Auto merge of #142432 - matthiaskrgr:rollup-ziuls9y, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - rust-lang/rust#138016 (Added `Clone` implementation for `ChunkBy`)
 - rust-lang/rust#141162 (refactor  `AttributeGate` and `rustc_attr!` to emit notes during feature checking)
 - rust-lang/rust#141474 (Add `ParseMode::Diagnostic` and fix multiline spans in diagnostic attribute lints)
 - rust-lang/rust#141947 (Specify that "option-like" enums must be `#[repr(Rust)]` to be ABI-compatible with their non-1ZST field.)
 - rust-lang/rust#142252 (Improve clarity of `core::sync::atomic` docs about "Considerations" in regards to CAS operations)
 - rust-lang/rust#142337 (miri: add flag to suppress float non-determinism)

r? `@ghost`
`@rustbot` modify labels: rollup

24 files changed, 339 insertions, 124 deletions

diff --git a/tests/ui/consts/gate-do-not-const-check.rs b/tests/ui/consts/gate-do-not-const-check.rs
index be7e70dfabb..0ebb1e7c82e 100644
--- a/tests/ui/consts/gate-do-not-const-check.rs
+++ b/tests/ui/consts/gate-do-not-const-check.rs
@@ -1,5 +1,7 @@
 #[rustc_do_not_const_check]
-//~^ ERROR this is an internal attribute that will never be stable
+//~^ ERROR use of an internal attribute [E0658]
+//~| NOTE the `#[rustc_do_not_const_check]` attribute is an internal implementation detail that will never be stable
+//~| NOTE `#[rustc_do_not_const_check]` skips const-check for this function's body
 const fn foo() {}
 
 fn main() {}
diff --git a/tests/ui/consts/gate-do-not-const-check.stderr b/tests/ui/consts/gate-do-not-const-check.stderr
index 74ea71c4ed8..778ee50e71b 100644
--- a/tests/ui/consts/gate-do-not-const-check.stderr
+++ b/tests/ui/consts/gate-do-not-const-check.stderr
@@ -1,11 +1,12 @@
-error[E0658]: this is an internal attribute that will never be stable
+error[E0658]: use of an internal attribute
   --> $DIR/gate-do-not-const-check.rs:1:1
    |
 LL | #[rustc_do_not_const_check]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_do_not_const_check]` attribute is an internal implementation detail that will never be stable
+   = note: `#[rustc_do_not_const_check]` skips const-check for this function's body
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/diagnostic_namespace/multiline_spans.rs b/tests/ui/diagnostic_namespace/multiline_spans.rs
new file mode 100644
index 00000000000..994dd9fd011
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/multiline_spans.rs
@@ -0,0 +1,55 @@
+#![crate_type = "lib"]
+#![deny(unknown_or_malformed_diagnostic_attributes)]
+
+
+#[diagnostic::on_unimplemented(message = "here is a big \
+                                         multiline string \
+                                         {unknown}")]
+//~^ ERROR there is no parameter `unknown` on trait `MultiLine` [unknown_or_malformed_diagnostic_attributes]
+pub trait MultiLine {}
+
+#[diagnostic::on_unimplemented(message = "here is a big \
+                                         multiline string {unknown}")]
+//~^ ERROR there is no parameter `unknown` on trait `MultiLine2` [unknown_or_malformed_diagnostic_attributes]
+pub trait MultiLine2 {}
+
+#[diagnostic::on_unimplemented(message = "here is a big \
+    multiline string {unknown}")]
+//~^ ERROR there is no parameter `unknown` on trait `MultiLine3` [unknown_or_malformed_diagnostic_attributes]
+pub trait MultiLine3 {}
+
+
+#[diagnostic::on_unimplemented(message = "here is a big \
+\
+                \
+                                \
+                                                \
+    multiline string {unknown}")]
+//~^ ERROR there is no parameter `unknown` on trait `MultiLine4` [unknown_or_malformed_diagnostic_attributes]
+pub trait MultiLine4 {}
+
+#[diagnostic::on_unimplemented(message = "here is a big \
+                                         multiline string \
+                                         {Self:+}")]
+//~^ ERROR invalid format specifier [unknown_or_malformed_diagnostic_attributes]
+pub trait MultiLineFmt {}
+
+#[diagnostic::on_unimplemented(message = "here is a big \
+                                         multiline string {Self:X}")]
+//~^ ERROR invalid format specifier [unknown_or_malformed_diagnostic_attributes]
+pub trait MultiLineFmt2 {}
+
+#[diagnostic::on_unimplemented(message = "here is a big \
+    multiline string {Self:#}")]
+//~^ ERROR invalid format specifier [unknown_or_malformed_diagnostic_attributes]
+pub trait MultiLineFmt3 {}
+
+
+#[diagnostic::on_unimplemented(message = "here is a big \
+\
+                \
+                                \
+                                                \
+    multiline string {Self:?}")]
+//~^ ERROR invalid format specifier [unknown_or_malformed_diagnostic_attributes]
+pub trait MultiLineFmt4 {}
diff --git a/tests/ui/diagnostic_namespace/multiline_spans.stderr b/tests/ui/diagnostic_namespace/multiline_spans.stderr
new file mode 100644
index 00000000000..894bfe3d90a
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/multiline_spans.stderr
@@ -0,0 +1,71 @@
+error: there is no parameter `unknown` on trait `MultiLine`
+  --> $DIR/multiline_spans.rs:7:43
+   |
+LL | ...                   {unknown}")]
+   |                        ^^^^^^^
+   |
+   = help: expect either a generic argument name or `{Self}` as format argument
+note: the lint level is defined here
+  --> $DIR/multiline_spans.rs:2:9
+   |
+LL | #![deny(unknown_or_malformed_diagnostic_attributes)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: there is no parameter `unknown` on trait `MultiLine2`
+  --> $DIR/multiline_spans.rs:12:60
+   |
+LL | ...                   multiline string {unknown}")]
+   |                                         ^^^^^^^
+   |
+   = help: expect either a generic argument name or `{Self}` as format argument
+
+error: there is no parameter `unknown` on trait `MultiLine3`
+  --> $DIR/multiline_spans.rs:17:23
+   |
+LL |     multiline string {unknown}")]
+   |                       ^^^^^^^
+   |
+   = help: expect either a generic argument name or `{Self}` as format argument
+
+error: there is no parameter `unknown` on trait `MultiLine4`
+  --> $DIR/multiline_spans.rs:27:23
+   |
+LL |     multiline string {unknown}")]
+   |                       ^^^^^^^
+   |
+   = help: expect either a generic argument name or `{Self}` as format argument
+
+error: invalid format specifier
+  --> $DIR/multiline_spans.rs:33:47
+   |
+LL | ...                   {Self:+}")]
+   |                            ^^
+   |
+   = help: no format specifier are supported in this position
+
+error: invalid format specifier
+  --> $DIR/multiline_spans.rs:38:64
+   |
+LL | ...                   multiline string {Self:X}")]
+   |                                             ^^
+   |
+   = help: no format specifier are supported in this position
+
+error: invalid format specifier
+  --> $DIR/multiline_spans.rs:43:27
+   |
+LL |     multiline string {Self:#}")]
+   |                           ^^
+   |
+   = help: no format specifier are supported in this position
+
+error: invalid format specifier
+  --> $DIR/multiline_spans.rs:53:27
+   |
+LL |     multiline string {Self:?}")]
+   |                           ^^
+   |
+   = help: no format specifier are supported in this position
+
+error: aborting due to 8 previous errors
+
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/broken_format.rs b/tests/ui/diagnostic_namespace/on_unimplemented/broken_format.rs
index 44f269eb967..4762d9e793f 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/broken_format.rs
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/broken_format.rs
@@ -12,6 +12,8 @@ trait ImportantTrait2 {}
 #[diagnostic::on_unimplemented(message = "Test {1:}")]
 //~^WARN positional format arguments are not allowed here
 //~|WARN positional format arguments are not allowed here
+//~|WARN invalid format specifier [unknown_or_malformed_diagnostic_attributes]
+//~|WARN invalid format specifier [unknown_or_malformed_diagnostic_attributes]
 trait ImportantTrait3 {}
 
