Avoid unstable formatting when comment follows escaped newline. (#839). Fixes #767.

[etc/vim.git] / black.py

diff --git a/black.py b/black.py
index 18d60c02d6b48cc918a5978a7e2124b1f6f160c3..1978fd52ec91969e226908ebb566d18f422a3ab7 100644 (file)
--- a/black.py
+++ b/black.py
@@ -2145,15 +2145,21 @@ def list_comments(prefix: str, *, is_endmarker: bool) -> List[ProtoComment]:
 
     consumed = 0
     nlines = 0
+    ignored_lines = 0
     for index, line in enumerate(prefix.split("\n")):
         consumed += len(line) + 1  # adding the length of the split '\n'
         line = line.lstrip()
         if not line:
             nlines += 1
         if not line.startswith("#"):
+            # Escaped newlines outside of a comment are not really newlines at
+            # all. We treat a single-line comment following an escaped newline
+            # as a simple trailing comment.
+            if line.endswith("\\"):
+                ignored_lines += 1
             continue
 
-        if index == 0 and not is_endmarker:
+        if index == ignored_lines and not is_endmarker:
             comment_type = token.COMMENT  # simple trailing comment
         else:
             comment_type = STANDALONE_COMMENT