[PATCH] D118475: [clang-format] Fix misaligned trailing comments in the presence of an empty block comment.

[Marek Kurdej via Phabricator via cfe-commits]

curdeius created this revision.
curdeius added reviewers: MyDeveloperDay, HazardyKnusperkeks, owenpan.
curdeius requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Fixes https://github.com/llvm/llvm-project/issues/53441.

Expected code:

  /**/   //
  int a; //

was before misformatted to:

  /**/     //
  int a; //

Because the "remaining length" (after the starting `/*`) of an empty block 
comment `/**/` was computed to be 0 instead of 2.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118475

Files:
  clang/lib/Format/BreakableToken.cpp
  clang/unittests/Format/FormatTestComments.cpp


Index: clang/unittests/Format/FormatTestComments.cpp
===================================================================
--- clang/unittests/Format/FormatTestComments.cpp
+++ clang/unittests/Format/FormatTestComments.cpp
@@ -2842,6 +2842,12 @@
              "#define FOO_NODELOCAL 4  // Loopback\n\n"
              "} // namespace m\n",
              getLLVMStyleWithColumns(80)));
+
+  // https://llvm.org/PR53441
+  verifyFormat("/* */  //\n"
+               "int a; //\n");
+  verifyFormat("/**/   //\n"
+               "int a; //\n");
 }
 
 TEST_F(FormatTestComments, AlignsBlockCommentDecorations) {
Index: clang/lib/Format/BreakableToken.cpp
===================================================================
--- clang/lib/Format/BreakableToken.cpp
+++ clang/lib/Format/BreakableToken.cpp
@@ -555,7 +555,9 @@
     // We never need a decoration when breaking just the trailing "*/" postfix.
     bool HasRemainingText = Offset < Content[LineIndex].size();
     if (!HasRemainingText) {
-      LineLength -= Decoration.size();
+      bool HasDecoration = Lines[LineIndex].ltrim().startswith(Decoration);
+      if (HasDecoration)
+        LineLength -= Decoration.size();
     }
   }
   return LineLength;



Index: clang/unittests/Format/FormatTestComments.cpp
===================================================================
--- clang/unittests/Format/FormatTestComments.cpp
+++ clang/unittests/Format/FormatTestComments.cpp
@@ -2842,6 +2842,12 @@
              "#define FOO_NODELOCAL 4  // Loopback\n\n"
              "} // namespace m\n",
              getLLVMStyleWithColumns(80)));
+
+  // https://llvm.org/PR53441
+  verifyFormat("/* */  //\n"
+               "int a; //\n");
+  verifyFormat("/**/   //\n"
+               "int a; //\n");
 }
 
 TEST_F(FormatTestComments, AlignsBlockCommentDecorations) {
Index: clang/lib/Format/BreakableToken.cpp
===================================================================
--- clang/lib/Format/BreakableToken.cpp
+++ clang/lib/Format/BreakableToken.cpp
@@ -555,7 +555,9 @@
     // We never need a decoration when breaking just the trailing "*/" postfix.
     bool HasRemainingText = Offset < Content[LineIndex].size();
     if (!HasRemainingText) {
-      LineLength -= Decoration.size();
+      bool HasDecoration = Lines[LineIndex].ltrim().startswith(Decoration);
+      if (HasDecoration)
+        LineLength -= Decoration.size();
     }
   }
   return LineLength;

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