Add option to selectively disable --disallow-untyped-calls (#15845)

Fixes #10757 

It is surprisingly one of the most upvoted issues. Also it looks quite
easy to implement, so why not. Note I also try to improve docs for
per-module logic for `disallow_untyped_calls`, as there is currently
some confusion.

---------

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@hopper.com>

Author: ilevkivskyi

docs/source/command_line.rst

@@ -350,6 +350,34 @@ definitions or calls.
     This flag reports an error whenever a function with type annotations
     calls a function defined without annotations.
 
+.. option:: --untyped-calls-exclude
+
+    This flag allows to selectively disable :option:`--disallow-untyped-calls`
+    for functions and methods defined in specific packages, modules, or classes.
+    Note that each exclude entry acts as a prefix. For example (assuming there
+    are no type annotations for ``third_party_lib`` available):
+
+    .. code-block:: python
+
+        # mypy --disallow-untyped-calls
+        #      --untyped-calls-exclude=third_party_lib.module_a
+        #      --untyped-calls-exclude=foo.A
+        from third_party_lib.module_a import some_func
+        from third_party_lib.module_b import other_func
+        import foo
+
+        some_func()  # OK, function comes from module `third_party_lib.module_a`
+        other_func()  # E: Call to untyped function "other_func" in typed context
+
+        foo.A().meth()  # OK, method was defined in class `foo.A`
+        foo.B().meth()  # E: Call to untyped function "meth" in typed context
+
+        # file foo.py
+        class A:
+            def meth(self): pass
+        class B:
+            def meth(self): pass
+
 .. option:: --disallow-untyped-defs
 
     This flag reports an error whenever it encounters a function definition

docs/source/config_file.rst

@@ -490,7 +490,38 @@ section of the command line docs.
     :default: False
 
     Disallows calling functions without type annotations from functions with type
-    annotations.
+    annotations. Note that when used in per-module options, it enables/disables
+    this check **inside** the module(s) specified, not for functions that come
+    from that module(s), for example config like this:
+
+    .. code-block:: ini
+
+        [mypy]
+        disallow_untyped_calls = True
+
+        [mypy-some.library.*]
+        disallow_untyped_calls = False
+
+    will disable this check inside ``some.library``, not for your code that
+    imports ``some.library``. If you want to selectively disable this check for
+    all your code that imports ``some.library`` you should instead use
+    :confval:`untyped_calls_exclude`, for example:
+
+    .. code-block:: ini
+
+        [mypy]
+        disallow_untyped_calls = True
+        untyped_calls_exclude = some.library
+
+.. confval:: untyped_calls_exclude
+
+    :type: comma-separated list of strings
+
+    Selectively excludes functions and methods defined in specific packages,
+    modules, and classes from action of :confval:`disallow_untyped_calls`.
+    This also applies to all submodules of packages (i.e. everything inside
+    a given prefix). Note, this option does not support per-file configuration,
+    the exclusions list is defined globally for all your code.
 
 .. confval:: disallow_untyped_defs
 

mypy/checkexpr.py

@@ -529,13 +529,6 @@ def visit_call_expr_inner(self, e: CallExpr, allow_none_return: bool = False) ->
         callee_type = get_proper_type(
             self.accept(e.callee, type_context, always_allow_any=True, is_callee=True)
         )
-        if (
-            self.chk.options.disallow_untyped_calls
-            and self.chk.in_checked_function()
-            and isinstance(callee_type, CallableType)
-            and callee_type.implicit
-        ):
-            self.msg.untyped_function_call(callee_type, e)
 
         # Figure out the full name of the callee for plugin lookup.
         object_type = None
@@ -561,6 +554,22 @@ def visit_call_expr_inner(self, e: CallExpr, allow_none_return: bool = False) ->
             ):
                 member = e.callee.name
                 object_type = self.chk.lookup_type(e.callee.expr)
+
+        if (
+            self.chk.options.disallow_untyped_calls
+            and self.chk.in_checked_function()
+            and isinstance(callee_type, CallableType)
+            and callee_type.implicit
+        ):
+            if fullname is None and member is not None:
+                assert object_type is not None
+                fullname = self.method_fullname(object_type, member)
+            if not fullname or not any(
+                fullname == p or fullname.startswith(f"{p}.")
+                for p in self.chk.options.untyped_calls_exclude
+            ):
+                self.msg.untyped_function_call(callee_type, e)
+
         ret_type = self.check_call_expr_with_callee_type(
             callee_type, e, fullname, object_type, member
         )

mypy/config_parser.py

@@ -81,6 +81,20 @@ def validate_codes(codes: list[str]) -> list[str]:
     return codes
 
