[clang-format] Fix shortening blocks in macros causing merged next line

Summary:
This patch addresses bug 36002, where a combination of options causes the line
following a short block in macro to be merged with that macro.

Reviewers: bkramer

Reviewed By: bkramer

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D42298

llvm-svn: 322954

1 files changed, 9 insertions, 3 deletions

diff --git a/clang/lib/Format/UnwrappedLineFormatter.cpp b/clang/lib/Format/UnwrappedLineFormatter.cpp
index 60dc1a7169d..253f89da9d1 100644
--- a/clang/lib/Format/UnwrappedLineFormatter.cpp
+++ b/clang/lib/Format/UnwrappedLineFormatter.cpp
@@ -304,9 +304,15 @@ private:
     if (TheLine->First->is(tok::l_brace) && TheLine->First == TheLine->Last &&
         I != AnnotatedLines.begin() &&
         I[-1]->First->isOneOf(tok::kw_if, tok::kw_while, tok::kw_for)) {
-      return Style.AllowShortBlocksOnASingleLine
-                 ? tryMergeSimpleBlock(I - 1, E, Limit)
-                 : 0;
+      unsigned MergedLines = 0;
+      if (Style.AllowShortBlocksOnASingleLine) {
+        MergedLines = tryMergeSimpleBlock(I - 1, E, Limit);
+        // If we managed to merge the block, discard the first merged line
+        // since we are merging starting from I.
+        if (MergedLines > 0)
+          --MergedLines;
+      }
+      return MergedLines;
     }
     // Try to merge a block with left brace wrapped that wasn't yet covered
     if (TheLine->Last->is(tok::l_brace)) {