Allow per-module error codes

docs/source/error_codes.rst

@@ -69,3 +69,47 @@ which enables the ``no-untyped-def`` error code.
 You can use :option:`--enable-error-code <mypy --enable-error-code>` to
 enable specific error codes that don't have a dedicated command-line
 flag or config file setting.
+
+Per-module enabling/disabling error codes
+-----------------------------------------
+
+You can use :ref:`configuration file <config-file>` sections to enable or
+disable specific error codes only in some modules. For example, this ``mypy.ini``
+config will enable non-annotated empty containers in tests, while keeping
+other parts of code checked in strict mode:
+
+.. code-block:: ini
+
+   [mypy]
+   strict = True
+
+   [mypy-tests.*]
+   allow_untyped_defs = True
+   allow_untyped_calls = True
+   disable_error_code = var-annotated, has-type
+
+Note that per-module enabling/disabling acts as override over the global
+options. So that you don't need to repeat the error code lists for each
+module if you have them in global config section. For example:
+
+.. code-block:: ini
+
+   [mypy]
+   enable_error_code = truthy-bool, ignore-without-code, unused-awaitable
+
+   [mypy-extensions.*]
+   disable_error_code = unused-awaitable
+
+The above config will allow unused awaitables in extension modules, but will
+still keep the other two error codes enabled. The overall logic is following:
+
+* Command line and/or config main section set global error codes
+
+* Individual config sections *adjust* them per glob/module
+
+* Inline ``# mypy: ...`` comments can further *adjust* them for a specific
+  module
+
+So one can e.g. enable some code globally, disable it for all tests in
+the corresponding config section, and then re-enable it with an inline
+comment in some specific test.

mypy/build.py

@@ -235,9 +235,8 @@ def _build(
         options.show_error_end,
         lambda path: read_py_file(path, cached_read),
         options.show_absolute_path,
-        options.enabled_error_codes,
-        options.disabled_error_codes,
         options.many_errors_threshold,
+        options,
     )
     plugin, snapshot = load_plugins(options, errors, stdout, extra_plugins)
 
@@ -2717,7 +2716,7 @@ def module_not_found(
     errors = manager.errors
     save_import_context = errors.import_context()
     errors.set_import_context(caller_state.import_context)
-    errors.set_file(caller_state.xpath, caller_state.id)
+    errors.set_file(caller_state.xpath, caller_state.id, options=caller_state.options)
     if target == "builtins":
         errors.report(
             line, 0, "Cannot find 'builtins' module. Typeshed appears broken!", blocker=True

mypy/checker.py

@@ -453,7 +453,9 @@ def check_first_pass(self) -> None:
         """
         self.recurse_into_functions = True
         with state.strict_optional_set(self.options.strict_optional):
-            self.errors.set_file(self.path, self.tree.fullname, scope=self.tscope)
+            self.errors.set_file(
+                self.path, self.tree.fullname, scope=self.tscope, options=self.options
+            )
             with self.tscope.module_scope(self.tree.fullname):
                 with self.enter_partial_types(), self.binder.top_frame_context():
                     for d in self.tree.defs:
@@ -492,7 +494,9 @@ def check_second_pass(
         with state.strict_optional_set(self.options.strict_optional):
             if not todo and not self.deferred_nodes:
                 return False
-            self.errors.set_file(self.path, self.tree.fullname, scope=self.tscope)
+            self.errors.set_file(
+                self.path, self.tree.fullname, scope=self.tscope, options=self.options
+            )
             with self.tscope.module_scope(self.tree.fullname):
                 self.pass_num += 1
                 if not todo:

mypy/config_parser.py

@@ -8,6 +8,8 @@
 import sys
 from io import StringIO
 
+from mypy.errorcodes import error_codes
+
 if sys.version_info >= (3, 11):
     import tomllib
 else:
@@ -69,6 +71,15 @@ def try_split(v: str | Sequence[str], split_regex: str = "[,]") -> list[str]:
     return [p.strip() for p in v]
 
