Show error codes by default (#13542)

Part of the effort to nudge users into using specific type ignores. See
#13541

This PR enables `show-error-codes` by default. Without knowing the code,
users will always choose to use a bare `type: ignore` instead.

docs/source/command_line.rst

@@ -691,9 +691,9 @@ in error messages.
     ``file:line:column:end_line:end_column``. This option implies
     ``--show-column-numbers``.
 
-.. option:: --show-error-codes
+.. option:: --hide-error-codes
 
-    This flag will add an error code ``[<code>]`` to error messages. The error
+    This flag will hide the error code ``[<code>]`` from error messages. By default, the error
     code is shown after each error message::
 
         prog.py:1: error: "str" has no attribute "trim"  [attr-defined]

docs/source/config_file.rst

@@ -717,12 +717,12 @@ These options may only be set in the global section (``[mypy]``).
 
     Shows column numbers in error messages.
 
-.. confval:: show_error_codes
+.. confval:: hide_error_codes
 
     :type: boolean
     :default: False
 
-    Shows error codes in error messages. See :ref:`error-codes` for more information.
+    Hides error codes in error messages. See :ref:`error-codes` for more information.
 
 .. confval:: pretty
 

docs/source/error_codes.rst

@@ -23,12 +23,12 @@ Error codes may change in future mypy releases.
 Displaying error codes
 ----------------------
 
-Error codes are not displayed by default.  Use :option:`--show-error-codes <mypy --show-error-codes>`
-or config ``show_error_codes = True`` to display error codes. Error codes are shown inside square brackets:
+Error codes are displayed by default.  Use :option:`--hide-error-codes <mypy --hide-error-codes>`
+or config ``hide_error_codes = True`` to hide error codes. Error codes are shown inside square brackets:
 
 .. code-block:: text
 
-   $ mypy --show-error-codes prog.py
+   $ mypy prog.py
    prog.py:1: error: "str" has no attribute "trim"  [attr-defined]
 
 It's also possible to require error codes for ``type: ignore`` comments.

docs/source/type_inference_and_annotations.rst

@@ -229,8 +229,7 @@ short explanation of the bug. To do that, use this format:
     app.run(8000)  # type: ignore  # `run()` in v2.0 accepts an `int`, as a port
 
 
-Mypy displays an error code for each error if you use
-:option:`--show-error-codes <mypy --show-error-codes>`:
+By default, mypy displays an error code for each error:
 
 .. code-block:: text
 

mypy/build.py

@@ -237,7 +237,7 @@ def _build(
     errors = Errors(
         options.show_error_context,
         options.show_column_numbers,
-        options.show_error_codes,
+        options.hide_error_codes,
         options.pretty,
         options.show_error_end,
         lambda path: read_py_file(path, cached_read),

mypy/config_parser.py

@@ -431,6 +431,9 @@ def parse_section(
                 elif key.startswith("disallow") and hasattr(template, key[3:]):
                     options_key = key[3:]
                     invert = True
+                elif key.startswith("show_") and hasattr(template, "hide_" + key[5:]):
+                    options_key = "hide_" + key[5:]
+                    invert = True
                 elif key == "strict":
                     pass  # Special handling below
                 else:

mypy/dmypy_server.py

@@ -197,7 +197,7 @@ def __init__(self, options: Options, status_file: str, timeout: int | None = Non
 
         # Since the object is created in the parent process we can check
         # the output terminal options here.
-        self.formatter = FancyFormatter(sys.stdout, sys.stderr, options.show_error_codes)
+        self.formatter = FancyFormatter(sys.stdout, sys.stderr, options.hide_error_codes)
 
     def _response_metadata(self) -> dict[str, str]:
         py_version = f"{self.options.python_version[0]}_{self.options.python_version[1]}"

mypy/errors.py

@@ -257,7 +257,7 @@ def __init__(
         self,
         show_error_context: bool = False,
         show_column_numbers: bool = False,
-        show_error_codes: bool = False,
+        hide_error_codes: bool = False,
         pretty: bool = False,
         show_error_end: bool = False,
         read_source: Callable[[str], list[str] | None] | None = None,
@@ -267,7 +267,7 @@ def __init__(
     ) -> None:
         self.show_error_context = show_error_context
         self.show_column_numbers = show_column_numbers
-        self.show_error_codes = show_error_codes
+        self.hide_error_codes = hide_error_codes
         self.show_absolute_path = show_absolute_path
         self.pretty = pretty
         self.show_error_end = show_error_end
@@ -782,7 +782,7 @@ def format_messages(
                 s = f"{srcloc}: {severity}: {message}"
             else:
                 s = message
-            if self.show_error_codes and code and severity != "note":
+            if not self.hide_error_codes and code and severity != "note":
                 # If note has an error code, it is related to a previous error. Avoid
                 # displaying duplicate error codes.
                 s = f"{s}  [{code.code}]"

