[clang] [clang-format] Fix a bug in recognizing trailing comments (PR #206393)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-format

Author: owenca (owenca)

<details>
<summary>Changes</summary>

Test cases are borrowed/adapted from #<!-- -->196760.

Fixes #<!-- -->196663

---
Full diff: https://github.com/llvm/llvm-project/pull/206393.diff


2 Files Affected:

- (modified) clang/lib/Format/WhitespaceManager.cpp (+2) 
- (modified) clang/unittests/Format/FormatTestComments.cpp (+36) 


``````````diff
diff --git a/clang/lib/Format/WhitespaceManager.cpp b/clang/lib/Format/WhitespaceManager.cpp
index 4a72abbfa9ec3..5596532556538 100644
--- a/clang/lib/Format/WhitespaceManager.cpp
+++ b/clang/lib/Format/WhitespaceManager.cpp
@@ -154,6 +154,7 @@ void WhitespaceManager::calculateLineBreakInformation() {
     auto &C = Changes[I];
     auto &P = Changes[I - 1];
     auto &PrevTokLength = P.TokenLength;
+    const auto *PP = I > 1 ? &Changes[I - 2] : nullptr;
     SourceLocation OriginalWhitespaceStart =
         C.OriginalWhitespaceRange.getBegin();
     SourceLocation PreviousOriginalWhitespaceEnd =
@@ -214,6 +215,7 @@ void WhitespaceManager::calculateLineBreakInformation() {
         (C.NewlinesBefore > 0 || C.Tok->is(tok::eof) ||
          (C.IsInsideToken && C.Tok->is(tok::comment))) &&
         P.Tok->is(tok::comment) &&
+        (P.NewlinesBefore == 0 || !PP || PP->IsTrailingComment) &&
         // FIXME: This is a dirty hack. The problem is that
         // BreakableLineCommentSection does comment reflow changes and here is
         // the aligning of trailing comments. Consider the case where we reflow
diff --git a/clang/unittests/Format/FormatTestComments.cpp b/clang/unittests/Format/FormatTestComments.cpp
index 707016096f7d2..d9a9f4c18efec 100644
--- a/clang/unittests/Format/FormatTestComments.cpp
+++ b/clang/unittests/Format/FormatTestComments.cpp
@@ -3060,6 +3060,42 @@ TEST_F(FormatTestComments, AlignTrailingCommentsLeave) {
                "}",
                Style);
 
+  // Move comments along, when it appears, that the indentation changed when a
+  // scope has been added or removed.
+  verifyFormat("void func() {\n"
+               "  int i;\n"
+               "  // comment\n"
+               "  // comment 2\n"
+               "}",
+               "void func() {\n"
+               "    int i;\n"
+               "    // comment\n"
+               "    // comment 2\n"
+               "}",
+               Style);
+
+  verifyFormat("void func() {\n"
+               "  // comment\n"
+               "  // comment 2\n"
+               "  int i;\n"
+               "}",
+               "void func() {\n"
+               "    // comment\n"
+               "    // comment 2\n"
+               "    int i;\n"
+               "}",
+               Style);
+
+  verifyFormat("void func() {\n"
+               "  // non-trailing comment\n"
+               "  int i;\n"
+               "}",
+               "void func() {\n"
+               "     // non-trailing comment\n"
+               "    int i;\n"
+               "}",
+               Style);
+
   Style.AlignEscapedNewlines = FormatStyle::ENAS_Left;
   verifyNoChange("#define FOO    \\\n"
                  "  /* foo(); */ \\\n"

``````````

</details>


https://github.com/llvm/llvm-project/pull/206393