clang-format: Fix clang-format-diff.py according to diff specification.

Patch by Alp Toker. Many thanks!

Original descriptions:
clang-format-diff incorrectly modifies unchanged lines due to an error
in diff parsing.

The unified diff format has a default line change count of 1, and 0 may
be specified to indicate that no lines have been added. This patch
updates the parser to accurately reflect the diff specification.

This also has the benefit of stabilising the operation so it will
produce the same output when run multiple times on the same changeset,
which was previously not the case.

No tests added because this script is not currently tested (though we
should look into that!)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191820 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/tools/clang-format/clang-format-diff.py b/tools/clang-format/clang-format-diff.py
index 7c141785a3256137f257653297c624845f4f7910..90723d217b8915eae0782aae773143e8db6585d8 100755 (executable)
--- a/tools/clang-format/clang-format-diff.py
+++ b/tools/clang-format/clang-format-diff.py
@@ -60,9 +60,12 @@ def main():
     match = re.search('^@@.*\+(\d+)(,(\d+))?', line)
     if match:
       start_line = int(match.group(1))
-      end_line = start_line
+      line_count = 1
       if match.group(3):
-        end_line = start_line + int(match.group(3))
+        line_count = int(match.group(3))
+      if line_count == 0:
+        continue
+      end_line = start_line + line_count - 1;
       lines_by_file.setdefault(filename, []).extend(
           ['-lines', str(start_line) + ':' + str(end_line)])