Remove NBSP at the beginning of comments (#2092)

Closes #2091

CHANGES.md

@@ -4,6 +4,8 @@
 
 #### _Black_
 
+- `Black` now cleans up leading non-breaking spaces in comments (#2092)
+
 - `Black` now respects `--skip-string-normalization` when normalizing multiline
   docstring quotes (#1637)
 

src/black/__init__.py

@@ -2709,6 +2709,13 @@ def make_comment(content: str) -> str:
 
     if content[0] == "#":
         content = content[1:]
+    NON_BREAKING_SPACE = " "
+    if (
+        content
+        and content[0] == NON_BREAKING_SPACE
+        and not content.lstrip().startswith("type:")
+    ):
+        content = " " + content[1:]  # Replace NBSP by a simple space
     if content and content[0] not in " !:#'%":
         content = " " + content
     return "#" + content

tests/data/comments7.py

@@ -129,6 +129,8 @@ def test_fails_invalid_post_data(
     ):
         ...
 
+square = Square(4) # type: Optional[Square]
+
 # output
 
 from .config import (
@@ -263,4 +265,7 @@ class C:
     def test_fails_invalid_post_data(
         self, pyramid_config, db_request, post_data, message
     ):
-        ...
+        ...
+
+
+square = Square(4)  # type: Optional[Square]

tests/data/comments_non_breaking_space.py

@@ -0,0 +1,44 @@
+from .config import (  ConfigTypeAttributes,    Int,    Path,    # String,
+    # DEFAULT_TYPE_ATTRIBUTES,
+)
+
+result = 1  # A simple comment
+result = (    1, ) # Another one
+
+result = 1    # type: ignore
+result = 1# This comment is talking about type: ignore
+square = Square(4) # type: Optional[Square]
+
+def function(a:int=42):
+    """ This docstring is already formatted
+       a
+       b
+    """
+    #    There's a NBSP + 3 spaces before
+    #    And 4 spaces on the next line
+    pass
+
+# output
+from .config import (
+    ConfigTypeAttributes,
+    Int,
+    Path,  # String,
+    # DEFAULT_TYPE_ATTRIBUTES,
+)
+
+result = 1  # A simple comment
+result = (1,)  # Another one
+
+result = 1  #  type: ignore
+result = 1  # This comment is talking about type: ignore
+square = Square(4)  #  type: Optional[Square]
+
+
+def function(a: int = 42):
+    """This docstring is already formatted
+    a
+    b
+    """
+    #    There's a NBSP + 3 spaces before
+    #    And 4 spaces on the next line
+    pass

tests/test_format.py

@@ -27,6 +27,7 @@
     "comments5",
     "comments6",
     "comments7",
+    "comments_non_breaking_space",
     "comment_after_escaped_newline",
     "composition",
     "composition_no_trailing_comma",