Auto merge of #62684 - petrochenkov:scopevisit, r=davidtwco

resolve: Improve candidate search for unresolved macro suggestions

Use same scope visiting machinery for both collecting suggestion candidates and actually resolving the names.

The PR is better read in per-commit fashion with whitespace changes ignored (the first commit in particular moves some code around).

This should be the last pre-requisite for https://github.com/rust-lang/rust/pull/62086.
r? @davidtwco

src/test/ui/attributes/obsolete-attr.rs

@@ -1,7 +1,9 @@
 // Obsolete attributes fall back to feature gated custom attributes.
 
-#[ab_isize="stdcall"] extern {} //~ ERROR attribute `ab_isize` is currently unknown
+#[ab_isize="stdcall"] extern {}
+//~^ ERROR cannot find attribute macro `ab_isize` in this scope
 
-#[fixed_stack_segment] fn f() {} //~ ERROR attribute `fixed_stack_segment` is currently unknown
+#[fixed_stack_segment] fn f() {}
+//~^ ERROR cannot find attribute macro `fixed_stack_segment` in this scope
 
 fn main() {}

src/test/ui/attributes/obsolete-attr.stderr

@@ -1,21 +1,14 @@
-error[E0658]: The attribute `fixed_stack_segment` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/obsolete-attr.rs:5:3
+error: cannot find attribute macro `fixed_stack_segment` in this scope
+  --> $DIR/obsolete-attr.rs:6:3
    |
 LL | #[fixed_stack_segment] fn f() {}
    |   ^^^^^^^^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `ab_isize` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `ab_isize` in this scope
   --> $DIR/obsolete-attr.rs:3:3
    |
 LL | #[ab_isize="stdcall"] extern {}
    |   ^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/attributes/unknown-attr.rs

@@ -2,8 +2,11 @@
 
 #![feature(custom_inner_attributes)]
 
-#![mutable_doc] //~ ERROR attribute `mutable_doc` is currently unknown
+#![mutable_doc]
+//~^ ERROR cannot find attribute macro `mutable_doc` in this scope
 
-#[dance] mod a {} //~ ERROR attribute `dance` is currently unknown
+#[dance] mod a {}
+//~^ ERROR cannot find attribute macro `dance` in this scope
 
-#[dance] fn main() {} //~ ERROR attribute `dance` is currently unknown
+#[dance] fn main() {}
+//~^ ERROR cannot find attribute macro `dance` in this scope

src/test/ui/attributes/unknown-attr.stderr

@@ -1,30 +1,20 @@
-error[E0658]: The attribute `mutable_doc` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `mutable_doc` in this scope
   --> $DIR/unknown-attr.rs:5:4
    |
 LL | #![mutable_doc]
    |    ^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `dance` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/unknown-attr.rs:7:3
+error: cannot find attribute macro `dance` in this scope
+  --> $DIR/unknown-attr.rs:8:3
    |
 LL | #[dance] mod a {}
    |   ^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `dance` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/unknown-attr.rs:9:3
+error: cannot find attribute macro `dance` in this scope
+  --> $DIR/unknown-attr.rs:11:3
    |
 LL | #[dance] fn main() {}
    |   ^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/conditional-compilation/cfg-attr-unknown-attribute-macro-expansion.rs

@@ -1,6 +1,7 @@
 macro_rules! foo {
     () => {
-        #[cfg_attr(all(), unknown)] //~ ERROR `unknown` is currently unknown
+        #[cfg_attr(all(), unknown)]
+        //~^ ERROR cannot find attribute macro `unknown` in this scope
         fn foo() {}
     }
 }

src/test/ui/conditional-compilation/cfg-attr-unknown-attribute-macro-expansion.stderr

@@ -1,4 +1,4 @@
-error[E0658]: The attribute `unknown` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `unknown` in this scope
   --> $DIR/cfg-attr-unknown-attribute-macro-expansion.rs:3:27
    |
 LL |         #[cfg_attr(all(), unknown)]
@@ -6,10 +6,6 @@ LL |         #[cfg_attr(all(), unknown)]
 ...
 LL | foo!();
    | ------- in this macro invocation
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/custom_attribute.rs

@@ -1,9 +1,9 @@
 #![feature(stmt_expr_attributes)]
 
-#[foo] //~ ERROR The attribute `foo`
+#[foo] //~ ERROR cannot find attribute macro `foo` in this scope
 fn main() {
-    #[foo] //~ ERROR The attribute `foo`
+    #[foo] //~ ERROR cannot find attribute macro `foo` in this scope
     let x = ();
-    #[foo] //~ ERROR The attribute `foo`
+    #[foo] //~ ERROR cannot find attribute macro `foo` in this scope
     x
 }

src/test/ui/custom_attribute.stderr

@@ -1,30 +1,20 @@
-error[E0658]: The attribute `foo` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `foo` in this scope
   --> $DIR/custom_attribute.rs:3:3
    |
 LL | #[foo]
    |   ^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `foo` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `foo` in this scope
   --> $DIR/custom_attribute.rs:5:7
    |
 LL |     #[foo]
    |       ^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `foo` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `foo` in this scope
   --> $DIR/custom_attribute.rs:7:7
    |
 LL |     #[foo]
    |       ^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/derives/deriving-meta-unknown-trait.stderr

@@ -2,7 +2,7 @@ error: cannot find derive macro `Eqr` in this scope
   --> $DIR/deriving-meta-unknown-trait.rs:1:10
    |
 LL | #[derive(Eqr)]
-   |          ^^^ help: try: `Eq`
+   |          ^^^ help: a derive macro with a similar name exists: `Eq`
 
 error: aborting due to previous error
 

src/test/ui/feature-gates/feature-gate-custom_attribute.rs

@@ -1,23 +1,18 @@
 // Check that literals in attributes parse just fine.
 