 #[diagnostic::on_unimplemented(message = "Test {Self:123}")]
@@ -20,17 +22,22 @@ trait ImportantTrait3 {}
 trait ImportantTrait4 {}
 
 #[diagnostic::on_unimplemented(message = "Test {Self:!}")]
-//~^WARN expected `}`, found `!`
-//~|WARN expected `}`, found `!`
-//~|WARN unmatched `}` found
-//~|WARN unmatched `}` found
+//~^WARN invalid format specifier [unknown_or_malformed_diagnostic_attributes]
+//~|WARN invalid format specifier [unknown_or_malformed_diagnostic_attributes]
 trait ImportantTrait5 {}
 
+#[diagnostic::on_unimplemented(message = "Test {Self:}")]
+//~^WARN invalid format specifier [unknown_or_malformed_diagnostic_attributes]
+//~|WARN invalid format specifier [unknown_or_malformed_diagnostic_attributes]
+trait ImportantTrait6 {}
+
+
 fn check_1(_: impl ImportantTrait1) {}
 fn check_2(_: impl ImportantTrait2) {}
 fn check_3(_: impl ImportantTrait3) {}
 fn check_4(_: impl ImportantTrait4) {}
 fn check_5(_: impl ImportantTrait5) {}
+fn check_6(_: impl ImportantTrait6) {}
 
 fn main() {
     check_1(());
@@ -42,5 +49,7 @@ fn main() {
     check_4(());
     //~^ERROR Test ()
     check_5(());
-    //~^ERROR Test {Self:!}
+    //~^ERROR Test ()
+    check_6(());
+    //~^ERROR Test ()
 }
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/broken_format.stderr b/tests/ui/diagnostic_namespace/on_unimplemented/broken_format.stderr
index a82a1e78da0..2670d0630f7 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/broken_format.stderr
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/broken_format.stderr
@@ -14,6 +14,14 @@ LL | #[diagnostic::on_unimplemented(message = "Test {}")]
    |
    = help: only named format arguments with the name of one of the generic types are allowed in this context
 
+warning: invalid format specifier
+  --> $DIR/broken_format.rs:12:50
+   |
+LL | #[diagnostic::on_unimplemented(message = "Test {1:}")]
+   |                                                  ^
+   |
+   = help: no format specifier are supported in this position
+
 warning: positional format arguments are not allowed here
   --> $DIR/broken_format.rs:12:49
    |
@@ -23,24 +31,28 @@ LL | #[diagnostic::on_unimplemented(message = "Test {1:}")]
    = help: only named format arguments with the name of one of the generic types are allowed in this context
 
 warning: invalid format specifier
-  --> $DIR/broken_format.rs:17:42
+  --> $DIR/broken_format.rs:19:53
    |
 LL | #[diagnostic::on_unimplemented(message = "Test {Self:123}")]
-   |                                          ^^^^^^^^^^^^^^^^^
+   |                                                     ^^^^
    |
    = help: no format specifier are supported in this position
 
