[clang-format] Correctly annotate token-pasted function decl names (llvm#142337)

Fix llvm#142178

(cherry picked from commit 7bf5862)

Author: owenca

clang/lib/Format/TokenAnnotator.cpp

@@ -3839,6 +3839,8 @@ static bool isFunctionDeclarationName(const LangOptions &LangOpts,
   } else {
     if (Current.isNot(TT_StartOfName) || Current.NestingLevel != 0)
       return false;
+    while (Next && Next->startsSequence(tok::hashhash, tok::identifier))
+      Next = Next->Next->Next;
     for (; Next; Next = Next->Next) {
       if (Next->is(TT_TemplateOpener) && Next->MatchingParen) {
         Next = Next->MatchingParen;

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -2187,6 +2187,13 @@ TEST_F(TokenAnnotatorTest, UnderstandsFunctionDeclarationNames) {
   EXPECT_TOKEN(Tokens[1], tok::identifier, TT_FunctionDeclarationName);
   EXPECT_TOKEN(Tokens[2], tok::l_paren, TT_FunctionDeclarationLParen);
 
+  Tokens = annotate("#define FUNC(foo, bar, baz) \\\n"
+                    "  auto foo##bar##baz() -> Type {}");
+  ASSERT_EQ(Tokens.size(), 23u) << Tokens;
+  EXPECT_TOKEN(Tokens[11], tok::identifier, TT_FunctionDeclarationName);
+  EXPECT_TOKEN(Tokens[16], tok::l_paren, TT_FunctionDeclarationLParen);
+  EXPECT_TOKEN(Tokens[18], tok::arrow, TT_TrailingReturnArrow);
+
   Tokens = annotate("int iso_time(time_t);");
   ASSERT_EQ(Tokens.size(), 7u) << Tokens;
   EXPECT_TOKEN(Tokens[1], tok::identifier, TT_FunctionDeclarationName);