+#[fake_attr] //~ ERROR cannot find attribute macro `fake_attr` in this scope
+#[fake_attr(100)] //~ ERROR cannot find attribute macro `fake_attr` in this scope
+#[fake_attr(1, 2, 3)] //~ ERROR cannot find attribute macro `fake_attr` in this scope
+#[fake_attr("hello")] //~ ERROR cannot find attribute macro `fake_attr` in this scope
+#[fake_attr(name = "hello")] //~ ERROR cannot find attribute macro `fake_attr` in this scope
+#[fake_attr(1, "hi", key = 12, true, false)] //~ ERROR cannot find attribute macro `fake_attr` in th
+#[fake_attr(key = "hello", val = 10)] //~ ERROR cannot find attribute macro `fake_attr` in this scop
+#[fake_attr(key("hello"), val(10))] //~ ERROR cannot find attribute macro `fake_attr` in this scope
+#[fake_attr(enabled = true, disabled = false)] //~ ERROR cannot find attribute macro `fake_attr` in
+#[fake_attr(true)] //~ ERROR cannot find attribute macro `fake_attr` in this scope
+#[fake_attr(pi = 3.14159)] //~ ERROR cannot find attribute macro `fake_attr` in this scope
+#[fake_attr(b"hi")] //~ ERROR cannot find attribute macro `fake_attr` in this scope
+#[fake_doc(r"doc")] //~ ERROR cannot find attribute macro `fake_doc` in this scope
+struct Q {}
 
-#![allow(dead_code)]
-#![allow(unused_variables)]
-
-#[fake_attr] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr(100)] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr(1, 2, 3)] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr("hello")] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr(name = "hello")] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr(1, "hi", key = 12, true, false)] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr(key = "hello", val = 10)] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr(key("hello"), val(10))] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr(enabled = true, disabled = false)] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr(true)] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr(pi = 3.14159)] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_attr(b"hi")] //~ ERROR attribute `fake_attr` is currently unknown
-#[fake_doc(r"doc")] //~ ERROR attribute `fake_doc` is currently unknown
-struct Q {  }
-
-
-fn main() { }
+fn main() {}

src/test/ui/feature-gates/feature-gate-custom_attribute.stderr

@@ -1,120 +1,80 @@
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:7:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:3:3
    |
 LL | #[fake_attr]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:8:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:4:3
    |
 LL | #[fake_attr(100)]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:9:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:5:3
    |
 LL | #[fake_attr(1, 2, 3)]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:10:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:6:3
    |
 LL | #[fake_attr("hello")]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:11:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:7:3
    |
 LL | #[fake_attr(name = "hello")]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:12:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:8:3
    |
 LL | #[fake_attr(1, "hi", key = 12, true, false)]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:13:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:9:3
    |
 LL | #[fake_attr(key = "hello", val = 10)]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:14:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:10:3
    |
 LL | #[fake_attr(key("hello"), val(10))]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:15:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:11:3
    |
 LL | #[fake_attr(enabled = true, disabled = false)]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:16:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:12:3
    |
 LL | #[fake_attr(true)]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:17:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:13:3
    |
 LL | #[fake_attr(pi = 3.14159)]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:18:3
+error: cannot find attribute macro `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:14:3
    |
 LL | #[fake_attr(b"hi")]
    |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `fake_doc` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/feature-gate-custom_attribute.rs:19:3
+error: cannot find attribute macro `fake_doc` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:15:3
    |
 LL | #[fake_doc(r"doc")]
    |   ^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: aborting due to 13 previous errors
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/feature-gates/feature-gate-rustc-attrs.rs

@@ -19,5 +19,5 @@ fn g() {}
 //~^ ERROR used by the test suite
 #[rustc_unknown]
 //~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
-//~| ERROR attribute `rustc_unknown` is currently unknown
+//~| ERROR cannot find attribute macro `rustc_unknown` in this scope
 fn main() {}

src/test/ui/feature-gates/feature-gate-rustc-attrs.stderr

@@ -37,14 +37,11 @@ LL | #[rustc_unknown]
    = note: for more information, see https://github.com/rust-lang/rust/issues/29642
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
 
-error[E0658]: The attribute `rustc_unknown` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `rustc_unknown` in this scope
   --> $DIR/feature-gate-rustc-attrs.rs:20:3
    |
 LL | #[rustc_unknown]
    |   ^^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error[E0658]: used by the test suite
   --> $DIR/feature-gate-rustc-attrs.rs:18:1

src/test/ui/hygiene/no_implicit_prelude-2018.stderr

@@ -3,8 +3,6 @@ error: cannot find macro `print!` in this scope
    |
 LL |         print!();
    |         ^^^^^
-   |
-   = help: have you added the `#[macro_use]` on the module/import?
 