mypy/fastparse.py

@@ -258,11 +258,11 @@ def parse(
     on failure. Otherwise, use the errors object to report parse errors.
     """
     raise_on_error = False
-    if errors is None:
-        errors = Errors()
-        raise_on_error = True
     if options is None:
         options = Options()
+    if errors is None:
+        errors = Errors(hide_error_codes=options.hide_error_codes)
+        raise_on_error = True
     errors.set_file(fnam, module, options=options)
     is_stub_file = fnam.endswith(".pyi")
     if is_stub_file:

mypy/main.py

@@ -67,7 +67,7 @@ def main(
     if clean_exit:
         options.fast_exit = False
 
-    formatter = util.FancyFormatter(stdout, stderr, options.show_error_codes)
+    formatter = util.FancyFormatter(stdout, stderr, options.hide_error_codes)
 
     if options.install_types and (stdout is not sys.stdout or stderr is not sys.stderr):
         # Since --install-types performs user input, we want regular stdout and stderr.
@@ -151,7 +151,7 @@ def run_build(
     stdout: TextIO,
     stderr: TextIO,
 ) -> tuple[build.BuildResult | None, list[str], bool]:
-    formatter = util.FancyFormatter(stdout, stderr, options.show_error_codes)
+    formatter = util.FancyFormatter(stdout, stderr, options.hide_error_codes)
 
     messages = []
 
@@ -871,9 +871,9 @@ def add_invertible_flag(
         group=error_group,
     )
     add_invertible_flag(
-        "--show-error-codes",
+        "--hide-error-codes",
         default=False,
-        help="Show error codes in error messages",
+        help="Hide error codes in error messages",
         group=error_group,
     )
     add_invertible_flag(

mypy/options.py

@@ -276,7 +276,7 @@ def __init__(self) -> None:
         self.shadow_file: list[list[str]] | None = None
         self.show_column_numbers: bool = False
         self.show_error_end: bool = False
-        self.show_error_codes = False
+        self.hide_error_codes = False
         # Use soft word wrap and show trimmed source snippets with error location markers.
         self.pretty = False
         self.dump_graph = False

mypy/test/helpers.py

@@ -369,12 +369,15 @@ def parse_options(
         if targets:
             # TODO: support specifying targets via the flags pragma
             raise RuntimeError("Specifying targets via the flags pragma is not supported.")
+        if "--show-error-codes" not in flag_list:
+            options.hide_error_codes = True
     else:
         flag_list = []
         options = Options()
         # TODO: Enable strict optional in test cases by default (requires *many* test case changes)
         options.strict_optional = False
         options.error_summary = False
+        options.hide_error_codes = True
 
     # Allow custom python version to override testfile_pyversion.
     if all(flag.split("=")[0] not in ["--python-version", "-2", "--py2"] for flag in flag_list):

mypy/test/testcheck.py

@@ -119,7 +119,7 @@ def run_case_once(
         if "columns" in testcase.file:
             options.show_column_numbers = True
         if "errorcodes" in testcase.file:
-            options.show_error_codes = True
+            options.hide_error_codes = False
 
         if incremental_step and options.incremental:
             # Don't overwrite # flags: --no-incremental in incremental test cases

mypy/test/testcmdline.py

@@ -57,6 +57,8 @@ def test_python_cmdline(testcase: DataDrivenTestCase, step: int) -> None:
     args.append("--show-traceback")
     if "--error-summary" not in args:
         args.append("--no-error-summary")
+    if "--show-error-codes" not in args:
+        args.append("--hide-error-codes")
     # Type check the program.
     fixed = [python3_path, "-m", "mypy"]
     env = os.environ.copy()

mypy/test/testdaemon.py

@@ -81,6 +81,8 @@ def parse_script(input: list[str]) -> list[list[str]]:
 
 
 def run_cmd(input: str) -> tuple[int, str]:
+    if input[1:].startswith("mypy run --") and "--show-error-codes" not in input:
+        input += " --hide-error-codes"
     if input.startswith("dmypy "):
         input = sys.executable + " -m mypy." + input
     if input.startswith("mypy "):

mypy/test/testerrorstream.py

@@ -25,6 +25,7 @@ def test_error_stream(testcase: DataDrivenTestCase) -> None:
     """
     options = Options()
     options.show_traceback = True
+    options.hide_error_codes = True
 
     logged_messages: list[str] = []
 

mypy/test/testparse.py

@@ -32,6 +32,7 @@ def test_parser(testcase: DataDrivenTestCase) -> None:
     The argument contains the description of the test case.
     """
     options = Options()
+    options.hide_error_codes = True
 
     if testcase.file.endswith("python310.test"):
         options.python_version = (3, 10)

mypy/test/testpep561.py

@@ -107,7 +107,7 @@ def test_pep561(testcase: DataDrivenTestCase) -> None:
                     f.write(f"{s}\n")
             cmd_line.append(program)
 