-warning: expected `}`, found `!`
-  --> $DIR/broken_format.rs:22:42
+warning: invalid format specifier
+  --> $DIR/broken_format.rs:24:53
    |
 LL | #[diagnostic::on_unimplemented(message = "Test {Self:!}")]
-   |                                          ^^^^^^^^^^^^^^^
+   |                                                     ^^
+   |
+   = help: no format specifier are supported in this position
 
-warning: unmatched `}` found
-  --> $DIR/broken_format.rs:22:42
+warning: invalid format specifier
+  --> $DIR/broken_format.rs:29:53
    |
-LL | #[diagnostic::on_unimplemented(message = "Test {Self:!}")]
-   |                                          ^^^^^^^^^^^^^^^
+LL | #[diagnostic::on_unimplemented(message = "Test {Self:}")]
+   |                                                     ^
+   |
+   = help: no format specifier are supported in this position
 
 warning: unmatched `}` found
   --> $DIR/broken_format.rs:2:42
@@ -51,7 +63,7 @@ LL | #[diagnostic::on_unimplemented(message = "{{Test } thing")]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: {{Test } thing
-  --> $DIR/broken_format.rs:36:13
+  --> $DIR/broken_format.rs:43:13
    |
 LL |     check_1(());
    |     ------- ^^ the trait `ImportantTrait1` is not implemented for `()`
@@ -64,7 +76,7 @@ help: this trait has no implementations, consider adding one
 LL | trait ImportantTrait1 {}
    | ^^^^^^^^^^^^^^^^^^^^^
 note: required by a bound in `check_1`
-  --> $DIR/broken_format.rs:29:20
+  --> $DIR/broken_format.rs:35:20
    |
 LL | fn check_1(_: impl ImportantTrait1) {}
    |                    ^^^^^^^^^^^^^^^ required by this bound in `check_1`
@@ -79,7 +91,7 @@ LL | #[diagnostic::on_unimplemented(message = "Test {}")]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: Test {}
-  --> $DIR/broken_format.rs:38:13
+  --> $DIR/broken_format.rs:45:13
    |
 LL |     check_2(());
    |     ------- ^^ the trait `ImportantTrait2` is not implemented for `()`
@@ -92,11 +104,20 @@ help: this trait has no implementations, consider adding one
 LL | trait ImportantTrait2 {}
    | ^^^^^^^^^^^^^^^^^^^^^
 note: required by a bound in `check_2`
-  --> $DIR/broken_format.rs:30:20
+  --> $DIR/broken_format.rs:36:20
    |
 LL | fn check_2(_: impl ImportantTrait2) {}
    |                    ^^^^^^^^^^^^^^^ required by this bound in `check_2`
 
+warning: invalid format specifier
+  --> $DIR/broken_format.rs:12:50
+   |
+LL | #[diagnostic::on_unimplemented(message = "Test {1:}")]
+   |                                                  ^
+   |
+   = help: no format specifier are supported in this position
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
 warning: positional format arguments are not allowed here
   --> $DIR/broken_format.rs:12:49
    |
@@ -107,7 +128,7 @@ LL | #[diagnostic::on_unimplemented(message = "Test {1:}")]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: Test {1}
-  --> $DIR/broken_format.rs:40:13
+  --> $DIR/broken_format.rs:47:13
    |
 LL |     check_3(());
    |     ------- ^^ the trait `ImportantTrait3` is not implemented for `()`
@@ -115,27 +136,27 @@ LL |     check_3(());
    |     required by a bound introduced by this call
    |
 help: this trait has no implementations, consider adding one
-  --> $DIR/broken_format.rs:15:1
+  --> $DIR/broken_format.rs:17:1
    |
 LL | trait ImportantTrait3 {}
    | ^^^^^^^^^^^^^^^^^^^^^
 note: required by a bound in `check_3`
-  --> $DIR/broken_format.rs:31:20
+  --> $DIR/broken_format.rs:37:20
    |
 LL | fn check_3(_: impl ImportantTrait3) {}
    |                    ^^^^^^^^^^^^^^^ required by this bound in `check_3`
 
 warning: invalid format specifier
-  --> $DIR/broken_format.rs:17:42
+  --> $DIR/broken_format.rs:19:53
    |
 LL | #[diagnostic::on_unimplemented(message = "Test {Self:123}")]
-   |                                          ^^^^^^^^^^^^^^^^^
+   |                                                     ^^^^
    |
    = help: no format specifier are supported in this position
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: Test ()
-  --> $DIR/broken_format.rs:42:13
+  --> $DIR/broken_format.rs:49:13
    |
 LL |     check_4(());
    |     ------- ^^ the trait `ImportantTrait4` is not implemented for `()`
@@ -143,34 +164,27 @@ LL |     check_4(());
    |     required by a bound introduced by this call
    |
 help: this trait has no implementations, consider adding one
-  --> $DIR/broken_format.rs:20:1
+  --> $DIR/broken_format.rs:22:1
    |
 LL | trait ImportantTrait4 {}
    | ^^^^^^^^^^^^^^^^^^^^^
 note: required by a bound in `check_4`
-  --> $DIR/broken_format.rs:32:20
+  --> $DIR/broken_format.rs:38:20
    |
 LL | fn check_4(_: impl ImportantTrait4) {}
    |                    ^^^^^^^^^^^^^^^ required by this bound in `check_4`
 
