[clang] [clang-format] Fix a regression in annotating goto labels (PR #92494)

[Owen Pan via cfe-commits]

https://github.com/owenca created https://github.com/llvm/llvm-project/pull/92494

Fixes #92300.

>From 530b15d68c66b0f1414329a8e190b27c2e6bf106 Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Thu, 16 May 2024 20:49:17 -0700
Subject: [PATCH] [clang-format] Fix a regression in annotating goto labels

Fixes #92300.
---
 clang/lib/Format/UnwrappedLineParser.cpp      |  9 ++-------
 clang/unittests/Format/TokenAnnotatorTest.cpp | 13 +++++++++++++
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index b15a87327240b..3dd10f6bd2b31 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -1189,12 +1189,6 @@ void UnwrappedLineParser::parsePPDefine() {
     return;
   }
 
-  if (FormatTok->is(tok::identifier) &&
-      Tokens->peekNextToken()->is(tok::colon)) {
-    nextToken();
-    nextToken();
-  }
-
   // Errors during a preprocessor directive can only affect the layout of the
   // preprocessor directive, and thus we ignore them. An alternative approach
   // would be to use the same approach we use on the file level (no
@@ -1681,7 +1675,8 @@ void UnwrappedLineParser::parseStructuralElement(
     if (!Style.isJavaScript() && !Style.isVerilog() && !Style.isTableGen() &&
         Tokens->peekNextToken()->is(tok::colon) && !Line->MustBeDeclaration) {
       nextToken();
-      Line->Tokens.begin()->Tok->MustBreakBefore = true;
+      if (!Line->InMacroBody || CurrentLines->size() > 1)
+        Line->Tokens.begin()->Tok->MustBreakBefore = true;
       FormatTok->setFinalizedType(TT_GotoLabelColon);
       parseLabel(!Style.IndentGotoLabels);
       if (HasLabel)
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index aadfa6dc0165c..d9c6e8cc1c877 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -2581,15 +2581,28 @@ TEST_F(TokenAnnotatorTest, UnderstandsLabels) {
   auto Tokens = annotate("{ x: break; }");
   ASSERT_EQ(Tokens.size(), 7u) << Tokens;
   EXPECT_TOKEN(Tokens[2], tok::colon, TT_GotoLabelColon);
+
   Tokens = annotate("{ case x: break; }");
   ASSERT_EQ(Tokens.size(), 8u) << Tokens;
   EXPECT_TOKEN(Tokens[3], tok::colon, TT_CaseLabelColon);
+
   Tokens = annotate("{ x: { break; } }");
   ASSERT_EQ(Tokens.size(), 9u) << Tokens;
   EXPECT_TOKEN(Tokens[2], tok::colon, TT_GotoLabelColon);
+
   Tokens = annotate("{ case x: { break; } }");
   ASSERT_EQ(Tokens.size(), 10u) << Tokens;
   EXPECT_TOKEN(Tokens[3], tok::colon, TT_CaseLabelColon);
+
+  Tokens = annotate("#define FOO label:");
+  ASSERT_EQ(Tokens.size(), 6u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::colon, TT_GotoLabelColon);
+
+  Tokens = annotate("#define FOO \\\n"
+                    "  label:\\\n"
+                    "  break;");
+  ASSERT_EQ(Tokens.size(), 8u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::colon, TT_GotoLabelColon);
 }
 
 TEST_F(TokenAnnotatorTest, UnderstandsNestedBlocks) {