[clang] 3d99446 - [clang-format] Fix a bug in `DerivePointerAlignment: true` (#150744)

[via cfe-commits]

Author: Owen Pan
Date: 2025-07-28T00:44:12-07:00
New Revision: 3d994468098027f9cf550c78a1c91bb266040f61

URL: https://github.com/llvm/llvm-project/commit/3d994468098027f9cf550c78a1c91bb266040f61
DIFF: https://github.com/llvm/llvm-project/commit/3d994468098027f9cf550c78a1c91bb266040f61.diff

LOG: [clang-format] Fix a bug in `DerivePointerAlignment: true` (#150744)

This effectively reverts a4d4859dc70c046ad928805ddeaf8fa101793394 which
didn't fix the problem that `int*,` was not counted as "Left" alignment.

Fixes #150327

Added: 
    

Modified: 
    clang/lib/Format/Format.cpp
    clang/unittests/Format/FormatTest.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index e6808f7c3bef1..063780721423f 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -2639,32 +2639,44 @@ class Formatter : public TokenAnalyzer {
 
   int countVariableAlignments(const SmallVectorImpl<AnnotatedLine *> &Lines) {
     int AlignmentDiff = 0;
+
     for (const AnnotatedLine *Line : Lines) {
       AlignmentDiff += countVariableAlignments(Line->Children);
-      for (FormatToken *Tok = Line->First; Tok && Tok->Next; Tok = Tok->Next) {
+
+      for (const auto *Tok = Line->getFirstNonComment(); Tok; Tok = Tok->Next) {
         if (Tok->isNot(TT_PointerOrReference))
           continue;
-        // Don't treat space in `void foo() &&` or `void() &&` as evidence.
-        if (const auto *Prev = Tok->getPreviousNonComment()) {
-          if (Prev->is(tok::r_paren) && Prev->MatchingParen) {
-            if (const auto *Func =
-                    Prev->MatchingParen->getPreviousNonComment()) {
-              if (Func->isOneOf(TT_FunctionDeclarationName, TT_StartOfName,
-                                TT_OverloadedOperator) ||
-                  Func->isTypeName(LangOpts)) {
-                continue;
-              }
-            }
-          }
+
+        const auto *Prev = Tok->Previous;
+        const bool PrecededByName = Prev && Prev->Tok.getIdentifierInfo();
+        const bool SpaceBefore = Tok->hasWhitespaceBefore();
+
+        // e.g. `int **`, `int*&`, etc.
+        while (Tok->Next && Tok->Next->is(TT_PointerOrReference))
+          Tok = Tok->Next;
+
+        const auto *Next = Tok->Next;
+        const bool FollowedByName = Next && Next->Tok.getIdentifierInfo();
+        const bool SpaceAfter = Next && Next->hasWhitespaceBefore();
+
+        if ((!PrecededByName && !FollowedByName) ||
+            // e.g. `int * i` or `int*i`
+            (PrecededByName && FollowedByName && SpaceBefore == SpaceAfter)) {
+          continue;
         }
-        bool SpaceBefore = Tok->hasWhitespaceBefore();
-        bool SpaceAfter = Tok->Next->hasWhitespaceBefore();
-        if (SpaceBefore && !SpaceAfter)
+
+        if ((PrecededByName && SpaceBefore) ||
+            (FollowedByName && !SpaceAfter)) {
+          // Right alignment.
           ++AlignmentDiff;
-        if (!SpaceBefore && SpaceAfter)
+        } else if ((PrecededByName && !SpaceBefore) ||
+                   (FollowedByName && SpaceAfter)) {
+          // Left alignment.
           --AlignmentDiff;
+        }
       }
     }
+
     return AlignmentDiff;
   }
 

diff  --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 553d9801e9d87..9c5aa11d6e58f 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -12114,7 +12114,12 @@ TEST_F(FormatTest, UnderstandsFunctionRefQualification) {
            "void b() const &;\n";
   verifyFormat(Prefix + "int *x;", Prefix + "int* x;", DerivePointerAlignment);
 
-  verifyGoogleFormat("MACRO(int*, std::function<void() &&>);");
+  constexpr StringRef Code("MACRO(int*, std::function<void() &&>);");
+  verifyFormat(Code, DerivePointerAlignment);
+
+  auto Style = getGoogleStyle();
+  Style.DerivePointerAlignment = true;
+  verifyFormat(Code, Style);
 }
 
 TEST_F(FormatTest, PointerAlignmentFallback) {