-warning: expected `}`, found `!`
-  --> $DIR/broken_format.rs:22:42
-   |
-LL | #[diagnostic::on_unimplemented(message = "Test {Self:!}")]
-   |                                          ^^^^^^^^^^^^^^^
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-warning: unmatched `}` found
-  --> $DIR/broken_format.rs:22:42
+warning: invalid format specifier
+  --> $DIR/broken_format.rs:24:53
    |
 LL | #[diagnostic::on_unimplemented(message = "Test {Self:!}")]
-   |                                          ^^^^^^^^^^^^^^^
+   |                                                     ^^
    |
+   = help: no format specifier are supported in this position
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error[E0277]: Test {Self:!}
-  --> $DIR/broken_format.rs:44:13
+error[E0277]: Test ()
+  --> $DIR/broken_format.rs:51:13
    |
 LL |     check_5(());
    |     ------- ^^ the trait `ImportantTrait5` is not implemented for `()`
@@ -183,11 +197,39 @@ help: this trait has no implementations, consider adding one
 LL | trait ImportantTrait5 {}
    | ^^^^^^^^^^^^^^^^^^^^^
 note: required by a bound in `check_5`
-  --> $DIR/broken_format.rs:33:20
+  --> $DIR/broken_format.rs:39:20
    |
 LL | fn check_5(_: impl ImportantTrait5) {}
    |                    ^^^^^^^^^^^^^^^ required by this bound in `check_5`
 
-error: aborting due to 5 previous errors; 12 warnings emitted
+warning: invalid format specifier
+  --> $DIR/broken_format.rs:29:53
+   |
+LL | #[diagnostic::on_unimplemented(message = "Test {Self:}")]
+   |                                                     ^
+   |
+   = help: no format specifier are supported in this position
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0277]: Test ()
+  --> $DIR/broken_format.rs:53:13
+   |
+LL |     check_6(());
+   |     ------- ^^ the trait `ImportantTrait6` is not implemented for `()`
+   |     |
+   |     required by a bound introduced by this call
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/broken_format.rs:32:1
+   |
+LL | trait ImportantTrait6 {}
+   | ^^^^^^^^^^^^^^^^^^^^^
+note: required by a bound in `check_6`
+  --> $DIR/broken_format.rs:40:20
+   |
+LL | fn check_6(_: impl ImportantTrait6) {}
+   |                    ^^^^^^^^^^^^^^^ required by this bound in `check_6`
+
+error: aborting due to 6 previous errors; 14 warnings emitted
 
 For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/feature-gates/feature-gate-pattern-complexity-limit.rs b/tests/ui/feature-gates/feature-gate-pattern-complexity-limit.rs
index d1f6f4755f0..ffb444cd9aa 100644
--- a/tests/ui/feature-gates/feature-gate-pattern-complexity-limit.rs
+++ b/tests/ui/feature-gates/feature-gate-pattern-complexity-limit.rs
@@ -1,6 +1,8 @@
 // check that `pattern_complexity_limit` is feature-gated
 
 #![pattern_complexity_limit = "42"]
-//~^ ERROR: the `#[pattern_complexity_limit]` attribute is just used for rustc unit tests
+//~^ ERROR: use of an internal attribute [E0658]
+//~| NOTE the `#[pattern_complexity_limit]` attribute is an internal implementation detail that will never be stable
+//~| NOTE: the `#[pattern_complexity_limit]` attribute is used for rustc unit tests
 
 fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-pattern-complexity-limit.stderr b/tests/ui/feature-gates/feature-gate-pattern-complexity-limit.stderr
index e6f17710e09..9ddea866ea9 100644
--- a/tests/ui/feature-gates/feature-gate-pattern-complexity-limit.stderr
+++ b/tests/ui/feature-gates/feature-gate-pattern-complexity-limit.stderr
@@ -1,11 +1,12 @@
-error[E0658]: the `#[pattern_complexity_limit]` attribute is just used for rustc unit tests and will never be stable
+error[E0658]: use of an internal attribute
   --> $DIR/feature-gate-pattern-complexity-limit.rs:3:1
    |
 LL | #![pattern_complexity_limit = "42"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[pattern_complexity_limit]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[pattern_complexity_limit]` attribute is used for rustc unit tests
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs
index 025b4b52f12..17556723622 100644
--- a/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs
+++ b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs
@@ -1,6 +1,12 @@
 // Test that `#[rustc_*]` attributes are gated by `rustc_attrs` feature gate.
 
-#[rustc_variance] //~ ERROR the `#[rustc_variance]` attribute is just used for rustc unit tests and will never be stable
-#[rustc_nonnull_optimization_guaranteed] //~ ERROR the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to document guaranteed niche optimizations in libcore and libstd and will never be stable
-
+#[rustc_variance]
+//~^ ERROR use of an internal attribute [E0658]
+//~| NOTE the `#[rustc_variance]` attribute is an internal implementation detail that will never be stable
+//~| NOTE the `#[rustc_variance]` attribute is used for rustc unit tests
+#[rustc_nonnull_optimization_guaranteed]
+//~^ ERROR use of an internal attribute [E0658]
+//~| NOTE the `#[rustc_nonnull_optimization_guaranteed]` attribute is an internal implementation detail that will never be stable
+//~| NOTE  the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to document guaranteed niche optimizations in the standard library
+//~| NOTE the compiler does not even check whether the type indeed is being non-null-optimized; it is your responsibility to ensure that the attribute is only used on types that are optimized
 fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr
index 0f760e0602d..159d383e408 100644
--- a/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr
+++ b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr
@@ -1,21 +1,23 @@
-error[E0658]: the `#[rustc_variance]` attribute is just used for rustc unit tests and will never be stable
+error[E0658]: use of an internal attribute
   --> $DIR/feature-gate-rustc-attrs-1.rs:3:1
    |
 LL | #[rustc_variance]
    | ^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_variance]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[rustc_variance]` attribute is used for rustc unit tests
 