 
+def validate_codes(codes: list[str]) -> list[str]:
+    invalid_codes = set(codes) - set(error_codes.keys())
+    if invalid_codes:
+        raise argparse.ArgumentTypeError(
+            f"Invalid error code(s): {', '.join(sorted(invalid_codes))}"
+        )
+    return codes
+
+
 def expand_path(path: str) -> str:
     """Expand the user home directory and any environment variables contained within
     the provided path.
@@ -147,8 +158,8 @@ def check_follow_imports(choice: str) -> str:
     "plugins": lambda s: [p.strip() for p in s.split(",")],
     "always_true": lambda s: [p.strip() for p in s.split(",")],
     "always_false": lambda s: [p.strip() for p in s.split(",")],
-    "disable_error_code": lambda s: [p.strip() for p in s.split(",")],
-    "enable_error_code": lambda s: [p.strip() for p in s.split(",")],
+    "disable_error_code": lambda s: validate_codes([p.strip() for p in s.split(",")]),
+    "enable_error_code": lambda s: validate_codes([p.strip() for p in s.split(",")]),
     "package_root": lambda s: [p.strip() for p in s.split(",")],
     "cache_dir": expand_path,
     "python_executable": expand_path,
@@ -168,8 +179,8 @@ def check_follow_imports(choice: str) -> str:
         "plugins": try_split,
         "always_true": try_split,
         "always_false": try_split,
-        "disable_error_code": try_split,
-        "enable_error_code": try_split,
+        "disable_error_code": lambda s: validate_codes(try_split(s)),
+        "enable_error_code": lambda s: validate_codes(try_split(s)),
         "package_root": try_split,
         "exclude": str_or_array_as_list,
     }
@@ -263,6 +274,13 @@ def parse_config_file(
                     file=stderr,
                 )
                 updates = {k: v for k, v in updates.items() if k in PER_MODULE_OPTIONS}
+
+            # These two flags act as per-module overrides, so store the empty defaults.
+            if "disable_error_code" not in updates:
+                updates["disable_error_code"] = []
+            if "enable_error_code" not in updates:
+                updates["enable_error_code"] = []
+
             globs = name[5:]
             for glob in globs.split(","):
                 # For backwards compatibility, replace (back)slashes with dots.

mypy/errors.py

@@ -262,9 +262,8 @@ def __init__(
         show_error_end: bool = False,
         read_source: Callable[[str], list[str] | None] | None = None,
         show_absolute_path: bool = False,
-        enabled_error_codes: set[ErrorCode] | None = None,
-        disabled_error_codes: set[ErrorCode] | None = None,
         many_errors_threshold: int = -1,
+        options: Options | None = None,
     ) -> None:
         self.show_error_context = show_error_context
         self.show_column_numbers = show_column_numbers
@@ -276,9 +275,8 @@ def __init__(
             assert show_column_numbers, "Inconsistent formatting, must be prevented by argparse"
         # We use fscache to read source code when showing snippets.
         self.read_source = read_source
-        self.enabled_error_codes = enabled_error_codes or set()
-        self.disabled_error_codes = disabled_error_codes or set()
         self.many_errors_threshold = many_errors_threshold
+        self.options = options
         self.initialize()
 
     def initialize(self) -> None:
@@ -313,7 +311,13 @@ def simplify_path(self, file: str) -> str:
             file = os.path.normpath(file)
             return remove_path_prefix(file, self.ignore_prefix)
 
-    def set_file(self, file: str, module: str | None, scope: Scope | None = None) -> None:
+    def set_file(
+        self,
+        file: str,
+        module: str | None,
+        scope: Scope | None = None,
+        options: Options | None = None,
+    ) -> None:
         """Set the path and module id of the current file."""
         # The path will be simplified later, in render_messages. That way
         #  * 'file' is always a key that uniquely identifies a source file
@@ -324,6 +328,8 @@ def set_file(self, file: str, module: str | None, scope: Scope | None = None) ->
         self.file = file
         self.target_module = module
         self.scope = scope
+        if options:
+            self.options = options
 
     def set_file_ignored_lines(
         self, file: str, ignored_lines: dict[int, list[str]], ignore_all: bool = False
@@ -586,9 +592,16 @@ def is_ignored_error(self, line: int, info: ErrorInfo, ignores: dict[int, list[s
         return False
 
     def is_error_code_enabled(self, error_code: ErrorCode) -> bool:
-        if error_code in self.disabled_error_codes:
+        if self.options:
+            current_mod_disabled = self.options.disabled_error_codes
+            current_mod_enabled = self.options.enabled_error_codes
+        else:
+            current_mod_disabled = set()
+            current_mod_enabled = set()
+
+        if error_code in current_mod_disabled:
             return False
-        elif error_code in self.enabled_error_codes:
+        elif error_code in current_mod_enabled:
             return True
         else:
             return error_code.default_enabled

mypy/fastparse.py

@@ -263,7 +263,7 @@ def parse(
         raise_on_error = True
     if options is None:
         options = Options()
-    errors.set_file(fnam, module)
+    errors.set_file(fnam, module, options=options)
     is_stub_file = fnam.endswith(".pyi")
     if is_stub_file:
         feature_version = defaults.PYTHON3_VERSION[1]

mypy/options.py

@@ -3,15 +3,13 @@
 import pprint
 import re
 import sys
-from typing import TYPE_CHECKING, Any, Callable, Mapping, Pattern
+from typing import Any, Callable, Dict, Mapping, Pattern
 from typing_extensions import Final
 
 from mypy import defaults
+from mypy.errorcodes import ErrorCode, error_codes
 from mypy.util import get_class_descriptors, replace_object_state
 
