Rollup merge of #104148 - fmease:fix-104140, r=petrochenkov

Visit attributes of trait impl items during AST validation

Fixes #104140.

This fix might not be backward compatible (in practice) since we now validate more attributes than before.
Should I write more tests?

`@rustbot` label A-attributes

2 files changed, 23 insertions, 0 deletions

diff --git a/src/test/ui/on-unimplemented/issue-104140.rs b/src/test/ui/on-unimplemented/issue-104140.rs
new file mode 100644
index 00000000000..ade3f727004
--- /dev/null
+++ b/src/test/ui/on-unimplemented/issue-104140.rs
@@ -0,0 +1,8 @@
+#![feature(rustc_attrs)]
+
+trait Foo {}
+
+#[rustc_on_unimplemented] //~ ERROR malformed `rustc_on_unimplemented` attribute input
+impl Foo for u32 {}
+
+fn main() {}
diff --git a/src/test/ui/on-unimplemented/issue-104140.stderr b/src/test/ui/on-unimplemented/issue-104140.stderr
new file mode 100644
index 00000000000..ddb1f50f0bb
--- /dev/null
+++ b/src/test/ui/on-unimplemented/issue-104140.stderr
@@ -0,0 +1,15 @@
+error: malformed `rustc_on_unimplemented` attribute input
+  --> $DIR/issue-104140.rs:5:1
+   |
+LL | #[rustc_on_unimplemented]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: the following are the possible correct uses
+   |
+LL | #[rustc_on_unimplemented = "message"]
+   | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+LL | #[rustc_on_unimplemented(/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...")]
+   | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to previous error
+