[llvm-branch-commits] [clang] release/20.x: [clang-format] Handle token-pasted function decl names (#142251) (PR #142282)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/142282

Backport 29f79ea3c59649f7686a09845665660c25ca3f9b

Requested by: @owenca

>From 06b99097672e06ec5fb4654a35fb3d677ad521b2 Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Sat, 31 May 2025 11:11:00 -0700
Subject: [PATCH] [clang-format] Handle token-pasted function decl names
 (#142251)

Fix #142178

(cherry picked from commit 29f79ea3c59649f7686a09845665660c25ca3f9b)
---
 clang/lib/Format/TokenAnnotator.cpp           | 7 ++++++-
 clang/unittests/Format/TokenAnnotatorTest.cpp | 7 +++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 11b941c5a0411..6ef2d665e1bc4 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -3967,8 +3967,13 @@ void TokenAnnotator::calculateFormattingInformation(AnnotatedLine &Line) const {
        Tok; Tok = Tok->Next) {
     if (Tok->is(TT_StartOfName))
       SeenName = true;
-    if (Tok->Previous->EndsCppAttributeGroup)
+    const auto *Previous = Tok->Previous;
+    if (Previous->EndsCppAttributeGroup) {
       AfterLastAttribute = Tok;
+    } else if (Line.InMacroBody &&
+               Previous->endsSequence(tok::hashhash, TT_StartOfName)) {
+      Tok->setType(TT_StartOfName);
+    }
     if (const bool IsCtorOrDtor = Tok->is(TT_CtorDtorDeclName);
         IsCtorOrDtor ||
         isFunctionDeclarationName(LangOpts, *Tok, Line, ClosingParen)) {
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index 757db66c3e298..2328dce8df8dc 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/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) \\\n"
+                    "  auto foo##bar() -> Type {}");
+  ASSERT_EQ(Tokens.size(), 19u) << Tokens;
+  EXPECT_TOKEN(Tokens[11], tok::identifier, TT_FunctionDeclarationName);
+  EXPECT_TOKEN(Tokens[12], tok::l_paren, TT_FunctionDeclarationLParen);
+  EXPECT_TOKEN(Tokens[14], 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);