Rollup merge of rust-lang#120183 - Zalathar:test-closure, r=compiler-errors

Add `#[coverage(off)]` to closures introduced by `#[test]` and `#[bench]`

These closures are an internal implementation detail of the `#[test]` and `#[bench]` attribute macros, so from a user perspective there is no reason to instrument them for coverage.

Skipping them makes coverage reports slightly cleaner, and will also allow other changes to span processing during coverage instrumentation, without having to worry about how they affect the `#[test]` macro.

The `#[coverage(off)]` attribute has no effect when `-Cinstrument-coverage` is not used.

Fixes rust-lang#120046.

---

Note that this PR has no effect on the user-written function that has the `#[test]` attribute attached to it. That function will still be instrumented as normal.

Author: fmease

core/src/macros/mod.rs

@@ -1596,7 +1596,7 @@ pub(crate) mod builtin {
     ///
     /// [the reference]: ../../../reference/attributes/testing.html#the-test-attribute
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[allow_internal_unstable(test, rustc_attrs)]
+    #[allow_internal_unstable(test, rustc_attrs, coverage_attribute)]
     #[rustc_builtin_macro]
     pub macro test($item:item) {
         /* compiler built-in */
@@ -1609,7 +1609,7 @@ pub(crate) mod builtin {
         soft,
         reason = "`bench` is a part of custom test frameworks which are unstable"
     )]
-    #[allow_internal_unstable(test, rustc_attrs)]
+    #[allow_internal_unstable(test, rustc_attrs, coverage_attribute)]
     #[rustc_builtin_macro]
     pub macro bench($item:item) {
         /* compiler built-in */