[clang] [clang-format] Annotate the l_paren of function pointer types (PR #109229)

[Owen Pan via cfe-commits]

https://github.com/owenca created https://github.com/llvm/llvm-project/pull/109229

Fixes #109146.

>From 84c166dfabc3f314cd922baa3933b3d0ea11e08e Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Wed, 18 Sep 2024 21:03:24 -0700
Subject: [PATCH] [clang-format] Annotate the l_paren of function pointer types

Fixes #109146.
---
 clang/lib/Format/TokenAnnotator.cpp           | 14 ++++++++------
 clang/unittests/Format/TokenAnnotatorTest.cpp |  6 ++++++
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 6f09835bad3a83..9e5f5588592199 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -486,16 +486,18 @@ class AnnotatingParser {
         }
       }
 
-      if (CurrentToken->Previous->is(TT_PointerOrReference) &&
-          CurrentToken->Previous->Previous->isOneOf(tok::l_paren,
-                                                    tok::coloncolon)) {
+      const auto &Prev = *CurrentToken->Previous;
+      if (Prev.is(TT_PointerOrReference) &&
+          Prev.Previous->isOneOf(tok::l_paren, tok::coloncolon)) {
         ProbablyFunctionType = true;
       }
       if (CurrentToken->is(tok::comma))
         MightBeFunctionType = false;
-      if (CurrentToken->Previous->is(TT_BinaryOperator))
+      if (Prev.is(TT_BinaryOperator))
         Contexts.back().IsExpression = true;
       if (CurrentToken->is(tok::r_paren)) {
+        if (Prev.is(TT_PointerOrReference) && Prev.Previous == &OpeningParen)
+          MightBeFunctionType = true;
         if (OpeningParen.isNot(TT_CppCastLParen) && MightBeFunctionType &&
             ProbablyFunctionType && CurrentToken->Next &&
             (CurrentToken->Next->is(tok::l_paren) ||
@@ -568,8 +570,8 @@ class AnnotatingParser {
       bool ProbablyFunctionTypeLParen =
           (CurrentToken->is(tok::l_paren) && CurrentToken->Next &&
            CurrentToken->Next->isOneOf(tok::star, tok::amp, tok::caret));
-      if ((CurrentToken->Previous->isOneOf(tok::kw_const, tok::kw_auto) ||
-           CurrentToken->Previous->isTypeName(LangOpts)) &&
+      if ((Prev.isOneOf(tok::kw_const, tok::kw_auto) ||
+           Prev.isTypeName(LangOpts)) &&
           !(CurrentToken->is(tok::l_brace) ||
             (CurrentToken->is(tok::l_paren) && !ProbablyFunctionTypeLParen))) {
         Contexts.back().IsExpression = false;
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index 34c03d668a9a0a..b5f03d4f851e6e 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -789,6 +789,12 @@ TEST_F(TokenAnnotatorTest, UnderstandsCasts) {
   ASSERT_EQ(Tokens.size(), 13u) << Tokens;
   EXPECT_TOKEN(Tokens[5], tok::r_paren, TT_CastRParen);
 
+  Tokens = annotate("return (Foo (*)(void *, Bar, ...))&foo;");
+  ASSERT_EQ(Tokens.size(), 19u) << Tokens;
+  EXPECT_TOKEN(Tokens[3], tok::l_paren, TT_FunctionTypeLParen);
+  EXPECT_TOKEN(Tokens[14], tok::r_paren, TT_CastRParen);
+  EXPECT_TOKEN(Tokens[15], tok::amp, TT_UnaryOperator);
+
   auto Style = getLLVMStyle();
   Style.TypeNames.push_back("Foo");
   Tokens = annotate("#define FOO(bar) foo((Foo)&bar)", Style);