 error: aborting due to previous error
 

src/test/ui/hygiene/no_implicit_prelude.stderr

@@ -13,7 +13,6 @@ error: cannot find macro `panic!` in this scope
 LL |         assert_eq!(0, 0);
    |         ^^^^^^^^^^^^^^^^^
    |
-   = help: have you added the `#[macro_use]` on the module/import?
    = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
 
 error[E0599]: no method named `clone` found for type `()` in the current scope

src/test/ui/hygiene/rustc-macro-transparency.rs

@@ -26,6 +26,6 @@ fn main() {
     Opaque; //~ ERROR cannot find value `Opaque` in this scope
 
     transparent; // OK
-    semitransparent; //~ ERROR cannot find value `semitransparent` in this scope
-    opaque; //~ ERROR cannot find value `opaque` in this scope
+    semitransparent; //~ ERROR expected value, found macro `semitransparent`
+    opaque; //~ ERROR expected value, found macro `opaque`
 }

src/test/ui/hygiene/rustc-macro-transparency.stderr

@@ -4,18 +4,19 @@ error[E0425]: cannot find value `Opaque` in this scope
 LL |     Opaque;
    |     ^^^^^^ help: a local variable with a similar name exists: `opaque`
 
-error[E0425]: cannot find value `semitransparent` in this scope
+error[E0423]: expected value, found macro `semitransparent`
   --> $DIR/rustc-macro-transparency.rs:29:5
    |
 LL |     semitransparent;
-   |     ^^^^^^^^^^^^^^^ not found in this scope
+   |     ^^^^^^^^^^^^^^^ help: use `!` to invoke the macro: `semitransparent!`
 
-error[E0425]: cannot find value `opaque` in this scope
+error[E0423]: expected value, found macro `opaque`
   --> $DIR/rustc-macro-transparency.rs:30:5
    |
 LL |     opaque;
-   |     ^^^^^^ not found in this scope
+   |     ^^^^^^ help: use `!` to invoke the macro: `opaque!`
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0425`.
+Some errors have detailed explanations: E0423, E0425.
+For more information about an error, try `rustc --explain E0423`.

src/test/ui/impl-trait/universal_wrong_bounds.rs

@@ -6,9 +6,8 @@ fn foo(f: impl Display + Clone) -> String {
     wants_clone(f);
 }
 
-fn wants_debug(g: impl Debug) { } //~ ERROR cannot find
-fn wants_display(g: impl Debug) { } //~ ERROR cannot find
+fn wants_debug(g: impl Debug) { } //~ ERROR expected trait, found derive macro `Debug`
+fn wants_display(g: impl Debug) { } //~ ERROR expected trait, found derive macro `Debug`
 fn wants_clone(g: impl Clone) { }
 
-fn main() {
-}
+fn main() {}

src/test/ui/impl-trait/universal_wrong_bounds.stderr

@@ -1,23 +1,23 @@
-error[E0405]: cannot find trait `Debug` in this scope
+error[E0404]: expected trait, found derive macro `Debug`
   --> $DIR/universal_wrong_bounds.rs:9:24
    |
 LL | fn wants_debug(g: impl Debug) { }
-   |                        ^^^^^ not found in this scope
-help: possible candidate is found in another module, you can import it into scope
+   |                        ^^^^^ not a trait
+help: possible better candidate is found in another module, you can import it into scope
    |
 LL | use std::fmt::Debug;
    |
 
-error[E0405]: cannot find trait `Debug` in this scope
+error[E0404]: expected trait, found derive macro `Debug`
   --> $DIR/universal_wrong_bounds.rs:10:26
    |
 LL | fn wants_display(g: impl Debug) { }
-   |                          ^^^^^ not found in this scope
-help: possible candidate is found in another module, you can import it into scope
+   |                          ^^^^^ not a trait
+help: possible better candidate is found in another module, you can import it into scope
    |
 LL | use std::fmt::Debug;
    |
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0405`.
+For more information about this error, try `rustc --explain E0404`.

src/test/ui/issues/issue-32655.rs

@@ -1,9 +1,6 @@
-#![allow(dead_code)]
-#![feature(rustc_attrs)]
-
 macro_rules! foo (
     () => (
-        #[derive_Clone] //~ ERROR attribute `derive_Clone` is currently unknown
+        #[derive_Clone] //~ ERROR cannot find attribute macro `derive_Clone` in this scope
         struct T;
     );
 );
@@ -15,7 +12,7 @@ macro_rules! bar (
 foo!();
 
 bar!(
-    #[derive_Clone] //~ ERROR attribute `derive_Clone` is currently unknown
+    #[derive_Clone] //~ ERROR cannot find attribute macro `derive_Clone` in this scope
     struct S;
 );
 

src/test/ui/issues/issue-32655.stderr

@@ -1,24 +1,17 @@
-error[E0658]: The attribute `derive_Clone` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/issue-32655.rs:6:11
+error: cannot find attribute macro `derive_Clone` in this scope
+  --> $DIR/issue-32655.rs:3:11
    |
 LL |         #[derive_Clone]
    |           ^^^^^^^^^^^^
 ...
 LL | foo!();
    | ------- in this macro invocation
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
-error[E0658]: The attribute `derive_Clone` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/issue-32655.rs:18:7
+error: cannot find attribute macro `derive_Clone` in this scope
+  --> $DIR/issue-32655.rs:15:7
    |
 LL |     #[derive_Clone]
    |       ^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/issues/issue-37534.rs

@@ -1,5 +1,5 @@
 struct Foo<T: ?Hash> { }
-//~^ ERROR cannot find trait `Hash` in this scope
+//~^ ERROR expected trait, found derive macro `Hash`
 //~^^ ERROR parameter `T` is never used
 //~^^^ WARN default bound relaxed for a type parameter, but this does nothing
 

src/test/ui/issues/issue-37534.stderr

@@ -1,9 +1,9 @@
-error[E0405]: cannot find trait `Hash` in this scope
+error[E0404]: expected trait, found derive macro `Hash`
   --> $DIR/issue-37534.rs:1:16
    |
 LL | struct Foo<T: ?Hash> { }
-   |                ^^^^ not found in this scope
-help: possible candidate is found in another module, you can import it into scope
+   |                ^^^^ not a trait
+help: possible better candidate is found in another module, you can import it into scope
    |
 LL | use std::hash::Hash;
    |
@@ -24,5 +24,5 @@ LL | struct Foo<T: ?Hash> { }
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0392, E0405.
+Some errors have detailed explanations: E0392, E0404.
 For more information about an error, try `rustc --explain E0392`.

src/test/ui/issues/issue-49074.rs

@@ -1,7 +1,7 @@
 // Check that unknown attribute error is shown even if there are unresolved macros.
 
