clang-format: Understand single-line comments at the end of blocks.

This prevents clang-format from moving/aligning the comment in the
snippet:
  void f() {
    int i; // some comment
    // some unrelated comment
  }

llvm-svn: 225352

2 files changed, 14 insertions, 4 deletions

diff --git a/clang/lib/Format/WhitespaceManager.cpp b/clang/lib/Format/WhitespaceManager.cpp
index a2f599142df..bf1207e59c9 100644
--- a/clang/lib/Format/WhitespaceManager.cpp
+++ b/clang/lib/Format/WhitespaceManager.cpp
@@ -163,15 +163,17 @@ void WhitespaceManager::alignTrailingComments() {
                                   Changes[i - 1].StartOfTokenColumn == 0;
     bool WasAlignedWithStartOfNextLine = false;
     if (Changes[i].NewlinesBefore == 1) { // A comment on its own line.
+      unsigned CommentColumn = SourceMgr.getSpellingColumnNumber(
+          Changes[i].OriginalWhitespaceRange.getEnd());
       for (unsigned j = i + 1; j != e; ++j) {
         if (Changes[j].Kind != tok::comment) { // Skip over comments.
+          unsigned NextColumn = SourceMgr.getSpellingColumnNumber(
+              Changes[j].OriginalWhitespaceRange.getEnd());
           // The start of the next token was previously aligned with the
           // start of this comment.
           WasAlignedWithStartOfNextLine =
-              (SourceMgr.getSpellingColumnNumber(
-                   Changes[i].OriginalWhitespaceRange.getEnd()) ==
-               SourceMgr.getSpellingColumnNumber(
-                   Changes[j].OriginalWhitespaceRange.getEnd()));
+              CommentColumn == NextColumn ||
+              CommentColumn == NextColumn + Style.IndentWidth;
           break;
         }
       }
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index a0f450338b1..fc49bde7140 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -998,6 +998,14 @@ TEST_F(FormatTest, UnderstandsSingleLineComments) {
                    " // first\n"
                    "// at start\n"
                    "otherLine();"));
+  EXPECT_EQ("void f() {\n"
+            "  lineWith(); // comment\n"
+            "  // at start\n"
+            "}",
+            format("void              f() {\n"
+                   "  lineWith(); // comment\n"
+                   "  // at start\n"
+                   "}"));
 
   verifyFormat(
       "#define A                                                  \\\n"