Standardize type comments to always have one space (#2698)

CHANGES.md

@@ -22,6 +22,7 @@
 - Fix crashes involving comments in parenthesised return types or `X | Y` style unions.
   (#4453)
 - Fix skipping Jupyter cells with unknown `%%` magic (#4462)
+- Standardize type comments to always have one space (#4467)
 
 ### Preview style
 

src/black/comments.py

@@ -153,13 +153,20 @@ 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:")
-    ):
+
+    is_type_comment = re.match(r"^\s*type:", content)
+    is_not_type_ignore = re.match(r"^\s*type:(?!\s*ignore\b)", content)
+
+    if content and content[0] == NON_BREAKING_SPACE and not is_type_comment:
         content = " " + content[1:]  # Replace NBSP by a simple space
+    elif is_type_comment and is_not_type_ignore and NON_BREAKING_SPACE not in content:
+        content = content.strip()
+        parts = content.split(":")
+        key = parts[0].strip()  # Remove extra spaces around "type"
+        value = parts[1].strip()  # Remove extra spaces around the value part
+        content = f" {key}: {value}"
     if content and content[0] not in COMMENT_EXCEPTIONS:
         content = " " + content
     return "#" + content

tests/data/cases/type_comment_syntax_error.py

@@ -1,11 +1,54 @@
-def foo(
-    # type: Foo
-    x): pass
+def f(
+    a,  # type: int
+):
+    pass
+
+
+# test type comments
+def f(a, b, c, d, e, f, g, h, i):
+    # type: (int, int, int, int, int, int, int, int, int) -> None
+    pass
+
+
+def f(
+    a,  #  type :   int
+    b,  #    type :  int
+    c,  #type :   int
+    d,  #   type:   int
+    e,  #              type: int    
+    f,  #  type :  int  
+    g,  #type:int
+    h,  # type: int
+    i,  # type: int
+):
+    # type: (...) -> None
+    pass
+
+
 
 # output
+def f(
+    a,  # type: int
+):
+    pass
+
+
+# test type comments
+def f(a, b, c, d, e, f, g, h, i):
+    # type: (int, int, int, int, int, int, int, int, int) -> None
+    pass
+
 
-def foo(
-    # type: Foo
-    x,
+def f(
+    a,  #  type :   int
+    b,  #    type :  int
+    c,  # type :   int
+    d,  # type: int
+    e,  # type: int
+    f,  #  type :  int
+    g,  # type: int
+    h,  # type: int
+    i,  # type: int
 ):
+    # type: (...) -> None
     pass