 #[marco_use] // typo
-//~^ ERROR The attribute `marco_use` is currently unknown to the compiler
+//~^ ERROR cannot find attribute macro `marco_use` in this scope
 mod foo {
     macro_rules! bar {
         () => ();

src/test/ui/issues/issue-49074.stderr

@@ -1,11 +1,8 @@
-error[E0658]: The attribute `marco_use` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `marco_use` in this scope
   --> $DIR/issue-49074.rs:3:3
    |
 LL | #[marco_use] // typo
    |   ^^^^^^^^^ help: a built-in attribute with a similar name exists: `macro_use`
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: cannot find macro `bar!` in this scope
   --> $DIR/issue-49074.rs:12:4
@@ -17,4 +14,3 @@ LL |    bar!();
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/macros/macro-name-typo.stderr

@@ -2,7 +2,7 @@ error: cannot find macro `printlx!` in this scope
   --> $DIR/macro-name-typo.rs:2:5
    |
 LL |     printlx!("oh noes!");
-   |     ^^^^^^^ help: you could try the macro: `println`
+   |     ^^^^^^^ help: a macro with a similar name exists: `println`
 
 error: aborting due to previous error
 

src/test/ui/macros/macro-path-prelude-fail-3.stderr

@@ -2,7 +2,7 @@ error: cannot find macro `inline!` in this scope
   --> $DIR/macro-path-prelude-fail-3.rs:2:5
    |
 LL |     inline!();
-   |     ^^^^^^ help: you could try the macro: `line`
+   |     ^^^^^^ help: a macro with a similar name exists: `line`
 
 error: aborting due to previous error
 

src/test/ui/macros/macro-reexport-removed.rs

@@ -2,7 +2,7 @@
 
 #![feature(macro_reexport)] //~ ERROR feature has been removed
 
-#[macro_reexport(macro_one)] //~ ERROR attribute `macro_reexport` is currently unknown
+#[macro_reexport(macro_one)] //~ ERROR cannot find attribute macro `macro_reexport` in this scope
 extern crate two_macros;
 
 fn main() {}

src/test/ui/macros/macro-reexport-removed.stderr

@@ -10,16 +10,12 @@ note: subsumed by `pub use`
 LL | #![feature(macro_reexport)]
    |            ^^^^^^^^^^^^^^
 
-error[E0658]: The attribute `macro_reexport` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `macro_reexport` in this scope
   --> $DIR/macro-reexport-removed.rs:5:3
    |
 LL | #[macro_reexport(macro_one)]
    |   ^^^^^^^^^^^^^^ help: a built-in attribute with a similar name exists: `macro_export`
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0557, E0658.
-For more information about an error, try `rustc --explain E0557`.
+For more information about this error, try `rustc --explain E0557`.

src/test/ui/macros/macro-use-wrong-name.stderr

@@ -2,7 +2,7 @@ error: cannot find macro `macro_two!` in this scope
   --> $DIR/macro-use-wrong-name.rs:7:5
    |
 LL |     macro_two!();
-   |     ^^^^^^^^^ help: you could try the macro: `macro_one`
+   |     ^^^^^^^^^ help: a macro with a similar name exists: `macro_one`
 
 error: aborting due to previous error
 

src/test/ui/macros/macro_undefined.stderr

@@ -2,7 +2,7 @@ error: cannot find macro `k!` in this scope
   --> $DIR/macro_undefined.rs:11:5
    |
 LL |     k!();
-   |     ^ help: you could try the macro: `kl`
+   |     ^ help: a macro with a similar name exists: `kl`
 
 error: aborting due to previous error
 

src/test/ui/no-implicit-prelude-nested.rs

@@ -9,7 +9,7 @@ mod foo {
     mod baz {
         struct Test;
         impl Add for Test {} //~ ERROR cannot find trait `Add` in this scope
-        impl Clone for Test {} //~ ERROR cannot find trait `Clone` in this scope
+        impl Clone for Test {} //~ ERROR expected trait, found derive macro `Clone`
         impl Iterator for Test {} //~ ERROR cannot find trait `Iterator` in this scope
         impl ToString for Test {} //~ ERROR cannot find trait `ToString` in this scope
         impl Writer for Test {} //~ ERROR cannot find trait `Writer` in this scope
@@ -21,7 +21,7 @@ mod foo {
 
     struct Test;
     impl Add for Test {} //~ ERROR cannot find trait `Add` in this scope
-    impl Clone for Test {} //~ ERROR cannot find trait `Clone` in this scope
+    impl Clone for Test {} //~ ERROR expected trait, found derive macro `Clone`
     impl Iterator for Test {} //~ ERROR cannot find trait `Iterator` in this scope
     impl ToString for Test {} //~ ERROR cannot find trait `ToString` in this scope
     impl Writer for Test {} //~ ERROR cannot find trait `Writer` in this scope
@@ -36,7 +36,7 @@ fn qux() {
     mod qux_inner {
         struct Test;
         impl Add for Test {} //~ ERROR cannot find trait `Add` in this scope
-        impl Clone for Test {} //~ ERROR cannot find trait `Clone` in this scope
+        impl Clone for Test {} //~ ERROR expected trait, found derive macro `Clone`
         impl Iterator for Test {} //~ ERROR cannot find trait `Iterator` in this scope
         impl ToString for Test {} //~ ERROR cannot find trait `ToString` in this scope
         impl Writer for Test {} //~ ERROR cannot find trait `Writer` in this scope

src/test/ui/no-implicit-prelude-nested.stderr

@@ -8,12 +8,12 @@ help: possible candidate is found in another module, you can import it into scop
 LL |         use std::ops::Add;
    |
 