-        cmd_line.extend(["--no-error-summary"])
+        cmd_line.extend(["--no-error-summary", "--hide-error-codes"])
         if python_executable != sys.executable:
             cmd_line.append(f"--python-executable={python_executable}")
 

mypy/test/testpythoneval.py

@@ -52,6 +52,7 @@ def test_python_evaluation(testcase: DataDrivenTestCase, cache_dir: str) -> None
         "--no-strict-optional",
         "--no-silence-site-packages",
         "--no-error-summary",
+        "--hide-error-codes",
     ]
     interpreter = python3_path
     mypy_cmdline.append(f"--python-version={'.'.join(map(str, PYTHON3_VERSION))}")

mypy/test/teststubtest.py

@@ -1559,13 +1559,13 @@ def test_mypy_build(self) -> None:
         output = run_stubtest(stub="+", runtime="", options=[])
         assert remove_color_code(output) == (
             "error: not checking stubs due to failed mypy compile:\n{}.pyi:1: "
-            "error: invalid syntax\n".format(TEST_MODULE_NAME)
+            "error: invalid syntax  [syntax]\n".format(TEST_MODULE_NAME)
         )
 
         output = run_stubtest(stub="def f(): ...\ndef f(): ...", runtime="", options=[])
         assert remove_color_code(output) == (
             "error: not checking stubs due to mypy build errors:\n{}.pyi:2: "
-            'error: Name "f" already defined on line 1\n'.format(TEST_MODULE_NAME)
+            'error: Name "f" already defined on line 1  [no-redef]\n'.format(TEST_MODULE_NAME)
         )
 
     def test_missing_stubs(self) -> None:

mypy/util.py

@@ -522,8 +522,8 @@ class FancyFormatter:
     This currently only works on Linux and Mac.
     """
 
-    def __init__(self, f_out: IO[str], f_err: IO[str], show_error_codes: bool) -> None:
-        self.show_error_codes = show_error_codes
+    def __init__(self, f_out: IO[str], f_err: IO[str], hide_error_codes: bool) -> None:
+        self.hide_error_codes = hide_error_codes
         # Check if we are in a human-facing terminal on a supported platform.
         if sys.platform not in ("linux", "darwin", "win32", "emscripten"):
             self.dummy_term = True
@@ -690,7 +690,7 @@ def colorize(self, error: str) -> str:
         """Colorize an output line by highlighting the status and error code."""
         if ": error:" in error:
             loc, msg = error.split("error:", maxsplit=1)
-            if not self.show_error_codes:
+            if self.hide_error_codes:
                 return (
                     loc + self.style("error:", "red", bold=True) + self.highlight_quote_groups(msg)
                 )

mypy_self_check.ini

@@ -5,7 +5,6 @@ warn_no_return = True
 strict_optional = True
 disallow_any_unimported = True
 show_traceback = True
-show_error_codes = True
 pretty = True
 always_false = MYPYC
 plugins = misc/proper_plugin.py

mypyc/errors.py

@@ -7,7 +7,7 @@ class Errors:
     def __init__(self) -> None:
         self.num_errors = 0
         self.num_warnings = 0
-        self._errors = mypy.errors.Errors()
+        self._errors = mypy.errors.Errors(hide_error_codes=True)
 
     def error(self, msg: str, path: str, line: int) -> None:
         self._errors.report(line, None, msg, severity="error", file=path)

mypyc/test/testutil.py

@@ -105,6 +105,7 @@ def build_ir_for_single_file2(
     compiler_options = compiler_options or CompilerOptions(capi_version=(3, 5))
     options = Options()
     options.show_traceback = True
+    options.hide_error_codes = True
     options.use_builtins_fixtures = True
     options.strict_optional = True
     options.python_version = (3, 6)

test-data/unit/check-errorcodes.test

@@ -922,3 +922,12 @@ def f(d: D, s: str) -> None:
 [case testRecommendErrorCode]
 # type: ignore[whatever]  # E: type ignore with error code is not supported for modules; use `# mypy: disable-error-code=...`  [syntax]
 1 + "asdf"
+
+[case testShowErrorCodesInConfig]
+# flags: --config-file tmp/mypy.ini
+# Test 'show_error_codes = True' in config doesn't raise an exception
+var: int = ""  # E: Incompatible types in assignment (expression has type "str", variable has type "int")  [assignment]
+
+[file mypy.ini]
+\[mypy]
+show_error_codes = True

test-data/unit/check-flags.test

@@ -2023,12 +2023,12 @@ x = 'should be fine'
 x.trim()
 