-error[E0658]: the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to document guaranteed niche optimizations in libcore and libstd and will never be stable
-              (note that the compiler does not even check whether the type indeed is being non-null-optimized; it is your responsibility to ensure that the attribute is only used on types that are optimized)
-  --> $DIR/feature-gate-rustc-attrs-1.rs:4:1
+error[E0658]: use of an internal attribute
+  --> $DIR/feature-gate-rustc-attrs-1.rs:7:1
    |
 LL | #[rustc_nonnull_optimization_guaranteed]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_nonnull_optimization_guaranteed]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to document guaranteed niche optimizations in the standard library
+   = note: the compiler does not even check whether the type indeed is being non-null-optimized; it is your responsibility to ensure that the attribute is only used on types that are optimized
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/feature-gates/feature-gate-rustc-attrs.rs b/tests/ui/feature-gates/feature-gate-rustc-attrs.rs
index c985298a30a..e7b2eca6f85 100644
--- a/tests/ui/feature-gates/feature-gate-rustc-attrs.rs
+++ b/tests/ui/feature-gates/feature-gate-rustc-attrs.rs
@@ -8,15 +8,19 @@ mod unknown { pub macro rustc() {} }
 #[rustc::unknown]
 //~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
 //~| ERROR expected attribute, found macro `rustc::unknown`
+//~| NOTE not an attribute
 fn f() {}
 
 #[unknown::rustc]
 //~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
 //~| ERROR expected attribute, found macro `unknown::rustc`
+//~| NOTE not an attribute
 fn g() {}
 
 #[rustc_dummy]
-//~^ ERROR the `#[rustc_dummy]` attribute is just used for rustc unit tests
+//~^ ERROR use of an internal attribute [E0658]
+//~| NOTE the `#[rustc_dummy]` attribute is an internal implementation detail that will never be stable
+//~| NOTE the `#[rustc_dummy]` attribute is used for rustc unit tests
 #[rustc_unknown]
 //~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
 //~| ERROR cannot find attribute `rustc_unknown` in this scope
diff --git a/tests/ui/feature-gates/feature-gate-rustc-attrs.stderr b/tests/ui/feature-gates/feature-gate-rustc-attrs.stderr
index c7a5ef3e44b..d58603883f1 100644
--- a/tests/ui/feature-gates/feature-gate-rustc-attrs.stderr
+++ b/tests/ui/feature-gates/feature-gate-rustc-attrs.stderr
@@ -11,37 +11,38 @@ LL | #[rustc::unknown]
    |   ^^^^^^^^^^^^^^ not an attribute
 
 error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
-  --> $DIR/feature-gate-rustc-attrs.rs:13:12
+  --> $DIR/feature-gate-rustc-attrs.rs:14:12
    |
 LL | #[unknown::rustc]
    |            ^^^^^
 
 error: expected attribute, found macro `unknown::rustc`
-  --> $DIR/feature-gate-rustc-attrs.rs:13:3
+  --> $DIR/feature-gate-rustc-attrs.rs:14:3
    |
 LL | #[unknown::rustc]
    |   ^^^^^^^^^^^^^^ not an attribute
 
 error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
-  --> $DIR/feature-gate-rustc-attrs.rs:20:3
+  --> $DIR/feature-gate-rustc-attrs.rs:24:3
    |
 LL | #[rustc_unknown]
    |   ^^^^^^^^^^^^^
 
 error: cannot find attribute `rustc_unknown` in this scope
-  --> $DIR/feature-gate-rustc-attrs.rs:20:3
+  --> $DIR/feature-gate-rustc-attrs.rs:24:3
    |
 LL | #[rustc_unknown]
    |   ^^^^^^^^^^^^^
 
-error[E0658]: the `#[rustc_dummy]` attribute is just used for rustc unit tests and will never be stable
-  --> $DIR/feature-gate-rustc-attrs.rs:18:1
+error[E0658]: use of an internal attribute
+  --> $DIR/feature-gate-rustc-attrs.rs:20:1
    |
 LL | #[rustc_dummy]
    | ^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_dummy]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[rustc_dummy]` attribute is used for rustc unit tests
 
 error: aborting due to 7 previous errors
 
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.rs b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.rs
index 02a56c7e6aa..7fb11b7bde7 100644
--- a/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.rs
+++ b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.rs
@@ -11,9 +11,11 @@
 
 #![macro_export]
 //~^ ERROR: `macro_export` attribute cannot be used at crate level
-#![rustc_main] //~ ERROR: the `#[rustc_main]` attribute is used internally to specify
+#![rustc_main]
 //~^ ERROR: `rustc_main` attribute cannot be used at crate level
-//~| NOTE: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+//~| ERROR: use of an internal attribute [E0658]
+//~| NOTE: the `#[rustc_main]` attribute is an internal implementation detail that will never be stable
+//~| NOTE: the `#[rustc_main]` attribute is used internally to specify test entry point function
 #![repr()]
 //~^ ERROR: `repr` attribute cannot be used at crate level
 #![path = "3800"]
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr
index 5c2a3ae699c..bdca6163473 100644
--- a/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr
+++ b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr
@@ -1,14 +1,15 @@
-error[E0658]: the `#[rustc_main]` attribute is used internally to specify test entry point function
+error[E0658]: use of an internal attribute
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:14:1
    |
 LL | #![rustc_main]
    | ^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_main]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[rustc_main]` attribute is used internally to specify test entry point function
 