-error[E0405]: cannot find trait `Clone` in this scope
+error[E0404]: expected trait, found derive macro `Clone`
   --> $DIR/no-implicit-prelude-nested.rs:12:14
    |
 LL |         impl Clone for Test {}
-   |              ^^^^^ not found in this scope
-help: possible candidates are found in other modules, you can import them into scope
+   |              ^^^^^ not a trait
+help: possible better candidates are found in other modules, you can import them into scope
    |
 LL |         use std::clone::Clone;
    |
@@ -72,12 +72,12 @@ help: possible candidate is found in another module, you can import it into scop
 LL |     use std::ops::Add;
    |
 
-error[E0405]: cannot find trait `Clone` in this scope
+error[E0404]: expected trait, found derive macro `Clone`
   --> $DIR/no-implicit-prelude-nested.rs:24:10
    |
 LL |     impl Clone for Test {}
-   |          ^^^^^ not found in this scope
-help: possible candidates are found in other modules, you can import them into scope
+   |          ^^^^^ not a trait
+help: possible better candidates are found in other modules, you can import them into scope
    |
 LL |     use std::clone::Clone;
    |
@@ -136,12 +136,12 @@ help: possible candidate is found in another module, you can import it into scop
 LL |         use std::ops::Add;
    |
 
-error[E0405]: cannot find trait `Clone` in this scope
+error[E0404]: expected trait, found derive macro `Clone`
   --> $DIR/no-implicit-prelude-nested.rs:39:14
    |
 LL |         impl Clone for Test {}
-   |              ^^^^^ not found in this scope
-help: possible candidates are found in other modules, you can import them into scope
+   |              ^^^^^ not a trait
+help: possible better candidates are found in other modules, you can import them into scope
    |
 LL |         use std::clone::Clone;
    |
@@ -192,5 +192,5 @@ LL |         use std::prelude::v1::drop;
 
 error: aborting due to 18 previous errors
 
-Some errors have detailed explanations: E0405, E0425.
-For more information about an error, try `rustc --explain E0405`.
+Some errors have detailed explanations: E0404, E0405, E0425.
+For more information about an error, try `rustc --explain E0404`.

src/test/ui/no-implicit-prelude.rs

@@ -8,7 +8,7 @@
 
 struct Test;
 impl Add for Test {} //~ ERROR cannot find trait `Add` in this scope
-impl Clone for Test {} //~ ERROR cannot find trait `Clone` in this scope
+impl Clone for Test {} //~ ERROR expected trait, found derive macro `Clone`
 impl Iterator for Test {} //~ ERROR cannot find trait `Iterator` in this scope
 impl ToString for Test {} //~ ERROR cannot find trait `ToString` in this scope
 impl Writer for Test {} //~ ERROR cannot find trait `Writer` in this scope

src/test/ui/no-implicit-prelude.stderr

@@ -8,12 +8,12 @@ help: possible candidate is found in another module, you can import it into scop
 LL | use std::ops::Add;
    |
 
-error[E0405]: cannot find trait `Clone` in this scope
+error[E0404]: expected trait, found derive macro `Clone`
   --> $DIR/no-implicit-prelude.rs:11:6
    |
 LL | impl Clone for Test {}
-   |      ^^^^^ not found in this scope
-help: possible candidates are found in other modules, you can import them into scope
+   |      ^^^^^ not a trait
+help: possible better candidates are found in other modules, you can import them into scope
    |
 LL | use std::clone::Clone;
    |
@@ -64,5 +64,5 @@ LL | use std::prelude::v1::drop;
 
 error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0405, E0425.
-For more information about an error, try `rustc --explain E0405`.
+Some errors have detailed explanations: E0404, E0405, E0425.
+For more information about an error, try `rustc --explain E0404`.

src/test/ui/proc-macro/derive-helper-shadowing.rs

@@ -19,7 +19,7 @@ struct S {
         struct U;
 
         mod inner {
-            #[empty_helper] //~ ERROR attribute `empty_helper` is currently unknown
+            #[empty_helper] //~ ERROR cannot find attribute macro `empty_helper` in this scope
             struct V;
         }
 

src/test/ui/proc-macro/derive-helper-shadowing.stderr

@@ -1,11 +1,8 @@
-error[E0658]: The attribute `empty_helper` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `empty_helper` in this scope
   --> $DIR/derive-helper-shadowing.rs:22:15
    |
 LL |             #[empty_helper]
    |               ^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error[E0659]: `empty_helper` is ambiguous (derive helper attribute vs any other name)
   --> $DIR/derive-helper-shadowing.rs:8:3
@@ -27,5 +24,4 @@ LL | use test_macros::empty_attr as empty_helper;
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0658, E0659.
-For more information about an error, try `rustc --explain E0658`.
+For more information about this error, try `rustc --explain E0659`.