 
+def validate_package_allow_list(allow_list: list[str]) -> list[str]:
+    for p in allow_list:
+        msg = f"Invalid allow list entry: {p}"
+        if "*" in p:
+            raise argparse.ArgumentTypeError(
+                f"{msg} (entries are already prefixes so must not contain *)"
+            )
+        if "\\" in p or "/" in p:
+            raise argparse.ArgumentTypeError(
+                f"{msg} (entries must be packages like foo.bar not directories or files)"
+            )
+    return allow_list
+
+
 def expand_path(path: str) -> str:
     """Expand the user home directory and any environment variables contained within
     the provided path.
@@ -164,6 +178,9 @@ def split_commas(value: str) -> list[str]:
     "plugins": lambda s: [p.strip() for p in split_commas(s)],
     "always_true": lambda s: [p.strip() for p in split_commas(s)],
     "always_false": lambda s: [p.strip() for p in split_commas(s)],
+    "untyped_calls_exclude": lambda s: validate_package_allow_list(
+        [p.strip() for p in split_commas(s)]
+    ),
     "enable_incomplete_feature": lambda s: [p.strip() for p in split_commas(s)],
     "disable_error_code": lambda s: validate_codes([p.strip() for p in split_commas(s)]),
     "enable_error_code": lambda s: validate_codes([p.strip() for p in split_commas(s)]),
@@ -187,6 +204,7 @@ def split_commas(value: str) -> list[str]:
         "plugins": try_split,
         "always_true": try_split,
         "always_false": try_split,
+        "untyped_calls_exclude": lambda s: validate_package_allow_list(try_split(s)),
         "enable_incomplete_feature": try_split,
         "disable_error_code": lambda s: validate_codes(try_split(s)),
         "enable_error_code": lambda s: validate_codes(try_split(s)),

mypy/main.py

@@ -11,7 +11,12 @@
 from typing import IO, Any, Final, NoReturn, Sequence, TextIO
 
 from mypy import build, defaults, state, util
-from mypy.config_parser import get_config_module_names, parse_config_file, parse_version
+from mypy.config_parser import (
+    get_config_module_names,
+    parse_config_file,
+    parse_version,
+    validate_package_allow_list,
+)
 from mypy.errorcodes import error_codes
 from mypy.errors import CompileError
 from mypy.find_sources import InvalidSourceList, create_source_list
@@ -675,6 +680,14 @@ def add_invertible_flag(
         " from functions with type annotations",
         group=untyped_group,
     )
+    untyped_group.add_argument(
+        "--untyped-calls-exclude",
+        metavar="MODULE",
+        action="append",
+        default=[],
+        help="Disable --disallow-untyped-calls for functions/methods coming"
+        " from specific package, module, or class",
+    )
     add_invertible_flag(
         "--disallow-untyped-defs",
         default=False,
@@ -1307,6 +1320,8 @@ def set_strict_flags() -> None:
             % ", ".join(sorted(overlap))
         )
 
+    validate_package_allow_list(options.untyped_calls_exclude)
+
     # Process `--enable-error-code` and `--disable-error-code` flags
     disabled_codes = set(options.disable_error_code)
     enabled_codes = set(options.enable_error_code)

mypy/options.py

@@ -136,6 +136,10 @@ def __init__(self) -> None:
         # Disallow calling untyped functions from typed ones
         self.disallow_untyped_calls = False
 
+        # Always allow untyped calls for function coming from modules/packages
+        # in this list (each item effectively acts as a prefix match)
+        self.untyped_calls_exclude: list[str] = []
+
         # Disallow defining untyped (or incompletely typed) functions
         self.disallow_untyped_defs = False
 

test-data/unit/check-flags.test

@@ -2077,6 +2077,61 @@ y = 1
 f(reveal_type(y)) # E: Call to untyped function "f" in typed context \
                   # N: Revealed type is "builtins.int"
 
+[case testDisallowUntypedCallsAllowListFlags]
+# flags: --disallow-untyped-calls  --untyped-calls-exclude=foo --untyped-calls-exclude=bar.A
+from foo import test_foo
+from bar import A, B
+from baz import test_baz
+from foobar import bad
+
+test_foo(42)  # OK
+test_baz(42)  # E: Call to untyped function "test_baz" in typed context
+bad(42)  # E: Call to untyped function "bad" in typed context
+
+a: A
+b: B
+a.meth()  # OK
+b.meth()  # E: Call to untyped function "meth" in typed context
+[file foo.py]
+def test_foo(x): pass
+[file foobar.py]
+def bad(x): pass
+[file bar.py]
+class A:
+    def meth(self): pass
+class B:
+    def meth(self): pass
+[file baz.py]
+def test_baz(x): pass
+
+[case testDisallowUntypedCallsAllowListConfig]
+# flags: --config-file tmp/mypy.ini
+from foo import test_foo
+from bar import A, B
+from baz import test_baz
+
+test_foo(42)  # OK
+test_baz(42)  # E: Call to untyped function "test_baz" in typed context
+
+a: A
+b: B
+a.meth()  # OK
+b.meth()  # E: Call to untyped function "meth" in typed context
+[file foo.py]
+def test_foo(x): pass
+[file bar.py]
+class A:
+    def meth(self): pass
+class B:
+    def meth(self): pass
+[file baz.py]
+def test_baz(x): pass
+
+[file mypy.ini]
+\[mypy]
+disallow_untyped_calls = True
+untyped_calls_exclude = foo, bar.A
+
 [case testPerModuleErrorCodes]
 # flags: --config-file tmp/mypy.ini
 import tests.foo