clang-format: Fix bug introduced in r198871.

We cannot simply change the start column to accomodate for the @ in an
ObjC string literal as that will make clang-format happily violate the
column limit.

Use a different workaround instead. However, a better long-term
solution might be to join the @ and the rest of the literal into a
single token.

llvm-svn: 199198
diff --git a/clang/lib/Format/BreakableToken.cpp b/clang/lib/Format/BreakableToken.cpp
index 8ca97d3..03693c6 100644
--- a/clang/lib/Format/BreakableToken.cpp
+++ b/clang/lib/Format/BreakableToken.cpp
@@ -172,9 +172,16 @@
 void BreakableStringLiteral::insertBreak(unsigned LineIndex,
                                          unsigned TailOffset, Split Split,
                                          WhitespaceManager &Whitespaces) {
+  unsigned LeadingSpaces = StartColumn;
+  // The '@' of an ObjC string literal (@"Test") does not become part of the
+  // string token.
+  // FIXME: It might be a cleaner solution to merge the tokens as a
+  // precomputation step.
+  if (Prefix.startswith("@"))
+    --LeadingSpaces;
   Whitespaces.replaceWhitespaceInToken(
       Tok, Prefix.size() + TailOffset + Split.first, Split.second, Postfix,
-      Prefix, InPPDirective, 1, IndentLevel, StartColumn);
+      Prefix, InPPDirective, 1, IndentLevel, LeadingSpaces);
 }
 
 static StringRef getLineCommentPrefix(StringRef Comment) {