src/test/ui/proc-macro/derive-still-gated.rs

@@ -3,7 +3,7 @@
 #[macro_use]
 extern crate test_macros;
 
-#[derive_Empty] //~ ERROR attribute `derive_Empty` is currently unknown
+#[derive_Empty] //~ ERROR cannot find attribute macro `derive_Empty` in this scope
 struct A;
 
 fn main() {}

src/test/ui/proc-macro/derive-still-gated.stderr

@@ -1,12 +1,8 @@
-error[E0658]: The attribute `derive_Empty` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `derive_Empty` in this scope
   --> $DIR/derive-still-gated.rs:6:3
    |
 LL | #[derive_Empty]
    |   ^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/proc-macro/expand-to-unstable-2.rs

@@ -1,11 +1,12 @@
 // aux-build:derive-unstable-2.rs
 
+#![feature(custom_attribute)]
+
 #[macro_use]
 extern crate derive_unstable_2;
 
 #[derive(Unstable)]
 //~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
-//~| ERROR attribute `rustc_foo` is currently unknown to the compiler
 
 struct A;
 

src/test/ui/proc-macro/expand-to-unstable-2.stderr

@@ -1,5 +1,5 @@
 error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
-  --> $DIR/expand-to-unstable-2.rs:6:10
+  --> $DIR/expand-to-unstable-2.rs:8:10
    |
 LL | #[derive(Unstable)]
    |          ^^^^^^^^
@@ -7,15 +7,6 @@ LL | #[derive(Unstable)]
    = note: for more information, see https://github.com/rust-lang/rust/issues/29642
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
 
-error[E0658]: The attribute `rustc_foo` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/expand-to-unstable-2.rs:6:10
-   |
-LL | #[derive(Unstable)]
-   |          ^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0658`.

src/test/ui/proc-macro/issue-41211.rs

@@ -3,11 +3,11 @@
 // FIXME: https://github.com/rust-lang/rust/issues/41430
 // This is a temporary regression test for the ICE reported in #41211
 
+#![feature(custom_attribute)]
 #![feature(custom_inner_attributes)]
 
 #![identity_attr]
-//~^ ERROR attribute `identity_attr` is currently unknown to the compiler
-//~| ERROR inconsistent resolution for a macro: first custom attribute, then attribute macro
+//~^ ERROR inconsistent resolution for a macro: first custom attribute, then attribute macro
 extern crate test_macros;
 use test_macros::identity_attr;
 

src/test/ui/proc-macro/issue-41211.stderr

@@ -1,18 +1,8 @@
-error[E0658]: The attribute `identity_attr` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/issue-41211.rs:8:4
-   |
-LL | #![identity_attr]
-   |    ^^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
-
 error: inconsistent resolution for a macro: first custom attribute, then attribute macro
-  --> $DIR/issue-41211.rs:8:4
+  --> $DIR/issue-41211.rs:9:4
    |
 LL | #![identity_attr]
    |    ^^^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/proc-macro/macro-namespace-reserved-2.rs

@@ -35,7 +35,7 @@ fn check_bang3() {
                        //~| ERROR expected macro, found derive macro `crate::MyTrait`
 }
 
-#[my_macro] //~ ERROR attribute `my_macro` is currently unknown
+#[my_macro] //~ ERROR cannot find attribute macro `my_macro` in this scope
 #[crate::my_macro] //~ ERROR can't use a procedural macro from the same crate that defines it
                    //~| ERROR expected attribute, found macro `crate::my_macro`
 fn check_attr1() {}

src/test/ui/proc-macro/macro-namespace-reserved-2.stderr

@@ -76,15 +76,6 @@ error: can't use a procedural macro from the same crate that defines it
 LL | #[derive(MyTrait)]
    |          ^^^^^^^
 
-error[E0658]: The attribute `my_macro` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/macro-namespace-reserved-2.rs:38:3
-   |
-LL | #[my_macro]
-   |   ^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
-
 error: can't use a procedural macro from the same crate that defines it
   --> $DIR/macro-namespace-reserved-2.rs:39:3
    |
@@ -97,6 +88,12 @@ error: expected attribute, found macro `crate::my_macro`
 LL | #[crate::my_macro]
    |   ^^^^^^^^^^^^^^^ not an attribute
 
+error: cannot find attribute macro `my_macro` in this scope
+  --> $DIR/macro-namespace-reserved-2.rs:38:3
+   |
+LL | #[my_macro]
+   |   ^^^^^^^^
+
 error: cannot find derive macro `my_macro` in this scope
   --> $DIR/macro-namespace-reserved-2.rs:48:10
    |
@@ -117,4 +114,3 @@ LL |     MyTrait!();
 
 error: aborting due to 19 previous errors
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/proc-macro/proc-macro-attributes.rs

@@ -4,7 +4,7 @@
 extern crate derive_b;
 
 #[B] //~ ERROR `B` is ambiguous
-#[C] //~ ERROR attribute `C` is currently unknown to the compiler
+#[C] //~ ERROR cannot find attribute macro `C` in this scope
 #[B(D)] //~ ERROR `B` is ambiguous
 #[B(E = "foo")] //~ ERROR `B` is ambiguous
 #[B(arbitrary tokens)] //~ ERROR `B` is ambiguous

src/test/ui/proc-macro/proc-macro-attributes.stderr

@@ -1,11 +1,8 @@
-error[E0658]: The attribute `C` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `C` in this scope
   --> $DIR/proc-macro-attributes.rs:7:3
    |
 LL | #[C]
-   |   ^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
+   |   ^ help: a derive helper attribute with a similar name exists: `B`
 
 error[E0659]: `B` is ambiguous (derive helper attribute vs any other name)
   --> $DIR/proc-macro-attributes.rs:6:3
@@ -77,5 +74,4 @@ LL | #[macro_use]
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0658, E0659.
-For more information about an error, try `rustc --explain E0658`.
+For more information about this error, try `rustc --explain E0659`.

