Rollup merge of #82770 - m-ou-se:assert-match, r=joshtriplett

Add assert_matches macro.

This adds `assert_matches!(expression, pattern)`.

Unlike the other asserts, this one ~~consumes the expression~~ may consume the expression, to be able to match the pattern. (It could add a `&` implicitly, but that's noticable in the pattern, and will make a consuming guard impossible.)

See https://github.com/rust-lang/rust/issues/62633#issuecomment-790737853

This re-uses the same `left: .. right: ..` output as the `assert_eq` and `assert_ne` macros, but with the pattern as the right part:

assert_eq:
```
assertion failed: `(left == right)`
  left: `Some("asdf")`,
 right: `None`
```
assert_matches:
```
assertion failed: `(left matches right)`
  left: `Ok("asdf")`,
 right: `Err(_)`
```

cc ```@cuviper```
This commit is contained in:
Mara 2021-03-05 10:57:23 +01:00 committed by GitHub
commit 04045cc83f
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3 changed files with 141 additions and 27 deletions

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@ -228,6 +228,7 @@
#![feature(arbitrary_self_types)]
#![feature(array_error_internals)]
#![feature(asm)]
#![feature(assert_matches)]
#![feature(associated_type_bounds)]
#![feature(atomic_mut_ptr)]
#![feature(box_syntax)]
@ -552,8 +553,8 @@ pub use std_detect::detect;
#[stable(feature = "rust1", since = "1.0.0")]
#[allow(deprecated, deprecated_in_future)]
pub use core::{
assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne, matches, r#try, todo,
unimplemented, unreachable, write, writeln,
assert_eq, assert_matches, assert_ne, debug_assert, debug_assert_eq, debug_assert_matches,
debug_assert_ne, matches, r#try, todo, unimplemented, unreachable, write, writeln,
};
// Re-export built-in macros defined through libcore.