Fixes error when splitting block comments.

When trying to fall back to search from the end onwards, we
would still find leading whitespace if the leading whitespace
went on after the end of the line.

llvm-svn: 182886

1 files changed, 10 insertions, 2 deletions

diff --git a/clang/lib/Format/BreakableToken.cpp b/clang/lib/Format/BreakableToken.cpp
index c102f8b1b29..5c3ad9cee2b 100644
--- a/clang/lib/Format/BreakableToken.cpp
+++ b/clang/lib/Format/BreakableToken.cpp
@@ -87,8 +87,16 @@ BreakableToken::Split getCommentSplit(StringRef Text,
   StringRef::size_type SpaceOffset = Text.rfind(' ', MaxSplit);
   if (SpaceOffset == StringRef::npos ||
       // Don't break at leading whitespace.
-      Text.find_last_not_of(' ', SpaceOffset) == StringRef::npos)
-    SpaceOffset = Text.find(' ', MaxSplit);
+      Text.find_last_not_of(' ', SpaceOffset) == StringRef::npos) {
+    // Make sure that we don't break at leading whitespace that
+    // reaches past MaxSplit.
+    StringRef::size_type FirstNonWhitespace = Text.find_first_not_of(" ");
+    if (FirstNonWhitespace == StringRef::npos)
+      // If the comment is only whitespace, we cannot split.
+      return BreakableToken::Split(StringRef::npos, 0);
+    SpaceOffset =
+        Text.find(' ', std::max<unsigned>(MaxSplit, FirstNonWhitespace));
+  }
   if (SpaceOffset != StringRef::npos && SpaceOffset != 0) {
     StringRef BeforeCut = Text.substr(0, SpaceOffset).rtrim();
     StringRef AfterCut = Text.substr(SpaceOffset).ltrim();