From 0017822b708d2dde46fa603592d322951dc7ba0a Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 8 Feb 2023 17:56:04 +0000
Subject: [PATCH] Do not eagerly recover for bad impl-trait in macros

---
 compiler/rustc_parse/src/parser/ty.rs        |  5 +++--
 tests/ui/parser/bad-recover-kw-after-impl.rs | 15 +++++++++++++++
 tests/ui/parser/bad-recover-ty-after-impl.rs | 17 +++++++++++++++++
 3 files changed, 35 insertions(+), 2 deletions(-)
 create mode 100644 tests/ui/parser/bad-recover-kw-after-impl.rs
 create mode 100644 tests/ui/parser/bad-recover-ty-after-impl.rs

diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs
index a19ea04fa5e..5b92563fc35 100644
--- a/compiler/rustc_parse/src/parser/ty.rs
+++ b/compiler/rustc_parse/src/parser/ty.rs
@@ -694,8 +694,9 @@ fn parse_generic_bounds_common(
         // `where`, so stop if it's it.
         // We also continue if we find types (not traits), again for error recovery.
         while self.can_begin_bound()
-            || self.token.can_begin_type()
-            || (self.token.is_reserved_ident() && !self.token.is_keyword(kw::Where))
+            || (self.may_recover()
+                && (self.token.can_begin_type()
+                    || (self.token.is_reserved_ident() && !self.token.is_keyword(kw::Where))))
         {
             if self.token.is_keyword(kw::Dyn) {
                 // Account for `&dyn Trait + dyn Other`.
diff --git a/tests/ui/parser/bad-recover-kw-after-impl.rs b/tests/ui/parser/bad-recover-kw-after-impl.rs
new file mode 100644
index 00000000000..218cd767859
--- /dev/null
+++ b/tests/ui/parser/bad-recover-kw-after-impl.rs
@@ -0,0 +1,15 @@
+// check-pass
+
+// edition:2021
+// for the `impl` + keyword test
+
+macro_rules! impl_primitive {
+    ($ty:ty) => {
+        compile_error!("whoops");
+    };
+    (impl async) => {};
+}
+
+impl_primitive!(impl async);
+
+fn main() {}
diff --git a/tests/ui/parser/bad-recover-ty-after-impl.rs b/tests/ui/parser/bad-recover-ty-after-impl.rs
new file mode 100644
index 00000000000..510e08ba091
--- /dev/null
+++ b/tests/ui/parser/bad-recover-ty-after-impl.rs
@@ -0,0 +1,17 @@
+// check-pass
+
+macro_rules! impl_primitive {
+    ($ty:ty) => { impl_primitive!(impl $ty); };
+    (impl $ty:ty) => { fn a(_: $ty) {} }
+}
+
+impl_primitive! { u8 }
+
+macro_rules! test {
+    ($ty:ty) => { compile_error!("oh no"); };
+    (impl &) => {};
+}
+
+test!(impl &);
+
+fn main() {}
-- 
2.44.0