[clang-format] Add new style option IndentGotoLabels

Summary:
This option determines whether goto labels are indented according to scope. Setting this option to false causes goto labels to be flushed to the left.
This is mostly copied from [[ http://lists.llvm.org/pipermail/cfe-dev/2015-September/045014.html | this patch ]] submitted by Christian Neukirchen that didn't make its way into trunk.

```
     true:                                  false:
     int f() {                      vs.     int f() {
       if (foo()) {                           if (foo()) {
       label1:                              label1:
         bar();                                 bar();
       }                                      }
     label2:                                label2:
       return 1;                              return 1;
     }                                      }
```

Reviewers: klimek, MyDeveloperDay

Reviewed By: MyDeveloperDay

Subscribers: cfe-commits

Tags: #clang, #clang-tools-extra

Patch by: tetsuo-cpp

Differential Revision: https://reviews.llvm.org/D67037

llvm-svn: 371719

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index bbb243dd329..e552a055b04 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -1351,7 +1351,7 @@ void UnwrappedLineParser::parseStructuralElement() {
           (TokenCount == 2 && Line->Tokens.front().Tok->is(tok::comment))) {
         if (FormatTok->Tok.is(tok::colon) && !Line->MustBeDeclaration) {
           Line->Tokens.begin()->Tok->MustBreakBefore = true;
-          parseLabel();
+          parseLabel(!Style.IndentGotoLabels);
           return;
         }
         // Recognize function-like macro usages without trailing semicolon as
@@ -1970,11 +1970,13 @@ void UnwrappedLineParser::parseDoWhile() {
   parseStructuralElement();
 }
 
-void UnwrappedLineParser::parseLabel() {
+void UnwrappedLineParser::parseLabel(bool LeftAlignLabel) {
   nextToken();
   unsigned OldLineLevel = Line->Level;
   if (Line->Level > 1 || (!Line->InPPDirective && Line->Level > 0))
     --Line->Level;
+  if (LeftAlignLabel)
+    Line->Level = 0;
   if (CommentsBeforeNextToken.empty() && FormatTok->Tok.is(tok::l_brace)) {
     CompoundStatementIndenter Indenter(this, Line->Level,
                                        Style.BraceWrapping.AfterCaseLabel,