-if TYPE_CHECKING:
-    from mypy.errorcodes import ErrorCode
-
 
 class BuildType:
     STANDARD: Final = 0
@@ -27,6 +25,8 @@ class BuildType:
     "always_true",
     "check_untyped_defs",
     "debug_cache",
+    "disable_error_code",
+    "disabled_error_codes",
     "disallow_any_decorated",
     "disallow_any_explicit",
     "disallow_any_expr",
@@ -37,6 +37,8 @@ class BuildType:
     "disallow_untyped_calls",
     "disallow_untyped_decorators",
     "disallow_untyped_defs",
+    "enable_error_code",
+    "enabled_error_codes",
     "follow_imports",
     "follow_imports_for_stubs",
     "ignore_errors",
@@ -347,6 +349,20 @@ def apply_changes(self, changes: dict[str, object]) -> Options:
             # This is the only option for which a per-module and a global
             # option sometimes beheave differently.
             new_options.ignore_missing_imports_per_module = True
+
+        # These two act as overrides, so apply them when cloning.
+        # Similar to global codes enabling overrides disabling, so we start from latter.
+        new_options.disabled_error_codes = self.disabled_error_codes.copy()
+        new_options.enabled_error_codes = self.enabled_error_codes.copy()
+        for code_str in new_options.disable_error_code:
+            code = error_codes[code_str]
+            new_options.disabled_error_codes.add(code)
+            new_options.enabled_error_codes.discard(code)
+        for code_str in new_options.enable_error_code:
+            code = error_codes[code_str]
+            new_options.enabled_error_codes.add(code)
+            new_options.disabled_error_codes.discard(code)
+
         return new_options
 
     def build_per_module_cache(self) -> None:
@@ -446,4 +462,10 @@ def compile_glob(self, s: str) -> Pattern[str]:
         return re.compile(expr + "\\Z")
 
     def select_options_affecting_cache(self) -> Mapping[str, object]:
-        return {opt: getattr(self, opt) for opt in OPTIONS_AFFECTING_CACHE}
+        result: Dict[str, object] = {}
+        for opt in OPTIONS_AFFECTING_CACHE:
+            val = getattr(self, opt)
+            if isinstance(val, set):
+                val = sorted(val)
+            result[opt] = val
+        return result

mypy/semanal.py

@@ -732,7 +732,7 @@ def file_context(
         """
         scope = self.scope
         self.options = options
-        self.errors.set_file(file_node.path, file_node.fullname, scope=scope)
+        self.errors.set_file(file_node.path, file_node.fullname, scope=scope, options=options)
         self.cur_mod_node = file_node
         self.cur_mod_id = file_node.fullname
         with scope.module_scope(self.cur_mod_id):

mypy/semanal_typeargs.py

@@ -46,7 +46,7 @@ def __init__(self, errors: Errors, options: Options, is_typeshed_file: bool) ->
         self.seen_aliases: set[TypeAliasType] = set()
 
     def visit_mypy_file(self, o: MypyFile) -> None:
-        self.errors.set_file(o.path, o.fullname, scope=self.scope)
+        self.errors.set_file(o.path, o.fullname, scope=self.scope, options=self.options)
         with self.scope.module_scope(o.fullname):
             super().visit_mypy_file(o)
 

test-data/unit/check-flags.test

@@ -2053,3 +2053,41 @@ def f(x):
 y = 1
 f(reveal_type(y)) # E: Call to untyped function "f" in typed context \
                   # N: Revealed type is "builtins.int"
+
+[case testPerModuleErrorCodes]
+# flags: --config-file tmp/mypy.ini
+import tests.foo
+import bar
+[file bar.py]
+x = []  # E: Need type annotation for "x" (hint: "x: List[<type>] = ...")
+[file tests/__init__.py]
+[file tests/foo.py]
+x = []  # OK
+[file mypy.ini]
+\[mypy]
+strict = True
+
+\[mypy-tests.*]
+allow_untyped_defs = True
+allow_untyped_calls = True
+disable_error_code = var-annotated
+
+[case testPerModuleErrorCodesOverride]
+# flags: --config-file tmp/mypy.ini
+import tests.foo
+import bar
+[file bar.py]
+def foo() -> int: ...
+if foo: ...  # E: Function "Callable[[], int]" could always be true in boolean context
+42 + "no"  # type: ignore  # E: "type: ignore" comment without error code (consider "type: ignore[operator]" instead)
+[file tests/__init__.py]
+[file tests/foo.py]
+def foo() -> int: ...
+if foo: ...  # E: Function "Callable[[], int]" could always be true in boolean context
+42 + "no"  # type: ignore
+[file mypy.ini]
+\[mypy]
+enable_error_code = ignore-without-code, truthy-bool
+
+\[mypy-tests.*]
+disable_error_code = ignore-without-code

test-data/unit/check-inline-config.test

@@ -162,3 +162,12 @@ main:1: error: Unrecognized option: skip_file = True
 # mypy: strict
 [out]
 main:1: error: Setting "strict" not supported in inline configuration: specify it in a configuration file instead, or set individual inline flags (see "mypy -h" for the list of flags enabled in strict mode)
+
+[case testInlineErrorCodes]
+# flags: --strict-optional
+# mypy: enable-error-code="ignore-without-code,truthy-bool"
+
+def foo() -> int: ...
+if foo: ...  # E: Function "Callable[[], int]" could always be true in boolean context
+
+42 + "no"  # type: ignore  # E: "type: ignore" comment without error code (consider "type: ignore[operator]" instead)