 [case testDisableDifferentErrorCode]
-# flags: --disable-error-code name-defined --show-error-code
+# flags: --disable-error-code name-defined --show-error-codes
 x = 'should not be fine'
 x.trim()  # E: "str" has no attribute "trim"  [attr-defined]
 
 [case testDisableMultipleErrorCode]
-# flags: --disable-error-code attr-defined --disable-error-code return-value --show-error-code
+# flags: --disable-error-code attr-defined --disable-error-code return-value --show-error-codes
 x = 'should be fine'
 x.trim()
 
@@ -2038,12 +2038,12 @@ def bad_return_type() -> str:
 bad_return_type('no args taken!')  # E: Too many arguments for "bad_return_type"  [call-arg]
 
 [case testEnableErrorCode]
-# flags: --disable-error-code attr-defined --enable-error-code attr-defined --show-error-code
+# flags: --disable-error-code attr-defined --enable-error-code attr-defined --show-error-codes
 x = 'should be fine'
 x.trim()  # E: "str" has no attribute "trim"  [attr-defined]
 
 [case testEnableDifferentErrorCode]
-# flags: --disable-error-code attr-defined --enable-error-code name-defined --show-error-code
+# flags: --disable-error-code attr-defined --enable-error-code name-defined --show-error-codes
 x = 'should not be fine'
 x.trim()
 y.trim()  # E: Name "y" is not defined  [name-defined]
@@ -2054,7 +2054,7 @@ y.trim()  # E: Name "y" is not defined  [name-defined]
     --disable-error-code return-value \
     --disable-error-code call-arg \
     --enable-error-code attr-defined \
-    --enable-error-code return-value --show-error-code
+    --enable-error-code return-value --show-error-codes
 x = 'should be fine'
 x.trim()  # E: "str" has no attribute "trim"  [attr-defined]
 
@@ -2109,3 +2109,11 @@ enable_error_code = ignore-without-code, truthy-bool
 
 \[mypy-tests.*]
 disable_error_code = ignore-without-code
+
+[case testShowErrorCodes]
+# flags: --show-error-codes
+x: int = ""  # E: Incompatible types in assignment (expression has type "str", variable has type "int")  [assignment]
+
+[case testHideErrorCodes]
+# flags: --hide-error-codes
+x: int = ""  # E: Incompatible types in assignment (expression has type "str", variable has type "int")

test-data/unit/daemon.test

@@ -185,7 +185,7 @@ Daemon started
 $ dmypy check foo.py bar.py
 $ dmypy recheck
 $ dmypy recheck --update foo.py --remove bar.py sir_not_appearing_in_this_film.py
-foo.py:1: error: Import of "bar" ignored
+foo.py:1: error: Import of "bar" ignored  [misc]
 foo.py:1: note: (Using --follow-imports=error, module not passed on command line)
 == Return code: 1
 $ dmypy recheck --update bar.py
@@ -277,7 +277,7 @@ $ dmypy suggest foo.foo
 (str) -> int
 $ {python} -c "import shutil; shutil.copy('foo2.py', 'foo.py')"
 $ dmypy check foo.py bar.py
-bar.py:3: error: Incompatible types in assignment (expression has type "int", variable has type "str")
+bar.py:3: error: Incompatible types in assignment (expression has type "int", variable has type "str")  [assignment]
 == Return code: 1
 [file foo.py]
 def foo(arg):
@@ -304,7 +304,7 @@ $ dmypy inspect foo:1:2:3:4
 Command "inspect" is only valid after a "check" command (that produces no parse errors)
 == Return code: 2
 $ dmypy check foo.py --export-types
-foo.py:3: error: Incompatible types in assignment (expression has type "str", variable has type "int")
+foo.py:3: error: Incompatible types in assignment (expression has type "str", variable has type "int")  [assignment]
 == Return code: 1
 $ dmypy inspect foo:1
 Format should be file:line:column[:end_line:end_column]