[clang] [clang-format] Fix bugs in annotating arrows and square brackets (PR #160973)

via cfe-commits cfe-commits at lists.llvm.org
Sat Sep 27 20:18:26 PDT 2025


https://github.com/owenca updated https://github.com/llvm/llvm-project/pull/160973

>From ec8aadf1ec05897667e1c9df60ac9845d45f955a Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Fri, 26 Sep 2025 19:42:46 -0700
Subject: [PATCH 1/3] [clang-format] Fix bugs in annotating arrows and square
 brackets

Fixes #160518
---
 clang/lib/Format/TokenAnnotator.cpp           |  5 ----
 clang/lib/Format/UnwrappedLineParser.cpp      | 25 ++++++++++---------
 clang/unittests/Format/TokenAnnotatorTest.cpp | 16 +++++++++++-
 3 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 4bfb803ebedf7..94bfd4106c480 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -833,11 +833,6 @@ class AnnotatingParser {
           if (Parent && Parent->is(TT_PointerOrReference))
             Parent->overwriteFixedType(TT_BinaryOperator);
         }
-        // An arrow after an ObjC method expression is not a lambda arrow.
-        if (CurrentToken->is(TT_ObjCMethodExpr) && CurrentToken->Next &&
-            CurrentToken->Next->is(TT_LambdaArrow)) {
-          CurrentToken->Next->overwriteFixedType(TT_Unknown);
-        }
         Left->MatchingParen = CurrentToken;
         CurrentToken->MatchingParen = Left;
         // FirstObjCSelectorName is set when a colon is found. This does
diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index 2c9766c9b7bc0..38d0cb3dc0591 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -2268,7 +2268,7 @@ bool UnwrappedLineParser::tryToParseLambda() {
   if (!tryToParseLambdaIntroducer())
     return false;
 
-  bool SeenArrow = false;
+  FormatToken *Arrow = nullptr;
   bool InTemplateParameterList = false;
 
   while (FormatTok->isNot(tok::l_brace)) {
@@ -2343,17 +2343,13 @@ bool UnwrappedLineParser::tryToParseLambda() {
     case tok::ellipsis:
     case tok::kw_true:
     case tok::kw_false:
-      if (SeenArrow || InTemplateParameterList) {
+      if (Arrow || InTemplateParameterList) {
         nextToken();
         break;
       }
       return true;
     case tok::arrow:
-      // This might or might not actually be a lambda arrow (this could be an
-      // ObjC method invocation followed by a dereferencing arrow). We might
-      // reset this back to TT_Unknown in TokenAnnotator.
-      FormatTok->setFinalizedType(TT_LambdaArrow);
-      SeenArrow = true;
+      Arrow = FormatTok;
       nextToken();
       break;
     case tok::kw_requires: {
@@ -2375,6 +2371,9 @@ bool UnwrappedLineParser::tryToParseLambda() {
   FormatTok->setFinalizedType(TT_LambdaLBrace);
   LSquare.setFinalizedType(TT_LambdaLSquare);
 
+  if (Arrow)
+    Arrow->setFinalizedType(TT_LambdaArrow);
+
   NestedLambdas.push_back(Line->SeenDecltypeAuto);
   parseChildBlock();
   assert(!NestedLambdas.empty());
@@ -2388,11 +2387,6 @@ bool UnwrappedLineParser::tryToParseLambdaIntroducer() {
   const FormatToken *LeftSquare = FormatTok;
   nextToken();
   if (Previous) {
-    if (Previous->Tok.getIdentifierInfo() &&
-        !Previous->isOneOf(tok::kw_return, tok::kw_co_await, tok::kw_co_yield,
-                           tok::kw_co_return)) {
-      return false;
-    }
     if (Previous->closesScope()) {
       // Not a potential C-style cast.
       if (Previous->isNot(tok::r_paren))
@@ -2403,6 +2397,13 @@ bool UnwrappedLineParser::tryToParseLambdaIntroducer() {
       if (!BeforeRParen || !BeforeRParen->isOneOf(tok::greater, tok::r_paren))
         return false;
     }
+    if (Previous->is(tok::star))
+      Previous = Previous->Previous;
+    if (Previous && Previous->Tok.getIdentifierInfo() &&
+        !Previous->isOneOf(tok::kw_return, tok::kw_co_await, tok::kw_co_yield,
+                           tok::kw_co_return)) {
+      return false;
+    }
   }
   if (LeftSquare->isCppStructuredBinding(IsCpp))
     return false;
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index 4c43a963632a6..4a8f27f656f1d 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -2237,6 +2237,12 @@ TEST_F(TokenAnnotatorTest, UnderstandsLambdas) {
   ASSERT_EQ(Tokens.size(), 21u) << Tokens;
   EXPECT_TOKEN(Tokens[11], tok::l_square, TT_LambdaLSquare);
   EXPECT_TOKEN(Tokens[13], tok::l_brace, TT_LambdaLBrace);
+
+  Tokens = annotate("SomeFunction({[]() -> int *[] { return {}; }});");
+  ASSERT_EQ(Tokens.size(), 22u) << Tokens;
+  EXPECT_TOKEN(Tokens[3], tok::l_square, TT_LambdaLSquare);
+  EXPECT_TOKEN(Tokens[5], tok::l_paren, TT_LambdaDefinitionLParen);
+  EXPECT_TOKEN(Tokens[10], tok::l_square, TT_ArraySubscriptLSquare);
 }
 
