parser: don't use `unreachable!()` in `fn unexpected`.

2 files changed, 30 insertions, 0 deletions

diff --git a/src/test/ui/parser/issue-66357-unexpected-unreachable.rs b/src/test/ui/parser/issue-66357-unexpected-unreachable.rs
new file mode 100644
index 00000000000..1730adfa914
--- /dev/null
+++ b/src/test/ui/parser/issue-66357-unexpected-unreachable.rs
@@ -0,0 +1,14 @@
+// The problem in #66357 was that the call trace:
+//
+// - parse_fn_block_decl
+// - expect_or
+// - unexpected
+// - expect_one_of
+// - expected_one_of_not_found
+// - recover_closing_delimiter
+//
+// ended up bubbling up `Ok(true)` to `unexpected` which then used `unreachable!()`.
+
+fn f() { |[](* }
+//~^ ERROR expected one of `,` or `:`, found `(`
+//~| ERROR expected one of `)`, `-`, `_`, `box`, `mut`, `ref`, `|`, identifier, or path, found `*`
diff --git a/src/test/ui/parser/issue-66357-unexpected-unreachable.stderr b/src/test/ui/parser/issue-66357-unexpected-unreachable.stderr
new file mode 100644
index 00000000000..00d84e2afe3
--- /dev/null
+++ b/src/test/ui/parser/issue-66357-unexpected-unreachable.stderr
@@ -0,0 +1,16 @@
+error: expected one of `,` or `:`, found `(`
+  --> $DIR/issue-66357-unexpected-unreachable.rs:12:13
+   |
+LL | fn f() { |[](* }
+   |             ^ expected one of `,` or `:`
+
+error: expected one of `)`, `-`, `_`, `box`, `mut`, `ref`, `|`, identifier, or path, found `*`
+  --> $DIR/issue-66357-unexpected-unreachable.rs:12:14
+   |
+LL | fn f() { |[](* }
+   |             -^ help: `)` may belong here
+   |             |
+   |             unclosed delimiter
+
+error: aborting due to 2 previous errors
+