[clang-format] Fix MatchingOpeningBlockLineIndex computation

Summary:
Computed line index must be relative to the current 'parent' node, and
thus use CurrentLines instead of Lines.

Without this, a child line's MatchingOpeningBlockLineIndex is out of
range of the parent's list of line, which can cause crash or unexpected
behavior if this field is used in childs.

Contributed by @Typz!

Reviewers: krasimir, djasper

Reviewed By: krasimir

Subscribers: cfe-commits, klimek

Differential Revision: https://reviews.llvm.org/D32524

llvm-svn: 303353

1 files changed, 3 insertions, 2 deletions

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index 31c66ffb00a..e2762cd42c4 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -429,8 +429,9 @@ void UnwrappedLineParser::parseBlock(bool MustBeDeclaration, bool AddLevel,
     parseParens();
 
   addUnwrappedLine();
-  size_t OpeningLineIndex =
-      Lines.empty() ? (UnwrappedLine::kInvalidIndex) : (Lines.size() - 1);
+  size_t OpeningLineIndex = CurrentLines->empty()
+                                ? (UnwrappedLine::kInvalidIndex)
+                                : (CurrentLines->size() - 1);
 
   ScopedDeclarationState DeclarationState(*Line, DeclarationScopeStack,
                                           MustBeDeclaration);