src/test/ui/proc-macro/resolve-error.rs

@@ -24,11 +24,11 @@ macro_rules! attr_proc_mac {
 struct Foo;
 
 // Interpreted as a feature gated custom attribute
-#[attr_proc_macra] //~ ERROR attribute `attr_proc_macra` is currently unknown
+#[attr_proc_macra] //~ ERROR cannot find attribute macro `attr_proc_macra` in this scope
 struct Bar;
 
 // Interpreted as a feature gated custom attribute
-#[FooWithLongNan] //~ ERROR attribute `FooWithLongNan` is currently unknown
+#[FooWithLongNan] //~ ERROR cannot find attribute macro `FooWithLongNan` in this scope
 struct Asdf;
 
 #[derive(Dlone)]

src/test/ui/proc-macro/resolve-error.stderr

@@ -1,38 +1,32 @@
-error[E0658]: The attribute `attr_proc_macra` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/resolve-error.rs:27:3
-   |
-LL | #[attr_proc_macra]
-   |   ^^^^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
-
-error[E0658]: The attribute `FooWithLongNan` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/resolve-error.rs:31:3
-   |
-LL | #[FooWithLongNan]
-   |   ^^^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
-
 error: cannot find derive macro `FooWithLongNan` in this scope
   --> $DIR/resolve-error.rs:22:10
    |
 LL | #[derive(FooWithLongNan)]
-   |          ^^^^^^^^^^^^^^ help: try: `FooWithLongName`
+   |          ^^^^^^^^^^^^^^ help: a derive macro with a similar name exists: `FooWithLongName`
+
+error: cannot find attribute macro `attr_proc_macra` in this scope
+  --> $DIR/resolve-error.rs:27:3
+   |
+LL | #[attr_proc_macra]
+   |   ^^^^^^^^^^^^^^^ help: an attribute macro with a similar name exists: `attr_proc_macro`
+
+error: cannot find attribute macro `FooWithLongNan` in this scope
+  --> $DIR/resolve-error.rs:31:3
+   |
+LL | #[FooWithLongNan]
+   |   ^^^^^^^^^^^^^^
 
 error: cannot find derive macro `Dlone` in this scope
   --> $DIR/resolve-error.rs:34:10
    |
 LL | #[derive(Dlone)]
-   |          ^^^^^ help: try: `Clone`
+   |          ^^^^^ help: a derive macro with a similar name exists: `Clone`
 
 error: cannot find derive macro `Dlona` in this scope
   --> $DIR/resolve-error.rs:38:10
    |
 LL | #[derive(Dlona)]
-   |          ^^^^^ help: try: `Clona`
+   |          ^^^^^ help: a derive macro with a similar name exists: `Clona`
 
 error: cannot find derive macro `attr_proc_macra` in this scope
   --> $DIR/resolve-error.rs:42:10
@@ -44,13 +38,13 @@ error: cannot find macro `FooWithLongNama!` in this scope
   --> $DIR/resolve-error.rs:47:5
    |
 LL |     FooWithLongNama!();
-   |     ^^^^^^^^^^^^^^^ help: you could try the macro: `FooWithLongNam`
+   |     ^^^^^^^^^^^^^^^ help: a macro with a similar name exists: `FooWithLongNam`
 
 error: cannot find macro `attr_proc_macra!` in this scope
   --> $DIR/resolve-error.rs:50:5
    |
 LL |     attr_proc_macra!();
-   |     ^^^^^^^^^^^^^^^ help: you could try the macro: `attr_proc_mac`
+   |     ^^^^^^^^^^^^^^^ help: a macro with a similar name exists: `attr_proc_mac`
 
 error: cannot find macro `Dlona!` in this scope
   --> $DIR/resolve-error.rs:53:5
@@ -62,8 +56,7 @@ error: cannot find macro `bang_proc_macrp!` in this scope
   --> $DIR/resolve-error.rs:56:5
    |
 LL |     bang_proc_macrp!();
-   |     ^^^^^^^^^^^^^^^ help: you could try the macro: `bang_proc_macro`
+   |     ^^^^^^^^^^^^^^^ help: a macro with a similar name exists: `bang_proc_macro`
 
 error: aborting due to 10 previous errors
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/reserved/reserved-attr-on-macro.rs

@@ -1,5 +1,5 @@
 #[rustc_attribute_should_be_reserved]
-//~^ ERROR attribute `rustc_attribute_should_be_reserved` is currently unknown
+//~^ ERROR cannot find attribute macro `rustc_attribute_should_be_reserved` in this scope
 //~| ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
 
 macro_rules! foo {

src/test/ui/reserved/reserved-attr-on-macro.stderr

@@ -7,14 +7,11 @@ LL | #[rustc_attribute_should_be_reserved]
    = note: for more information, see https://github.com/rust-lang/rust/issues/29642
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
 
