[clang-format] Annotate ::operator as FunctionDeclarationName (#111115)

Fixes #111011.

Author: owenca

clang/lib/Format/TokenAnnotator.cpp

@@ -3738,6 +3738,13 @@ static bool isFunctionDeclarationName(const LangOptions &LangOpts,
 
   const auto *Prev = Current.getPreviousNonComment();
   assert(Prev);
+
+  if (Prev->is(tok::coloncolon))
+    Prev = Prev->Previous;
+
+  if (!Prev)
+    return false;
+
   const auto &Previous = *Prev;
 
   if (const auto *PrevPrev = Previous.getPreviousNonComment();

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -1007,6 +1007,14 @@ TEST_F(TokenAnnotatorTest, UnderstandsOverloadedOperators) {
   EXPECT_TOKEN(Tokens[6], tok::r_paren, TT_OverloadedOperator);
   EXPECT_TOKEN(Tokens[7], tok::l_paren, TT_OverloadedOperatorLParen);
   EXPECT_TOKEN(Tokens[9], tok::amp, TT_PointerOrReference);
+
+  Tokens = annotate("friend ostream& ::operator<<(ostream& lhs, foo& rhs);");
+  ASSERT_EQ(Tokens.size(), 17u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::kw_operator, TT_FunctionDeclarationName);
+  EXPECT_TOKEN(Tokens[5], tok::lessless, TT_OverloadedOperator);
+  EXPECT_TOKEN(Tokens[6], tok::l_paren, TT_OverloadedOperatorLParen);
+  EXPECT_TOKEN(Tokens[8], tok::amp, TT_PointerOrReference);
+  EXPECT_TOKEN(Tokens[12], tok::amp, TT_PointerOrReference);
 }
 
 TEST_F(TokenAnnotatorTest, OverloadedOperatorInTemplate) {