[clang-format] Fix a bug in parsing C-style cast of lambdas

[owenca]

Fix #135959

[llvmbot]

@llvm/pr-subscribers-clang-format

Author: Owen Pan (owenca)

Changes

Fix #135959

---

Full diff: https://github.com/llvm/llvm-project/pull/136099.diff

2 Files Affected:

• (modified) clang/lib/Format/UnwrappedLineParser.cpp (+2-1)
• (modified) clang/unittests/Format/TokenAnnotatorTest.cpp (+5)

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index b9430d4389feb..4442e965e0f51 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -2371,7 +2371,8 @@ bool UnwrappedLineParser::tryToParseLambdaIntroducer() {
   if ((Previous && ((Previous->Tok.getIdentifierInfo() &&
                      !Previous->isOneOf(tok::kw_return, tok::kw_co_await,
                                         tok::kw_co_yield, tok::kw_co_return)) ||
-                    Previous->closesScope())) ||
+                    (Previous->closesScope() &&
+                     !Previous->endsSequence(tok::r_paren, tok::greater)))) ||
       LeftSquare->isCppStructuredBinding(IsCpp)) {
     return false;
   }
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index 2c7319ccefec2..7a07fbd0250be 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -2159,6 +2159,11 @@ TEST_F(TokenAnnotatorTest, UnderstandsLambdas) {
   // FIXME:
   // EXPECT_TOKEN(Tokens[13], tok::l_paren, TT_LambdaDefinitionLParen);
   EXPECT_TOKEN(Tokens[17], tok::l_brace, TT_LambdaLBrace);
+
+  Tokens = annotate("auto foo{(std::function<int()>)[] { return 0; }};");
+  ASSERT_EQ(Tokens.size(), 23u) << Tokens;
+  EXPECT_TOKEN(Tokens[13], tok::l_square, TT_LambdaLSquare);
+  EXPECT_TOKEN(Tokens[15], tok::l_brace, TT_LambdaLBrace);
 }
 
 TEST_F(TokenAnnotatorTest, UnderstandsFunctionAnnotations) {

[HazardyKnusperkeks]

And if it is casted to int(*)?

I know we didn't annotate stuff here, it is hard to detect if this is a cast, but is there maybe a different way which would be a bit more resilient?

[owenca]

I've added the handling of casting to a function pointer, the only other case I can think of.