-error[E0658]: The attribute `rustc_attribute_should_be_reserved` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `rustc_attribute_should_be_reserved` in this scope
   --> $DIR/reserved-attr-on-macro.rs:1:3
    |
 LL | #[rustc_attribute_should_be_reserved]
    |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: cannot determine resolution for the macro `foo`
   --> $DIR/reserved-attr-on-macro.rs:10:5

src/test/ui/resolve/levenshtein.stderr

@@ -2,7 +2,7 @@ error[E0412]: cannot find type `esize` in this scope
   --> $DIR/levenshtein.rs:5:11
    |
 LL | fn foo(c: esize) {} // Misspelled primitive type name.
-   |           ^^^^^ help: a primitive type with a similar name exists: `isize`
+   |           ^^^^^ help: a builtin type with a similar name exists: `isize`
 
 error[E0412]: cannot find type `Baz` in this scope
   --> $DIR/levenshtein.rs:10:10

src/test/ui/span/issue-36530.rs

@@ -1,9 +1,10 @@
 // gate-test-custom_inner_attributes
 
-#[foo] //~ ERROR is currently unknown to the compiler
+#![feature(custom_attribute)]
+
+#[foo]
 mod foo {
-    #![foo] //~ ERROR is currently unknown to the compiler
-            //~| ERROR non-builtin inner attributes are unstable
+    #![foo] //~ ERROR non-builtin inner attributes are unstable
 }
 
 fn main() {}

src/test/ui/span/issue-36530.stderr

@@ -1,14 +1,5 @@
-error[E0658]: The attribute `foo` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/issue-36530.rs:3:3
-   |
-LL | #[foo]
-   |   ^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
-
 error[E0658]: non-builtin inner attributes are unstable
-  --> $DIR/issue-36530.rs:5:5
+  --> $DIR/issue-36530.rs:7:5
    |
 LL |     #![foo]
    |     ^^^^^^^
@@ -16,15 +7,6 @@ LL |     #![foo]
    = note: for more information, see https://github.com/rust-lang/rust/issues/54726
    = help: add `#![feature(custom_inner_attributes)]` to the crate attributes to enable
 
-error[E0658]: The attribute `foo` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/issue-36530.rs:5:8
-   |
-LL |     #![foo]
-   |        ^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
-
-error: aborting due to 3 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0658`.

src/test/ui/suggestions/attribute-typos.rs

@@ -1,11 +1,11 @@
-#[deprcated] //~ ERROR attribute `deprcated` is currently unknown
+#[deprcated] //~ ERROR cannot find attribute macro `deprcated` in this scope
 fn foo() {}
 
-#[tests] //~ ERROR attribute `tests` is currently unknown to the compiler
+#[tests] //~ ERROR cannot find attribute macro `tests` in this scope
 fn bar() {}
 
 #[rustc_err]
-//~^ ERROR attribute `rustc_err` is currently unknown
+//~^ ERROR cannot find attribute macro `rustc_err` in this scope
 //~| ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
 
 fn main() {}

src/test/ui/suggestions/attribute-typos.stderr

@@ -7,32 +7,23 @@ LL | #[rustc_err]
    = note: for more information, see https://github.com/rust-lang/rust/issues/29642
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
 
-error[E0658]: The attribute `rustc_err` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `rustc_err` in this scope
   --> $DIR/attribute-typos.rs:7:3
    |
 LL | #[rustc_err]
-   |   ^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
+   |   ^^^^^^^^^ help: a built-in attribute with a similar name exists: `rustc_error`
 
-error[E0658]: The attribute `tests` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `tests` in this scope
   --> $DIR/attribute-typos.rs:4:3
    |
 LL | #[tests]
-   |   ^^^^^ help: a built-in attribute with a similar name exists: `test`
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
+   |   ^^^^^ help: an attribute macro with a similar name exists: `test`
 
-error[E0658]: The attribute `deprcated` is currently unknown to the compiler and may have meaning added to it in the future
+error: cannot find attribute macro `deprcated` in this scope
   --> $DIR/attribute-typos.rs:1:3
    |
 LL | #[deprcated]
    |   ^^^^^^^^^ help: a built-in attribute with a similar name exists: `deprecated`
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
 
 error: aborting due to 4 previous errors
 

src/test/ui/tool-attributes/tool-attributes-misplaced-1.rs

@@ -5,7 +5,7 @@ type B = rustfmt::skip; //~ ERROR expected type, found tool attribute `rustfmt::
 struct S;
 
 // Interpreted as a feature gated custom attribute
-#[rustfmt] //~ ERROR attribute `rustfmt` is currently unknown
+#[rustfmt] //~ ERROR cannot find attribute macro `rustfmt` in this scope
 fn check() {}
 
 #[rustfmt::skip] // OK

src/test/ui/tool-attributes/tool-attributes-misplaced-1.stderr

@@ -1,18 +1,15 @@
-error[E0658]: The attribute `rustfmt` is currently unknown to the compiler and may have meaning added to it in the future
-  --> $DIR/tool-attributes-misplaced-1.rs:8:3
-   |
-LL | #[rustfmt]
-   |   ^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
-   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable
-
 error: cannot find derive macro `rustfmt` in this scope
   --> $DIR/tool-attributes-misplaced-1.rs:4:10
    |
 LL | #[derive(rustfmt)]
    |          ^^^^^^^
 
+error: cannot find attribute macro `rustfmt` in this scope
+  --> $DIR/tool-attributes-misplaced-1.rs:8:3
+   |
+LL | #[rustfmt]
+   |   ^^^^^^^
+
 error: cannot find macro `rustfmt!` in this scope
   --> $DIR/tool-attributes-misplaced-1.rs:14:5
    |
@@ -45,5 +42,4 @@ LL |     rustfmt::skip;
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0423, E0658.
-For more information about an error, try `rustc --explain E0423`.
+For more information about this error, try `rustc --explain E0423`.