diff --git a/docs/source/command_line.rst b/docs/source/command_line.rst
index ea3c91396f31c..69d1a7b80fde6 100644
--- a/docs/source/command_line.rst
+++ b/docs/source/command_line.rst
@@ -687,6 +687,14 @@ in error messages.
Show absolute paths to files.
+.. option:: --soft-error-limit N
+
+ This flag will adjust the limit after which mypy will (sometimes)
+ disable reporting most additional errors. The limit only applies
+ if it seems likely that most of the remaining errors will not be
+ useful or they may be overly noisy. If ``N`` is negative, there is
+ no limit. The default limit is 200.
+
.. _incremental:
diff --git a/mypy/build.py b/mypy/build.py
index 6b5f83aa6e097..499f027d8faea 100644
--- a/mypy/build.py
+++ b/mypy/build.py
@@ -224,7 +224,8 @@ def _build(sources: List[BuildSource],
lambda path: read_py_file(path, cached_read, options.python_version),
options.show_absolute_path,
options.enabled_error_codes,
- options.disabled_error_codes)
+ options.disabled_error_codes,
+ options.many_errors_threshold)
plugin, snapshot = load_plugins(options, errors, stdout, extra_plugins)
# Add catch-all .gitignore to cache dir if we created it
diff --git a/mypy/defaults.py b/mypy/defaults.py
index 7e19bfe4a56fc..49543cfcecaa6 100644
--- a/mypy/defaults.py
+++ b/mypy/defaults.py
@@ -30,3 +30,7 @@
'html',
'txt',
'lineprecision'] # type: Final
+
+# Threshold after which we sometimes filter out most errors to avoid very
+# verbose output
+MANY_ERRORS_THRESHOLD = 200 # type: Final
diff --git a/mypy/errors.py b/mypy/errors.py
index b3f99916b244d..948daaa72e3ea 100644
--- a/mypy/errors.py
+++ b/mypy/errors.py
@@ -10,7 +10,7 @@
from mypy.scope import Scope
from mypy.options import Options
from mypy.version import __version__ as mypy_version
-from mypy.errorcodes import ErrorCode
+from mypy.errorcodes import ErrorCode, IMPORT
from mypy import errorcodes as codes
from mypy.util import DEFAULT_SOURCE_OFFSET, is_typeshed_file
@@ -65,6 +65,10 @@ class ErrorInfo:
# Fine-grained incremental target where this was reported
target = None # type: Optional[str]
+ # If True, don't show this message in output, but still record the error (needed
+ # by mypy daemon)
+ hidden = False
+
def __init__(self,
import_ctx: List[Tuple[str, int]],
file: str,
@@ -158,6 +162,10 @@ class Errors:
target_module = None # type: Optional[str]
scope = None # type: Optional[Scope]
+ # Have we seen an import-related error so far? If yes, we filter out other messages
+ # in some cases to avoid reporting huge numbers of errors.
+ seen_import_error = False
+
def __init__(self,
show_error_context: bool = False,
show_column_numbers: bool = False,
@@ -166,7 +174,8 @@ def __init__(self,
read_source: Optional[Callable[[str], Optional[List[str]]]] = None,
show_absolute_path: bool = False,
enabled_error_codes: Optional[Set[ErrorCode]] = None,
- disabled_error_codes: Optional[Set[ErrorCode]] = None) -> None:
+ disabled_error_codes: Optional[Set[ErrorCode]] = None,
+ many_errors_threshold: int = -1) -> None:
self.show_error_context = show_error_context
self.show_column_numbers = show_column_numbers
self.show_error_codes = show_error_codes
@@ -176,6 +185,7 @@ def __init__(self,
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.initialize()
def initialize(self) -> None:
@@ -189,6 +199,7 @@ def initialize(self) -> None:
self.only_once_messages = set()
self.scope = None
self.target_module = None
+ self.seen_import_error = False
def reset(self) -> None:
self.initialize()
@@ -201,12 +212,14 @@ def copy(self) -> 'Errors':
self.read_source,
self.show_absolute_path,
self.enabled_error_codes,
- self.disabled_error_codes)
+ self.disabled_error_codes,
+ self.many_errors_threshold)
new.file = self.file
new.import_ctx = self.import_ctx[:]
new.function_or_member = self.function_or_member[:]
new.target_module = self.target_module
new.scope = self.scope
+ new.seen_import_error = self.seen_import_error
return new
def total_errors(self) -> int:
@@ -330,6 +343,8 @@ def _add_error_info(self, file: str, info: ErrorInfo) -> None:
if file not in self.error_info_map:
self.error_info_map[file] = []
self.error_info_map[file].append(info)
+ if info.code is IMPORT:
+ self.seen_import_error = True
def add_error_info(self, info: ErrorInfo) -> None:
file, line, end_line = info.origin
@@ -354,8 +369,52 @@ def add_error_info(self, info: ErrorInfo) -> None:
if info.message in self.only_once_messages:
return
self.only_once_messages.add(info.message)
+ if self.seen_import_error and info.code is not IMPORT and self.has_many_errors():
+ # Missing stubs can easily cause thousands of errors about
+ # Any types, especially when upgrading to mypy 0.900,
+ # which no longer bundles third-party library stubs. Avoid
+ # showing too many errors to make it easier to see
+ # import-related errors.
+ info.hidden = True
+ self.report_hidden_errors(info)
self._add_error_info(file, info)
+ def has_many_errors(self) -> bool:
+ if self.many_errors_threshold < 0:
+ return False
+ if len(self.error_info_map) >= self.many_errors_threshold:
+ return True
+ if sum(len(errors)
+ for errors in self.error_info_map.values()) >= self.many_errors_threshold:
+ return True
+ return False
+
+ def report_hidden_errors(self, info: ErrorInfo) -> None:
+ message = (
+ '(Skipping most remaining errors due to unresolved imports or missing stubs; ' +
+ 'fix these first)'
+ )
+ if message in self.only_once_messages:
+ return
+ self.only_once_messages.add(message)
+ new_info = ErrorInfo(
+ import_ctx=info.import_ctx,
+ file=info.file,
+ module=info.module,
+ typ=None,
+ function_or_member=None,
+ line=info.line,
+ column=info.line,
+ severity='note',
+ message=message,
+ code=None,
+ blocker=False,
+ only_once=True,
+ origin=info.origin,
+ target=info.target,
+ )
+ self._add_error_info(info.origin[0], new_info)
+
def is_ignored_error(self, line: int, info: ErrorInfo, ignores: Dict[int, List[str]]) -> bool:
if info.blocker:
# Blocking errors can never be ignored
@@ -453,6 +512,7 @@ def format_messages(self, error_info: List[ErrorInfo],
severity 'error').
"""
a = [] # type: List[str]
+ error_info = [info for info in error_info if not info.hidden]
errors = self.render_messages(self.sort_messages(error_info))
errors = self.remove_duplicates(errors)
for file, line, column, severity, message, code in errors:
diff --git a/mypy/main.py b/mypy/main.py
index f3625553f6818..201710f6cebc6 100644
--- a/mypy/main.py
+++ b/mypy/main.py
@@ -663,6 +663,8 @@ def add_invertible_flag(flag: str,
add_invertible_flag('--show-absolute-path', default=False,
help="Show absolute paths to files",
group=error_group)
+ error_group.add_argument('--soft-error-limit', default=defaults.MANY_ERRORS_THRESHOLD,
+ type=int, dest="many_errors_threshold", help=argparse.SUPPRESS)
incremental_group = parser.add_argument_group(
title='Incremental mode',
diff --git a/mypy/options.py b/mypy/options.py
index 9e41ad7d310d9..a19a7fedc0fc8 100644
--- a/mypy/options.py
+++ b/mypy/options.py
@@ -295,6 +295,10 @@ def __init__(self) -> None:
self.show_absolute_path = False # type: bool
# Install missing stub packages if True
self.install_types = False
+ # When we encounter errors that may cause many additional errors,
+ # skip most errors after this many messages have been reported.
+ # -1 means unlimited.
+ self.many_errors_threshold = defaults.MANY_ERRORS_THRESHOLD
# To avoid breaking plugin compatibility, keep providing new_semantic_analyzer
@property
diff --git a/test-data/unit/check-modules.test b/test-data/unit/check-modules.test
index ddabfe252253d..d06dfb413275b 100644
--- a/test-data/unit/check-modules.test
+++ b/test-data/unit/check-modules.test
@@ -2982,3 +2982,85 @@ T = TypeVar("T")
class F(M):
x: C
class C: ...
+
+[case testLimitLegacyStubErrorVolume]
+# flags: --disallow-any-expr --soft-error-limit=5
+import certifi # E: Cannot find implementation or library stub for module named "certifi" \
+ # N: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # N: (Skipping most remaining errors due to unresolved imports or missing stubs; fix these first)
+certifi.x
+certifi.x
+certifi.x
+certifi.x
+
+[case testDoNotLimitErrorVolumeIfNotImportErrors]
+# flags: --disallow-any-expr --soft-error-limit=5
+def f(): pass
+certifi = f() # E: Expression has type "Any"
+1() # E: "int" not callable
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+1() # E: "int" not callable
+
+
+[case testDoNotLimitImportErrorVolume]
+# flags: --disallow-any-expr --soft-error-limit=3
+import xyz1 # E: Cannot find implementation or library stub for module named "xyz1" \
+ # N: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
+import xyz2 # E: Cannot find implementation or library stub for module named "xyz2"
+import xyz3 # E: Cannot find implementation or library stub for module named "xyz3"
+import xyz4 # E: Cannot find implementation or library stub for module named "xyz4"
+
+[case testUnlimitedStubErrorVolume]
+# flags: --disallow-any-expr --soft-error-limit=-1
+import certifi # E: Cannot find implementation or library stub for module named "certifi" \
+ # N: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"
+certifi.x # E: Expression has type "Any"