 error: valid forms for the attribute are `#[inline]` and `#[inline(always|never)]`
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:44:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:46:5
    |
 LL |     #[inline = "2100"] fn f() { }
    |     ^^^^^^^^^^^^^^^^^^
@@ -18,7 +19,7 @@ LL |     #[inline = "2100"] fn f() { }
    = note: `#[deny(ill_formed_attribute_input)]` on by default
 
 error[E0518]: attribute should be applied to function or closure
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:30:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:32:1
    |
 LL |   #[inline]
    |   ^^^^^^^^^
@@ -29,7 +30,7 @@ LL | | }
    | |_- not a function or closure
 
 error: attribute should be applied to an `extern crate` item
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:63:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:65:1
    |
 LL |   #[no_link]
    |   ^^^^^^^^^^
@@ -43,7 +44,7 @@ LL | | }
    | |_- not an `extern crate` item
 
 error: attribute should be applied to a free function, impl method or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:89:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:91:1
    |
 LL |   #[export_name = "2200"]
    |   ^^^^^^^^^^^^^^^^^^^^^^^
@@ -57,7 +58,7 @@ LL | | }
    | |_- not a free function, impl method or static
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:123:8
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:125:8
    |
 LL |   #[repr(C)]
    |          ^
@@ -70,7 +71,7 @@ LL | | }
    | |_- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:147:8
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:149:8
    |
 LL |   #[repr(Rust)]
    |          ^^^^
@@ -83,19 +84,19 @@ LL | | }
    | |_- not a struct, enum, or union
 
 error: attribute should be applied to an `extern crate` item
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:24:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:26:1
    |
 LL | #![no_link]
    | ^^^^^^^^^^^ not an `extern crate` item
 
 error: attribute should be applied to a free function, impl method or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:26:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:28:1
    |
 LL | #![export_name = "2200"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^ not a free function, impl method or static
 
 error[E0518]: attribute should be applied to function or closure
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:28:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:30:1
    |
 LL | #![inline]
    | ^^^^^^^^^^ not a function or closure
@@ -131,7 +132,7 @@ LL + #[rustc_main]
    |
 
 error: `path` attribute cannot be used at crate level
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:19:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:21:1
    |
 LL | #![path = "3800"]
    | ^^^^^^^^^^^^^^^^^
@@ -146,7 +147,7 @@ LL + #[path = "3800"]
    |
 
 error: `automatically_derived` attribute cannot be used at crate level
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:21:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:23:1
    |
 LL | #![automatically_derived]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -161,7 +162,7 @@ LL + #[automatically_derived]
    |
 
 error: `repr` attribute cannot be used at crate level
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:17:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:19:1
    |
 LL | #![repr()]
    | ^^^^^^^^^^
@@ -176,139 +177,139 @@ LL + #[repr()]
    |
 
 error[E0518]: attribute should be applied to function or closure
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:40:17
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:42:17
    |
 LL |     mod inner { #![inline] }
    |     ------------^^^^^^^^^^-- not a function or closure
 
 error[E0518]: attribute should be applied to function or closure
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:50:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:52:5
    |
 LL |     #[inline] struct S;
    |     ^^^^^^^^^ --------- not a function or closure
 
 error[E0518]: attribute should be applied to function or closure
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:54:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:56:5
    |
 LL |     #[inline] type T = S;
    |     ^^^^^^^^^ ----------- not a function or closure
 
 error[E0518]: attribute should be applied to function or closure
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:58:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:60:5
    |
 LL |     #[inline] impl S { }
    |     ^^^^^^^^^ ---------- not a function or closure
 
 error: attribute should be applied to an `extern crate` item
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:68:17
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:70:17
    |
 LL |     mod inner { #![no_link] }
    |     ------------^^^^^^^^^^^-- not an `extern crate` item
 
 error: attribute should be applied to an `extern crate` item
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:72:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:74:5
    |
 LL |     #[no_link] fn f() { }
    |     ^^^^^^^^^^ ---------- not an `extern crate` item
 
 error: attribute should be applied to an `extern crate` item
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:76:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:78:5
    |
 LL |     #[no_link] struct S;
    |     ^^^^^^^^^^ --------- not an `extern crate` item
 
 error: attribute should be applied to an `extern crate` item
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:80:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:82:5
    |
 LL |     #[no_link]type T = S;
    |     ^^^^^^^^^^----------- not an `extern crate` item
 
 error: attribute should be applied to an `extern crate` item
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:84:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:86:5
    |
 LL |     #[no_link] impl S { }
    |     ^^^^^^^^^^ ---------- not an `extern crate` item
 
 error: attribute should be applied to a free function, impl method or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:94:17
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:96:17
    |
 LL |     mod inner { #![export_name="2200"] }
    |     ------------^^^^^^^^^^^^^^^^^^^^^^-- not a free function, impl method or static
 
 error: attribute should be applied to a free function, impl method or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:100:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:102:5
    |
 LL |     #[export_name = "2200"] struct S;
    |     ^^^^^^^^^^^^^^^^^^^^^^^ --------- not a free function, impl method or static
 
 error: attribute should be applied to a free function, impl method or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:104:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:106:5
    |
 LL |     #[export_name = "2200"] type T = S;
    |     ^^^^^^^^^^^^^^^^^^^^^^^ ----------- not a free function, impl method or static
 
