Standardize type comments

CHANGES.md

@@ -17,6 +17,7 @@
   `case Foo(bar=baz as quux)` (#2749)
 - No longer color diff headers white as it's unreadable in light themed terminals
   (#2691)
+- Standardize type comments to always have one space (#2698)
 - Tuple unpacking on `return` and `yield` constructs now implies 3.8+ (#2700)
 - Unparenthesized tuples on annotated assignments (e.g
   `values: Tuple[int, ...] = 1, 2, 3`) now implies 3.8+ (#2708)

src/black/comments.py

@@ -123,6 +123,11 @@ def make_comment(content: str) -> str:
         and not content.lstrip().startswith("type:")
     ):
         content = " " + content[1:]  # Replace NBSP by a simple space
+    elif NON_BREAKING_SPACE not in content:
+        type_comment = re.match(r"\s*type\s*:\s*(.*)", content)
+        if type_comment:
+            content = "type: " + type_comment.group(1)
+
     if content and content[0] not in " !:#'%":
         content = " " + content
     return "#" + content
@@ -271,7 +276,7 @@ def contains_pragma_comment(comment_list: List[Leaf]) -> bool:
         pylint).
     """
     for comment in comment_list:
-        if comment.value.startswith(("# type:", "# noqa", "# pylint:")):
+        if re.match(r"#\s*(type\s*:|pylint\s*:|noqa\s*)", comment.value):
             return True
 
     return False

src/black/nodes.py

@@ -3,6 +3,7 @@
 """
 
 import sys
+import re
 from typing import (
     Collection,
     Generic,
@@ -803,7 +804,11 @@ def is_type_comment(leaf: Leaf, suffix: str = "") -> bool:
     Only returns true for type comments for now."""
     t = leaf.type
     v = leaf.value
-    return t in {token.COMMENT, STANDALONE_COMMENT} and v.startswith("# type:" + suffix)
+    type_comment_regex = r"#\s*type\s*:\s*" + suffix
+    return (
+        t in {token.COMMENT, STANDALONE_COMMENT}
+        and re.match(type_comment_regex, v) is not None
+    )
 
 
 def wrap_in_parentheses(parent: Node, child: LN, *, visible: bool = True) -> None:

tests/data/comments7.py

@@ -50,15 +50,15 @@ def func():
         0.0789,
         0.0123,
         0.0789,
-        a[-1],  # type: ignore
+        a[-1],  # type:   ignore
     )
     c = call(
         0.0123,
         0.0456,
         0.0789,
         0.0123,
         0.0789,
-        a[-1]  # type: ignore
+        a[-1]  #   type:ignore
     )
     c = call(
         0.0123,
@@ -70,7 +70,7 @@ def func():
         0.0123,
         0.0456,
         0.0789,
-        a[-1]  # type: ignore
+        a[-1]  #  type   :    ignore
     )
 
     # The type: ignore exception only applies to line length, not

tests/data/long_strings.py

@@ -97,6 +97,8 @@
 
 pragma_comment_string2 = "Lines which end with an inline pragma comment of the form `# <pragma>: <...>` should be left alone."  # noqa
 
+pragma_comment_string3 = "Lines which end with an inline pragma comment of the form `# <pragma>: <...>` should be left alone."  #   noqa
+
 """This is a really really really long triple quote string and it should not be touched."""
 
 triple_quote_string = """This is a really really really long triple quote string assignment and it should not be touched."""
@@ -463,6 +465,8 @@ def foo():
 
 pragma_comment_string2 = "Lines which end with an inline pragma comment of the form `# <pragma>: <...>` should be left alone."  # noqa
 
+pragma_comment_string3 = "Lines which end with an inline pragma comment of the form `# <pragma>: <...>` should be left alone."  #   noqa
+
 """This is a really really really long triple quote string and it should not be touched."""
 
 triple_quote_string = """This is a really really really long triple quote string assignment and it should not be touched."""