[clang-format] Fix a bug in annotating lambda l_square

[owenca]

Fixes #95072.

[llvmbot]

@llvm/pr-subscribers-clang-format

Author: Owen Pan (owenca)

Changes

Fixes #95072.

---

Full diff: https://github.com/llvm/llvm-project/pull/95084.diff

2 Files Affected:

• (modified) clang/lib/Format/UnwrappedLineParser.cpp (+2)
• (modified) clang/unittests/Format/TokenAnnotatorTest.cpp (+6)

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index eb96b54ec4c96..08387d2e08ee0 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -2257,6 +2257,8 @@ bool UnwrappedLineParser::tryToParseLambda() {
       break;
     case tok::kw_auto:
     case tok::kw_class:
+    case tok::kw_struct:
+    case tok::kw_union:
     case tok::kw_template:
     case tok::kw_typename:
     case tok::amp:
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index 3d609a1f041bc..0a1fb8c657ceb 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -1591,6 +1591,12 @@ TEST_F(TokenAnnotatorTest, UnderstandsLambdas) {
   EXPECT_TOKEN(Tokens[15], tok::arrow, TT_TrailingReturnArrow);
   EXPECT_TOKEN(Tokens[17], tok::l_brace, TT_LambdaLBrace);
 
+  Tokens = annotate("auto l = [] -> struct S { return {}; };");
+  ASSERT_EQ(Tokens.size(), 16u) << Tokens;
+  EXPECT_TOKEN(Tokens[3], tok::l_square, TT_LambdaLSquare);
+  EXPECT_TOKEN(Tokens[5], tok::arrow, TT_TrailingReturnArrow);
+  EXPECT_TOKEN(Tokens[8], tok::l_brace, TT_LambdaLBrace);
+
   Tokens = annotate("[] <typename T> () {}");
   ASSERT_EQ(Tokens.size(), 11u) << Tokens;
   EXPECT_TOKEN(Tokens[0], tok::l_square, TT_LambdaLSquare);