1 files changed, 10 insertions, 0 deletions
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 14fe9f7cf37..4377a782864 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -2706,6 +2706,16 @@ void Parser::ParseCXXMemberSpecification(SourceLocation RecordLoc,
     // and the only possible place for them to appertain
     // to the class would be between class-key and class-name.
     CheckMisplacedCXX11Attribute(Attrs, AttrFixitLoc);
+
+    // ParseClassSpecifier() does only a superficial check for attributes before
+    // deciding to call this method.  For example, for
+    // `class C final alignas ([l) {` it will decide that this looks like a
+    // misplaced attribute since it sees `alignas '(' ')'`.  But the actual
+    // attribute parsing code will try to parse the '[' as a constexpr lambda
+    // and consume enough tokens that the alignas parsing code will eat the
+    // opening '{'.  So bail out if the next token isn't one we expect.
+    if (!Tok.is(tok::colon) && !Tok.is(tok::l_brace))
+      return;
   }
 
   if (Tok.is(tok::colon)) {