Ignore # fmt: off as inline comment

Black cannot currently support this form due to its generator-based nature.
This is mostly a problem for existing `# yapf: disable` usage as trailing
comment.

Fixes #95

README.md

@@ -426,6 +426,9 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 * fixed 18.3a4 regression: don't crash and burn on empty lines with
   trailing whitespace (#80)
 
+* fixed 18.3a4 regression: `# yapf: disable` usage as trailing comment
+  would cause Black to not emit the rest of the file (#95)
+
 * when CTRL+C is pressed while formatting many files, Black no longer
   freaks out with a flurry of asyncio-related exceptions
 

black.py

@@ -1134,6 +1134,10 @@ def visit_unformatted(self, node: LN) -> Iterator[Line]:
                 yield from self.line()
                 yield from self.visit(node)
 
+            if node.type == token.ENDMARKER:
+                # somebody decided not to put a final `# fmt: on`
+                yield from self.line()
+
     def __attrs_post_init__(self) -> None:
         """You are in a twisty little maze of passages."""
         v = self.visit_stmt
@@ -1537,6 +1541,11 @@ def generate_comments(leaf: Leaf) -> Iterator[Leaf]:
             raise FormatOn(consumed)
 
         if comment in {"# fmt: off", "# yapf: disable"}:
+            if comment_type == STANDALONE_COMMENT:
+                raise FormatOff(consumed)
+
+            prev = preceding_leaf(leaf)
+            if not prev or prev.type in WHITESPACE:  # standalone comment in disguise
                 raise FormatOff(consumed)
 
         nlines = 0

tests/fmtonoff.py

@@ -71,6 +71,18 @@ def long_lines():
         $
         """, re.MULTILINE | re.VERBOSE
     )
+def single_literal_yapf_disable():
+    """Black does not support this."""
+    BAZ = {
+        (1, 2, 3, 4),
+        (5, 6, 7, 8),
+        (9, 10, 11, 12),
+    }  # yapf: disable
+# fmt: off
+# No formatting to the end of the file
+l=[1,2,3]
+d={'a':1,
+   'b':2}
 
 # output
 
@@ -175,3 +187,15 @@ def long_lines():
         """,
         re.MULTILINE | re.VERBOSE,
     )
+
+
+def single_literal_yapf_disable():
+    """Black does not support this."""
+    BAZ = {(1, 2, 3, 4), (5, 6, 7, 8), (9, 10, 11, 12)}  # yapf: disable
+
+
+# fmt: off
+# No formatting to the end of the file
+l=[1,2,3]
+d={'a':1,
+   'b':2}