 error: attribute should be applied to a free function, impl method or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:108:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:110:5
    |
 LL |     #[export_name = "2200"] impl S { }
    |     ^^^^^^^^^^^^^^^^^^^^^^^ ---------- not a free function, impl method or static
 
 error: attribute should be applied to a free function, impl method or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:113:9
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:115:9
    |
 LL |         #[export_name = "2200"] fn foo();
    |         ^^^^^^^^^^^^^^^^^^^^^^^ --------- not a free function, impl method or static
 
 error: attribute should be applied to a free function, impl method or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:117:9
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:119:9
    |
 LL |         #[export_name = "2200"] fn bar() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^ ----------- not a free function, impl method or static
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:127:25
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:129:25
    |
 LL |     mod inner { #![repr(C)] }
    |     --------------------^---- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:131:12
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:133:12
    |
 LL |     #[repr(C)] fn f() { }
    |            ^   ---------- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:137:12
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:139:12
    |
 LL |     #[repr(C)] type T = S;
    |            ^   ----------- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:141:12
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:143:12
    |
 LL |     #[repr(C)] impl S { }
    |            ^   ---------- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:151:25
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:153:25
    |
 LL |     mod inner { #![repr(Rust)] }
    |     --------------------^^^^---- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:155:12
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:157:12
    |
 LL |     #[repr(Rust)] fn f() { }
    |            ^^^^   ---------- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:161:12
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:163:12
    |
 LL |     #[repr(Rust)] type T = S;
    |            ^^^^   ----------- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:165:12
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:167:12
    |
 LL |     #[repr(Rust)] impl S { }
    |            ^^^^   ---------- not a struct, enum, or union
diff --git a/tests/ui/force-inlining/gate.rs b/tests/ui/force-inlining/gate.rs
index cea094c14f2..5918b0d4979 100644
--- a/tests/ui/force-inlining/gate.rs
+++ b/tests/ui/force-inlining/gate.rs
@@ -2,11 +2,15 @@
 #![allow(internal_features)]
 
 #[rustc_force_inline]
-//~^ ERROR #[rustc_force_inline] forces a free function to be inlined
+//~^ ERROR use of an internal attribute [E0658]
+//~| NOTE the `#[rustc_force_inline]` attribute is an internal implementation detail that will never be stable
+//~| NOTE `#[rustc_force_inline]` forces a free function to be inlined
 pub fn bare() {
 }
 
 #[rustc_force_inline = "the test requires it"]
-//~^ ERROR #[rustc_force_inline] forces a free function to be inlined
+//~^ ERROR use of an internal attribute [E0658]
+//~| NOTE the `#[rustc_force_inline]` attribute is an internal implementation detail that will never be stable
+//~| NOTE `#[rustc_force_inline]` forces a free function to be inlined
 pub fn justified() {
 }
diff --git a/tests/ui/force-inlining/gate.stderr b/tests/ui/force-inlining/gate.stderr
index 964d43fa18f..6c2df08b1a3 100644
--- a/tests/ui/force-inlining/gate.stderr
+++ b/tests/ui/force-inlining/gate.stderr
@@ -1,20 +1,22 @@
-error[E0658]: #[rustc_force_inline] forces a free function to be inlined
+error[E0658]: use of an internal attribute
   --> $DIR/gate.rs:4:1
    |
 LL | #[rustc_force_inline]
    | ^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_force_inline]` attribute is an internal implementation detail that will never be stable
+   = note: `#[rustc_force_inline]` forces a free function to be inlined
 
-error[E0658]: #[rustc_force_inline] forces a free function to be inlined
-  --> $DIR/gate.rs:9:1
+error[E0658]: use of an internal attribute
+  --> $DIR/gate.rs:11:1
    |
 LL | #[rustc_force_inline = "the test requires it"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_force_inline]` attribute is an internal implementation detail that will never be stable
+   = note: `#[rustc_force_inline]` forces a free function to be inlined
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/on-unimplemented/feature-gate-on-unimplemented.rs b/tests/ui/on-unimplemented/feature-gate-on-unimplemented.rs
index 3cc50e3499a..436caab5d64 100644
--- a/tests/ui/on-unimplemented/feature-gate-on-unimplemented.rs
+++ b/tests/ui/on-unimplemented/feature-gate-on-unimplemented.rs
@@ -1,8 +1,9 @@
 // Test that `#[rustc_on_unimplemented]` is gated by `rustc_attrs` feature gate.
 
 #[rustc_on_unimplemented = "test error `{Self}` with `{Bar}`"]
-//~^ ERROR this is an internal attribute that will never be stable
-trait Foo<Bar>
-{}
+//~^ ERROR use of an internal attribute [E0658]
+//~| NOTE the `#[rustc_on_unimplemented]` attribute is an internal implementation detail that will never be stable
+//~| NOTE see `#[diagnostic::on_unimplemented]` for the stable equivalent of this attribute
+trait Foo<Bar> {}
 
