Rollup merge of #133424 - Nadrieril:guard-patterns-parsing, r=fee1-dead

Parse guard patterns

This implements the parsing of [RFC3637 Guard Patterns](https://rust-lang.github.io/rfcs/3637-guard-patterns.html) (see also [tracking issue](https://github.com/rust-lang/rust/issues/129967)). This PR is extracted from https://github.com/rust-lang/rust/pull/129996 with minor modifications.

cc `@max-niederman`

2 files changed, 22 insertions, 2 deletions

diff --git a/tests/ui/pattern/bindings-after-at/nested-type-ascription-syntactically-invalid.stderr b/tests/ui/pattern/bindings-after-at/nested-type-ascription-syntactically-invalid.stderr
index da8f4ca5f0c..6ce8f6d31a0 100644
--- a/tests/ui/pattern/bindings-after-at/nested-type-ascription-syntactically-invalid.stderr
+++ b/tests/ui/pattern/bindings-after-at/nested-type-ascription-syntactically-invalid.stderr
@@ -6,11 +6,11 @@ LL |     let a: u8 @ b = 0;
    |          |
    |          while parsing the type for `a`
 
-error: expected one of `)`, `,`, `@`, or `|`, found `:`
+error: expected one of `)`, `,`, `@`, `if`, or `|`, found `:`
   --> $DIR/nested-type-ascription-syntactically-invalid.rs:24:15
    |
 LL |     let a @ (b: u8);
-   |               ^ expected one of `)`, `,`, `@`, or `|`
+   |               ^ expected one of `)`, `,`, `@`, `if`, or `|`
    |
    = note: type ascription syntax has been removed, see issue #101728 <https://github.com/rust-lang/rust/issues/101728>
 
diff --git a/tests/ui/pattern/rfc-3637-guard-patterns/macro-rules.rs b/tests/ui/pattern/rfc-3637-guard-patterns/macro-rules.rs
new file mode 100644
index 00000000000..76681f45bb3
--- /dev/null
+++ b/tests/ui/pattern/rfc-3637-guard-patterns/macro-rules.rs
@@ -0,0 +1,20 @@
+//@ run-pass
+//! Tests that the addition of guard patterns does not change the behavior of the `pat` macro
+//! fragment.
+#![feature(guard_patterns)]
+#![allow(incomplete_features)]
+
+macro_rules! has_guard {
+    ($p:pat) => {
+        false
+    };
+    ($p:pat if $e:expr) => {
+        true
+    };
+}
+
+fn main() {
+    assert_eq!(has_guard!(Some(_)), false);
+    assert_eq!(has_guard!(Some(_) if true), true);
+    assert_eq!(has_guard!((Some(_) if true)), false);
+}