From 62ded071d588b92b394c4561d19d517d87074728 Mon Sep 17 00:00:00 2001
From: Takayuki Maeda <takoyaki0316@gmail.com>
Date: Tue, 22 Mar 2022 16:06:56 +0900
Subject: [PATCH] cancel a not emitted error after parsing const generic args

---
 compiler/rustc_parse/src/parser/path.rs              | 12 ++++++++----
 .../ice-const-generic-function-return-ty.rs          |  5 +++++
 .../ice-const-generic-function-return-ty.stderr      |  8 ++++++++
 3 files changed, 21 insertions(+), 4 deletions(-)
 create mode 100644 src/test/ui/const-generics/ice-const-generic-function-return-ty.rs
 create mode 100644 src/test/ui/const-generics/ice-const-generic-function-return-ty.stderr

diff --git a/compiler/rustc_parse/src/parser/path.rs b/compiler/rustc_parse/src/parser/path.rs
index 17c57867cf9..07ce879de8f 100644
--- a/compiler/rustc_parse/src/parser/path.rs
+++ b/compiler/rustc_parse/src/parser/path.rs
@@ -630,10 +630,14 @@ impl<'a> Parser<'a> {
                 Ok(ty) => GenericArg::Type(ty),
                 Err(err) => {
                     if is_const_fn {
-                        if let Ok(expr) = (*snapshot).parse_expr_res(Restrictions::CONST_EXPR, None)
-                        {
-                            self.restore_snapshot(snapshot);
-                            return Ok(Some(self.dummy_const_arg_needs_braces(err, expr.span)));
+                        match (*snapshot).parse_expr_res(Restrictions::CONST_EXPR, None) {
+                            Ok(expr) => {
+                                self.restore_snapshot(snapshot);
+                                return Ok(Some(self.dummy_const_arg_needs_braces(err, expr.span)));
+                            }
+                            Err(err) => {
+                                err.cancel();
+                            }
                         }
                     }
                     // Try to recover from possible `const` arg without braces.
diff --git a/src/test/ui/const-generics/ice-const-generic-function-return-ty.rs b/src/test/ui/const-generics/ice-const-generic-function-return-ty.rs
new file mode 100644
index 00000000000..2bf628af8a7
--- /dev/null
+++ b/src/test/ui/const-generics/ice-const-generic-function-return-ty.rs
@@ -0,0 +1,5 @@
+// #95163
+fn return_ty() -> impl Into<<() as Reexported;
+//~^ ERROR expected one of `(`, `::`, `<`, or `>`, found `;`
+
+fn main() {}
diff --git a/src/test/ui/const-generics/ice-const-generic-function-return-ty.stderr b/src/test/ui/const-generics/ice-const-generic-function-return-ty.stderr
new file mode 100644
index 00000000000..a72f5800a07
--- /dev/null
+++ b/src/test/ui/const-generics/ice-const-generic-function-return-ty.stderr
@@ -0,0 +1,8 @@
+error: expected one of `(`, `::`, `<`, or `>`, found `;`
+  --> $DIR/ice-const-generic-function-return-ty.rs:2:46
+   |
+LL | fn return_ty() -> impl Into<<() as Reexported;
+   |                                              ^ expected one of `(`, `::`, `<`, or `>`
+
+error: aborting due to previous error
+