Rollup merge of #142671 - davidtwco:no-default-bounds-attr, r=lcnr

add #![rustc_no_implicit_bounds]

Follow-up from rust-lang/rust#137944.

Adds a new `rustc_attrs` attribute that stops rustc from adding any default bounds. Useful for tests where default bounds just add noise and make debugging harder.

After reviewing all tests with `?Sized`, these tests seem like they could probably benefit from `#![rustc_no_implicit_bounds]`.

- Skipping most of `tests/ui/unsized` as these seem to want to test `?Sized`
- Skipping tests that used `Box<T>` because it's still bound by `T: MetaSized`
- Skipping parsing or other tests that cared about `?Sized` syntactically
- Skipping tests for `derive(CoercePointee)` because this appears to check that the pointee type is relaxed with `?Sized` explicitly

r? `@lcnr`

1 files changed, 4 insertions, 4 deletions

diff --git a/tests/ui/traits/overflow-computing-ambiguity.stderr b/tests/ui/traits/overflow-computing-ambiguity.stderr
index a2e255865bf..f3e91a29a9c 100644
--- a/tests/ui/traits/overflow-computing-ambiguity.stderr
+++ b/tests/ui/traits/overflow-computing-ambiguity.stderr
@@ -1,5 +1,5 @@
 error[E0283]: type annotations needed
-  --> $DIR/overflow-computing-ambiguity.rs:12:5
+  --> $DIR/overflow-computing-ambiguity.rs:15:5
    |
 LL |     hello();
    |     ^^^^^ cannot infer type of the type parameter `T` declared on the function `hello`
@@ -9,10 +9,10 @@ LL |     hello();
              Foo<'a, &'a T>
              Foo<'static, i32>
 note: required by a bound in `hello`
-  --> $DIR/overflow-computing-ambiguity.rs:9:22
+  --> $DIR/overflow-computing-ambiguity.rs:12:13
    |
-LL | fn hello<T: ?Sized + Hello>() {}
-   |                      ^^^^^ required by this bound in `hello`
+LL | fn hello<T: Hello>() {}
+   |             ^^^^^ required by this bound in `hello`
 help: consider specifying the generic argument
    |
 LL |     hello::<T>();