 fn main() {}
diff --git a/tests/ui/on-unimplemented/feature-gate-on-unimplemented.stderr b/tests/ui/on-unimplemented/feature-gate-on-unimplemented.stderr
index 2733f7478f0..d1983088af8 100644
--- a/tests/ui/on-unimplemented/feature-gate-on-unimplemented.stderr
+++ b/tests/ui/on-unimplemented/feature-gate-on-unimplemented.stderr
@@ -1,11 +1,12 @@
-error[E0658]: this is an internal attribute that will never be stable
+error[E0658]: use of an internal attribute
   --> $DIR/feature-gate-on-unimplemented.rs:3:1
    |
 LL | #[rustc_on_unimplemented = "test error `{Self}` with `{Bar}`"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_on_unimplemented]` attribute is an internal implementation detail that will never be stable
+   = note: see `#[diagnostic::on_unimplemented]` for the stable equivalent of this attribute
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/rustdoc/feature-gate-doc_primitive.rs b/tests/ui/rustdoc/feature-gate-doc_primitive.rs
index 78fcd90752e..dbf92f19378 100644
--- a/tests/ui/rustdoc/feature-gate-doc_primitive.rs
+++ b/tests/ui/rustdoc/feature-gate-doc_primitive.rs
@@ -1,5 +1,7 @@
 #[rustc_doc_primitive = "usize"]
-//~^ ERROR `rustc_doc_primitive` is a rustc internal attribute
+//~^ ERROR use of an internal attribute [E0658]
+//~| NOTE the `#[rustc_doc_primitive]` attribute is an internal implementation detail that will never be stable
+//~| NOTE the `#[rustc_doc_primitive]` attribute is used by the standard library to provide a way to generate documentation for primitive types
 /// Some docs
 mod usize {}
 
diff --git a/tests/ui/rustdoc/feature-gate-doc_primitive.stderr b/tests/ui/rustdoc/feature-gate-doc_primitive.stderr
index e74b1322b25..0b1af78b504 100644
--- a/tests/ui/rustdoc/feature-gate-doc_primitive.stderr
+++ b/tests/ui/rustdoc/feature-gate-doc_primitive.stderr
@@ -1,11 +1,12 @@
-error[E0658]: `rustc_doc_primitive` is a rustc internal attribute
+error[E0658]: use of an internal attribute
   --> $DIR/feature-gate-doc_primitive.rs:1:1
    |
 LL | #[rustc_doc_primitive = "usize"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_doc_primitive]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[rustc_doc_primitive]` attribute is used by the standard library to provide a way to generate documentation for primitive types
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/tool-attributes/diagnostic_item.rs b/tests/ui/tool-attributes/diagnostic_item.rs
index 26a52ce60cf..806b140feba 100644
--- a/tests/ui/tool-attributes/diagnostic_item.rs
+++ b/tests/ui/tool-attributes/diagnostic_item.rs
@@ -1,3 +1,5 @@
-#[rustc_diagnostic_item = "foomp"] //~ ERROR compiler internal support for linting
+#[rustc_diagnostic_item = "foomp"]
+//~^ ERROR use of an internal attribute [E0658]
+//~| NOTE the `#[rustc_diagnostic_item]` attribute allows the compiler to reference types from the standard library for diagnostic purposes
 struct Foomp;
 fn main() {}
diff --git a/tests/ui/tool-attributes/diagnostic_item.stderr b/tests/ui/tool-attributes/diagnostic_item.stderr
index c6ae5a38594..d37044281a1 100644
--- a/tests/ui/tool-attributes/diagnostic_item.stderr
+++ b/tests/ui/tool-attributes/diagnostic_item.stderr
@@ -1,11 +1,11 @@
-error[E0658]: diagnostic items compiler internal support for linting
+error[E0658]: use of an internal attribute
   --> $DIR/diagnostic_item.rs:1:1
    |
 LL | #[rustc_diagnostic_item = "foomp"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_diagnostic_item]` attribute allows the compiler to reference types from the standard library for diagnostic purposes
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/traits/default-method/rustc_must_implement_one_of_gated.rs b/tests/ui/traits/default-method/rustc_must_implement_one_of_gated.rs
index 27e70556b7a..47cc9f5f960 100644
--- a/tests/ui/traits/default-method/rustc_must_implement_one_of_gated.rs
+++ b/tests/ui/traits/default-method/rustc_must_implement_one_of_gated.rs
@@ -1,5 +1,7 @@
 #[rustc_must_implement_one_of(eq, neq)]
-//~^ ERROR the `#[rustc_must_implement_one_of]` attribute is used to change minimal complete definition of a trait, it's currently in experimental form and should be changed before being exposed outside of the std
+//~^ ERROR use of an internal attribute [E0658]
+//~| NOTE the `#[rustc_must_implement_one_of]` attribute is an internal implementation detail that will never be stable
+//~| NOTE the `#[rustc_must_implement_one_of]` attribute is used to change minimal complete definition of a trait. Its syntax and semantics are highly experimental and will be subject to change before stabilization
 trait Equal {
     fn eq(&self, other: &Self) -> bool {
         !self.neq(other)
diff --git a/tests/ui/traits/default-method/rustc_must_implement_one_of_gated.stderr b/tests/ui/traits/default-method/rustc_must_implement_one_of_gated.stderr
index 162c3d36cb1..4d44ceff98a 100644
--- a/tests/ui/traits/default-method/rustc_must_implement_one_of_gated.stderr
+++ b/tests/ui/traits/default-method/rustc_must_implement_one_of_gated.stderr
@@ -1,11 +1,12 @@
-error[E0658]: the `#[rustc_must_implement_one_of]` attribute is used to change minimal complete definition of a trait, it's currently in experimental form and should be changed before being exposed outside of the std
+error[E0658]: use of an internal attribute
   --> $DIR/rustc_must_implement_one_of_gated.rs:1:1
    |
 LL | #[rustc_must_implement_one_of(eq, neq)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: the `#[rustc_must_implement_one_of]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[rustc_must_implement_one_of]` attribute is used to change minimal complete definition of a trait. Its syntax and semantics are highly experimental and will be subject to change before stabilization
 
 error: aborting due to 1 previous error