 TEST_F(TokenAnnotatorTest, UnderstandsFunctionAnnotations) {
@@ -4159,7 +4165,15 @@ TEST_F(TokenAnnotatorTest, LineCommentTrailingBackslash) {
   EXPECT_TOKEN(Tokens[1], tok::comment, TT_LineComment);
 }
 
-TEST_F(TokenAnnotatorTest, KeywordedFunctionLikeMacro) {
+TEST_F(TokenAnnotatorTest, ArrowAfterSubscript) {
+  auto Tokens =
+      annotate("return (getStructType()->getElements())[eIdx]->getName();");
+  ASSERT_EQ(Tokens.size(), 19u) << Tokens;
+  // Not TT_LambdaArrow.
+  EXPECT_TOKEN(Tokens[13], tok::arrow, TT_Unknown);
+}
+
+TEST_F(TokenAnnotatorTest, QtProperty) {
   auto Style = getLLVMStyle();
   Style.AllowBreakBeforeQtProperty = true;
 

>From 3499a530af07976e36f1110a4f75d5278d738d5e Mon Sep 17 00:00:00 2001
From: owenca <owenpiano at gmail.com>
Date: Sat, 27 Sep 2025 12:27:19 -0700
Subject: [PATCH 2/3] Update TokenAnnotatorTest.cpp

---
 clang/unittests/Format/TokenAnnotatorTest.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index 4a8f27f656f1d..a5514d56f969b 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -4173,7 +4173,7 @@ TEST_F(TokenAnnotatorTest, ArrowAfterSubscript) {
   EXPECT_TOKEN(Tokens[13], tok::arrow, TT_Unknown);
 }
 
-TEST_F(TokenAnnotatorTest, QtProperty) {
+TEST_F(TokenAnnotatorTest, KeywordedFunctionLikeMacro) {
   auto Style = getLLVMStyle();
   Style.AllowBreakBeforeQtProperty = true;
 

>From f34b8f5913be811a2fba14292b6c1360ebdde1ae Mon Sep 17 00:00:00 2001
From: owenca <owenpiano at gmail.com>
Date: Sat, 27 Sep 2025 20:18:17 -0700
Subject: [PATCH 3/3] Update UnwrappedLineParser.cpp

---
 clang/lib/Format/UnwrappedLineParser.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index 38d0cb3dc0591..6948b3de1e408 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -2396,9 +2396,9 @@ bool UnwrappedLineParser::tryToParseLambdaIntroducer() {
       // and `int (*)()`.
       if (!BeforeRParen || !BeforeRParen->isOneOf(tok::greater, tok::r_paren))
         return false;
+    } else if (Previous->is(tok::star)) {
+      Previous = Previous->getPreviousNonComment();
     }
-    if (Previous->is(tok::star))
-      Previous = Previous->Previous;
     if (Previous && Previous->Tok.getIdentifierInfo() &&
         !Previous->isOneOf(tok::kw_return, tok::kw_co_await, tok::kw_co_yield,
                            tok::kw_co_return)) {



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