clang-format: Improve handling of raw string literals.

Especially try to keep existing line breaks before raw string literals,
as the code author might have aligned content to it.

Thereby, clang-format now keeps things like:

  parseStyle(R"(
      BasedOnStyle: Google,
      ColumnLimit: 100)");
  parseStyle(
      R"(BasedOnStyle: Google,
         ColumnLimit: 100)");

llvm-svn: 197368

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 37ad7336513..9132ba43770 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -1412,6 +1412,12 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
   } else if (Right.is(tok::l_brace) && (Right.BlockKind == BK_Block)) {
     return Style.BreakBeforeBraces == FormatStyle::BS_Allman ||
            Style.BreakBeforeBraces == FormatStyle::BS_GNU;
+  } else if (Right.is(tok::string_literal) &&
+             Right.TokenText.startswith("R\"")) {
+    // Raw string literals are special wrt. line breaks. The author has made a
+    // deliberate choice and might have aligned the contents of the string
+    // literal accordingly. Thus, we try keep existing line breaks.
+    return Right.NewlinesBefore > 0;
   }
   return false;
 }