Auto merge of #130414 - compiler-errors:precise-capturing-arg-valid, r=jieyouxu

Do precise capturing arg validation in resolve

Moves the validation of precise capturing args (`use<T, N>`) out of `resolve_bound_vars` and into `rustc_resolve`. This both simplifies the impl and fixes a bug when we have `use<arg>` where `arg` is one of the function args.

This also introduces new error codes specifically for precise capturing, to avoid reusing the other error codes which are not as accurate.

Fixes #130399

3 files changed, 32 insertions, 0 deletions

diff --git a/compiler/rustc_error_codes/src/error_codes/E0799.md b/compiler/rustc_error_codes/src/error_codes/E0799.md
new file mode 100644
index 00000000000..38ebc840604
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0799.md
@@ -0,0 +1,19 @@
+Something other than a type or const parameter has been used when one was
+expected.
+
+Erroneous code example:
+
+```compile_fail,E0799
+fn bad1() -> impl Sized + use<main> {}
+
+fn bad2(x: ()) -> impl Sized + use<x> {}
+
+fn main() {}
+```
+
+In the given examples, for `bad1`, the name `main` corresponds to a function
+rather than a type or const parameter. In `bad2`, the name `x` corresponds to
+a function argument rather than a type or const parameter.
+
+Only type and const parameters, including `Self`, may be captured by
+`use<...>` precise capturing bounds.
diff --git a/compiler/rustc_error_codes/src/error_codes/E0800.md b/compiler/rustc_error_codes/src/error_codes/E0800.md
new file mode 100644
index 00000000000..3e08cd499b7
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0800.md
@@ -0,0 +1,11 @@
+A type or const parameter of the given name is not in scope.
+
+Erroneous code examples:
+
+```compile_fail,E0800
+fn missing() -> impl Sized + use<T> {}
+```
+
+To fix this error, please verify you didn't misspell the type or const
+parameter, or double-check if you forgot to declare the parameter in
+the list of generics.
diff --git a/compiler/rustc_error_codes/src/lib.rs b/compiler/rustc_error_codes/src/lib.rs
index 150f99a3ee7..d6f0206b0de 100644
--- a/compiler/rustc_error_codes/src/lib.rs
+++ b/compiler/rustc_error_codes/src/lib.rs
@@ -538,6 +538,8 @@ E0795: 0795,
 E0796: 0796,
 E0797: 0797,
 E0798: 0798,
+E0799: 0799,
+E0800: 0800,
         );
     )
 }