is_user_relevant(&frame),
+            salt: ecx.machine.rng.borrow_mut().gen::<usize>() % ADDRS_PER_CONST,
         };
 
         Ok(frame.with_extra(extra))
@@ -1450,4 +1471,31 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
         ecx.machine.allocation_spans.borrow_mut().insert(alloc_id, (span, None));
         Ok(())
     }
+
+    fn eval_mir_constant<F>(
+        ecx: &InterpCx<'mir, 'tcx, Self>,
+        val: mir::Const<'tcx>,
+        span: Option<Span>,
+        layout: Option<TyAndLayout<'tcx>>,
+        eval: F,
+    ) -> InterpResult<'tcx, OpTy<'tcx, Self::Provenance>>
+    where
+        F: Fn(
+            &InterpCx<'mir, 'tcx, Self>,
+            mir::Const<'tcx>,
+            Option<Span>,
+            Option<TyAndLayout<'tcx>>,
+        ) -> InterpResult<'tcx, OpTy<'tcx, Self::Provenance>>,
+    {
+        let frame = ecx.active_thread_stack().last().unwrap();
+        let mut cache = ecx.machine.const_cache.borrow_mut();
+        match cache.entry((val, frame.extra.salt)) {
+            Entry::Vacant(ve) => {
+                let op = eval(ecx, val, span, layout)?;
+                ve.insert(op.clone());
+                Ok(op)
+            }
+            Entry::Occupied(oe) => Ok(oe.get().clone()),
+        }
+    }
 }

src/tools/miri/src/shims/intrinsics/mod.rs

@@ -5,6 +5,7 @@ use std::iter;
 
 use log::trace;
 
+use rand::Rng;
 use rustc_apfloat::{Float, Round};
 use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::{
@@ -141,6 +142,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 this.write_pointer(Pointer::new(ptr.provenance, masked_addr), dest)?;
             }
 
+            // We want to return either `true` or `false` at random, or else something like
+            // ```
+            // if !is_val_statically_known(0) { unreachable_unchecked(); }
+            // ```
+            // Would not be considered UB, or the other way around (`is_val_statically_known(0)`).
+            "is_val_statically_known" => {
+                let [_] = check_arg_count(args)?;
+                let branch: bool = this.machine.rng.get_mut().gen();
+                this.write_scalar(Scalar::from_bool(branch), dest)?;
+            }
+
             // Floating-point operations
             "fabsf32" => {
                 let [f] = check_arg_count(args)?;

src/tools/miri/tests/pass/const-addrs.rs

@@ -0,0 +1,38 @@
+// The const fn interpreter creates a new AllocId every time it evaluates any const.
+// If we do that in Miri, repeatedly evaluating a const causes unbounded memory use
+// we need to keep track of the base address for that AllocId, and the allocation is never
+// deallocated.
+// In Miri we explicitly store previously-assigned AllocIds for each const and ensure
+// that we only hand out a finite number of AllocIds per const.
+// MIR inlining will put every evaluation of the const we're repeatedly evaluting into the same
+// stack frame, breaking this test.
+//@compile-flags: -Zinline-mir=no
+#![feature(strict_provenance)]
+
+const EVALS: usize = 256;
+
+use std::collections::HashSet;
+fn main() {
+    let mut addrs = HashSet::new();
+    for _ in 0..EVALS {
+        addrs.insert(const_addr());
+    }
+    // Check that the const allocation has multiple base addresses
+    assert!(addrs.len() > 1);
+    // But also that we get a limited number of unique base addresses
+    assert!(addrs.len() < EVALS);
+
+    // Check that within a call we always produce the same address
+    let mut prev = 0;
+    for iter in 0..EVALS {
+        let addr = "test".as_bytes().as_ptr().addr();
+        if iter > 0 {
+            assert_eq!(prev, addr);
+        }
+        prev = addr;
+    }
+}
+
+fn const_addr() -> usize {
+    "test".as_bytes().as_ptr().addr()
+}

src/tools/miri/tests/pass/intrinsics.rs

@@ -33,6 +33,21 @@ fn main() {
     assert_eq!(intrinsics::likely(false), false);
     assert_eq!(intrinsics::unlikely(true), true);
 
+    let mut saw_true = false;
+    let mut saw_false = false;
+
+    for _ in 0..50 {
+        if unsafe { intrinsics::is_val_statically_known(0) } {
+            saw_true = true;
+        } else {
+            saw_false = true;
+        }
+    }
+    assert!(
+        saw_true && saw_false,
+        "`is_val_statically_known` failed to return both true and false. Congrats, you won the lottery!"
+    );
+
     intrinsics::forget(Bomb);
 
     let _v = intrinsics::discriminant_value(&Some(()));