Support FIXME names for unknown types in dmypy suggest (#7679)

This PR adds an option to `dmypy suggest` to replace `Any` in suggested signatures with a dummy name like `FIXME` or `UNKNOWN`. The main question here is whether we should replace only the top-level `Any`s , or also nested one. I am leaning towards the former, but this is not a strong opinion.

mypy/dmypy/client.py

@@ -114,6 +114,8 @@ def __init__(self, prog: str) -> None:
                help="Try using unicode wherever str is inferred")
 p.add_argument('--callsites', action='store_true',
                help="Find callsites instead of suggesting a type")
+p.add_argument('--use-fixme', metavar='NAME', type=str,
+               help="A dummy name to use instead of Any for types that can't be inferred")
 
 hang_parser = p = subparsers.add_parser('hang', help="Hang for 100 seconds")
 
@@ -367,7 +369,8 @@ def do_suggest(args: argparse.Namespace) -> None:
     """
     response = request(args.status_file, 'suggest', function=args.function,
                        json=args.json, callsites=args.callsites, no_errors=args.no_errors,
-                       no_any=args.no_any, flex_any=args.flex_any, try_text=args.try_text)
+                       no_any=args.no_any, flex_any=args.flex_any, try_text=args.try_text,
+                       use_fixme=args.use_fixme)
     check_output(response, verbose=False, junit_xml=None, perf_stats_file=None)
 
 

mypy/semanal.py

@@ -50,7 +50,7 @@
 from contextlib import contextmanager
 
 from typing import (
-    List, Dict, Set, Tuple, cast, TypeVar, Union, Optional, Callable, Iterator, Iterable,
+    List, Dict, Set, Tuple, cast, TypeVar, Union, Optional, Callable, Iterator, Iterable
 )
 from typing_extensions import Final
 

mypy/suggestions.py

@@ -160,7 +160,8 @@ def __init__(self, fgmanager: FineGrainedBuildManager,
                  no_errors: bool = False,
                  no_any: bool = False,
                  try_text: bool = False,
-                 flex_any: Optional[float] = None) -> None:
+                 flex_any: Optional[float] = None,
+                 use_fixme: Optional[str] = None) -> None:
         self.fgmanager = fgmanager
         self.manager = fgmanager.manager
         self.plugin = self.manager.plugin
@@ -175,6 +176,7 @@ def __init__(self, fgmanager: FineGrainedBuildManager,
             self.flex_any = 1.0
 
         self.max_guesses = 16
+        self.use_fixme = use_fixme
 
     def suggest(self, function: str) -> str:
         """Suggest an inferred type for function."""
@@ -592,6 +594,8 @@ def format_signature(self, sig: PyAnnotateSignature) -> str:
         )
 
     def format_type(self, cur_module: Optional[str], typ: Type) -> str:
+        if self.use_fixme and isinstance(get_proper_type(typ), AnyType):
+            return self.use_fixme
         return typ.accept(TypeFormatter(cur_module, self.graph))
 
     def score_type(self, t: Type, arg_pos: bool) -> int:

mypy/test/testfinegrained.py

@@ -281,10 +281,12 @@ def maybe_suggest(self, step: int, server: Server, src: str, tmp_dir: str) -> Li
             try_text = '--try-text' in flags
             m = re.match('--flex-any=([0-9.]+)', flags)
             flex_any = float(m.group(1)) if m else None
+            m = re.match(r'--use-fixme=(\w+)', flags)
+            use_fixme = m.group(1) if m else None
             res = cast(Dict[str, Any],
                        server.cmd_suggest(
                            target.strip(), json=json, no_any=no_any, no_errors=no_errors,
-                           try_text=try_text, flex_any=flex_any,
+                           try_text=try_text, flex_any=flex_any, use_fixme=use_fixme,
                            callsites=callsites))
             val = res['error'] if 'error' in res else res['out'] + res['err']
             if json:

test-data/unit/fine-grained-suggest.test

@@ -733,3 +733,38 @@ func('test')
 [out]
 (str) -> int
 ==
+
+[case testSuggestUseFixmeBasic]
+# suggest: --use-fixme=UNKNOWN foo.foo
+# suggest: --use-fixme=UNKNOWN foo.bar
+[file foo.py]
+
+def foo():
+    return g()
+
+def bar(x):
+    return None
+
+def g(): ...
+x = bar(g())
+[out]
+() -> UNKNOWN
+(UNKNOWN) -> None
+==
+
+[case testSuggestUseFixmeNoNested]
+# suggest: --use-fixme=UNKNOWN foo.foo
+[file foo.py]
+from typing import List, Any
+
+def foo(x, y):
+    return x, y
+
+def f() -> List[Any]: ...
+def g(): ...
+
+z = foo(f(), g())
+[builtins fixtures/isinstancelist.pyi]
+[out]
+(foo.List[Any], UNKNOWN) -> Tuple[foo.List[Any], Any]
+==