allow --enable-all-error-codes to be countermanded

Author: wyattscarpenter

docs/source/command_line.rst

@@ -808,8 +808,8 @@ of the above sections.
     See :ref:`error-codes` and :ref:`error-codes-optional`
     for more information.
 
-    This flag will override disabled error codes from the
-    :option:`--disable-error-code <mypy --disable-error-code>` flag.
+    (Unlike the other flag for error code enablement, these can be countermanded
+    with :option:`--disable-error-code`.)
 
     Note that future releases of mypy will likely introduce more error codes,
     so the effective result of using this flag will change from release to

docs/source/config_file.rst

@@ -768,7 +768,7 @@ section of the command line docs.
 
     Enables all mypy error codes.
 
-    Note: This option will override disabled error codes from the disable_error_code option.
+    Note: This option will be overridden by disabled error codes from the disable_error_code option.
 
 .. confval:: extra_checks
 

docs/source/error_codes.rst

@@ -51,8 +51,8 @@ to enable or disable specific error codes that don't have a dedicated
 command-line flag or config file setting.
 
 :option:`--enable-all-error-codes <mypy --enable-all-error-codes>` enables
-all optional error codes. (Remember that enabling takes priority over
-disabling, so other --disable-error-code flags will not countermand this.)
+all optional error codes. (Unlike the other flag for error code enablement,
+these can be countermanded with :option:`--disable-error-code <mypy --disable-error-code>`.)
 
 Per-module enabling/disabling error codes
 -----------------------------------------

mypy/main.py

@@ -954,7 +954,10 @@ def add_invertible_flag(
         help="Enable a specific error code",
     )
     strictness_group.add_argument(
-        "--enable-all-error-codes", action="store_true", help="Enable all error codes"
+        "--enable-all-error-codes",
+        action="store_true",
+        help="Enable all error codes. Unlike the other flag for error code enablement,"
+        + " these can be countermanded by --disable-error-code",
     )
 
     error_group = parser.add_argument_group(

mypy/options.py

@@ -452,14 +452,18 @@ def process_error_codes(self, *, error_callback: Callable[[str], Any]) -> None:
             error_callback(f"Invalid error code(s): {', '.join(sorted(invalid_codes))}")
 
         self.disabled_error_codes |= {error_codes[code] for code in disabled_codes}
-        if self.enable_all_error_codes:
-            self.enabled_error_codes = set(error_codes.values())
-        else:
-            self.enabled_error_codes |= {error_codes[code] for code in enabled_codes}
+        self.enabled_error_codes |= {error_codes[code] for code in enabled_codes}
 
         # Enabling an error code always overrides disabling
         self.disabled_error_codes -= self.enabled_error_codes
 
+        # enable_all_error_codes codes can be countermanded by disabled_error_codes, which
+        # can in turn be countermanded by enabled_error_codes. But we've just computed the
+        # latter countermanding, so we can use the set of disabled_error_codes that weren't
+        # countermanded to figure out what to really turn off.
+        if self.enable_all_error_codes:
+            self.enabled_error_codes = set(error_codes.values()) - self.disabled_error_codes
+
     def process_incomplete_features(
         self, *, error_callback: Callable[[str], Any], warning_callback: Callable[[str], Any]
     ) -> None: