Add --suppress-error-context flag to suppress notes about class/function (#1922)

Fixes #1821. (well enough for now)

Author: gvanrossum

mypy/build.py

@@ -330,7 +330,7 @@ def __init__(self, data_dir: str,
                  options: Options) -> None:
         self.start_time = time.time()
         self.data_dir = data_dir
-        self.errors = Errors()
+        self.errors = Errors(options.suppress_error_context)
         self.errors.set_ignore_prefix(ignore_prefix)
         self.lib_path = tuple(lib_path)
         self.source_set = source_set

mypy/errors.py

@@ -89,17 +89,21 @@ class Errors:
     # Collection of reported only_once messages.
     only_once_messages = None  # type: Set[str]
 
-    def __init__(self) -> None:
+    # Set to True to suppress "In function "foo":" messages.
+    suppress_error_context = False  # type: bool
+
+    def __init__(self, suppress_error_context: bool = False) -> None:
         self.error_info = []
         self.import_ctx = []
         self.type_name = [None]
         self.function_or_member = [None]
         self.ignored_lines = OrderedDict()
         self.used_ignored_lines = defaultdict(set)
         self.only_once_messages = set()
+        self.suppress_error_context = suppress_error_context
 
     def copy(self) -> 'Errors':
-        new = Errors()
+        new = Errors(self.suppress_error_context)
         new.file = self.file
         new.import_ctx = self.import_ctx[:]
         new.type_name = self.type_name[:]
@@ -287,7 +291,9 @@ def render_messages(self, errors: List[ErrorInfo]) -> List[Tuple[str, int,
             file = self.simplify_path(e.file)
 
             # Report context within a source file.
-            if (e.function_or_member != prev_function_or_member or
+            if self.suppress_error_context:
+                pass
+            elif (e.function_or_member != prev_function_or_member or
                     e.type != prev_type):
                 if e.function_or_member is None:
                     if e.type is None:

mypy/main.py

@@ -162,6 +162,9 @@ def parse_version(v: str) -> Tuple[int, int]:
                         help="warn about casting an expression to its inferred type")
     parser.add_argument('--warn-unused-ignores', action='store_true',
                         help="warn about unneeded '# type: ignore' comments")
+    parser.add_argument('--suppress-error-context', action='store_true',
+                        dest='suppress_error_context',
+                        help="Suppress context notes before errors")
     parser.add_argument('--fast-parser', action='store_true',
                         help="enable experimental fast parser")
     parser.add_argument('-i', '--incremental', action='store_true',

mypy/options.py

@@ -56,6 +56,7 @@ def __init__(self) -> None:
         self.fast_parser = False
         self.incremental = False
         self.cache_dir = defaults.MYPY_CACHE
+        self.suppress_error_context = False  # Suppress "note: In function "foo":" messages.
 
     def __eq__(self, other: object) -> bool:
         return self.__class__ == other.__class__ and self.__dict__ == other.__dict__