Add test for ambiguous short names in error messages

Author: Muks14x

mypy/messages.py

@@ -15,7 +15,6 @@
 from textwrap import dedent
 import builtins
 
-import typing
 from typing import cast, List, Dict, Any, Sequence, Iterable, Tuple, Set, Optional, Union
 from typing_extensions import Final
 
@@ -44,6 +43,21 @@
 from mypy.errorcodes import ErrorCode
 from mypy import message_registry, errorcodes as codes
 
+TYPES_FOR_UNIMPORTED_HINTS = {
+    'typing.Any',
+    'typing.Callable',
+    'typing.Dict',
+    'typing.Iterable',
+    'typing.Iterator',
+    'typing.List',
+    'typing.Optional',
+    'typing.Set',
+    'typing.Tuple',
+    'typing.TypeVar',
+    'typing.Union',
+    'typing.cast',
+}  # type: Final
+
 
 ARG_CONSTRUCTOR_NAMES = {
     ARG_POS: "Arg",
@@ -1720,14 +1734,14 @@ def find_type_overlaps(*types: Type) -> Set[str]:
     """
     d = {}  # type: Dict[str, Set[str]]
     builtin_types = set(dir(builtins))
-    typing_types = set(dir(typing))
     for type in types:
         for inst in collect_all_instances(type):
             d.setdefault(inst.type.name, set()).add(inst.type.fullname)
-            if inst.type.name in builtin_types:
-                d[inst.type.name].add('builtins.{}'.format(inst.type.name))
-            if inst.type.name in typing_types:
-                d[inst.type.name].add('typing.{}'.format(inst.type.name))
+    for shortname in d.keys():
+        if shortname in builtin_types:
+            d[shortname].add('builtins.{}'.format(shortname))
+        if 'typing.{}'.format(shortname) in TYPES_FOR_UNIMPORTED_HINTS:
+            d[shortname].add('typing.{}'.format(shortname))
 
     overlaps = set()  # type: Set[str]
     for fullnames in d.values():

mypy/semanal.py

@@ -81,7 +81,9 @@
 from mypy.typevars import fill_typevars
 from mypy.visitor import NodeVisitor
 from mypy.errors import Errors, report_internal_error
-from mypy.messages import best_matches, MessageBuilder, pretty_seq, SUGGESTED_TEST_FIXTURES
+from mypy.messages import (
+    best_matches, MessageBuilder, pretty_seq, SUGGESTED_TEST_FIXTURES, TYPES_FOR_UNIMPORTED_HINTS
+)
 from mypy.errorcodes import ErrorCode
 from mypy import message_registry, errorcodes as codes
 from mypy.types import (
@@ -120,21 +122,6 @@
 
 T = TypeVar('T')
 
-TYPES_FOR_UNIMPORTED_HINTS = {
-    'typing.Any',
-    'typing.Callable',
-    'typing.Dict',
-    'typing.Iterable',
-    'typing.Iterator',
-    'typing.List',
-    'typing.Optional',
-    'typing.Set',
-    'typing.Tuple',
-    'typing.TypeVar',
-    'typing.Union',
-    'typing.cast',
-}  # type: Final
-
 
 # Special cased built-in classes that are needed for basic functionality and need to be
 # available very early on.

test-data/unit/check-basic.test

@@ -75,6 +75,18 @@ if int():
     x = 1
 
 
+[case testIncompatibleAssignmentAmbiguousShortnames]
+
+class Any: pass
+class float: pass
+
+x = Any()
+x = 1  # E: Incompatible types in assignment (expression has type "int", variable has type "__main__.Any")
+
+y = float()
+y = 1.0  # E: Incompatible types in assignment (expression has type "builtins.float", variable has type "__main__.float")
+
+
 -- Simple functions and calling
 -- ----------------------------
 

test-data/unit/fine-grained.test

@@ -5137,8 +5137,8 @@ def g(x: T) -> T:
     pass
 [out]
 ==
-a.py:2: error: Incompatible types in assignment (expression has type "c.T", variable has type "int")
-a.py:2: error: Argument "x" has incompatible type "int"; expected "c.T"
+a.py:2: error: Incompatible types in assignment (expression has type "T", variable has type "int")
+a.py:2: error: Argument "x" has incompatible type "int"; expected "T"
 
 [case testGenericFineCallableToGenericClass]
 import a
@@ -7055,7 +7055,7 @@ class T: pass
 a.py:2: error: No overload variant of "f" matches argument type "int"
 a.py:2: note: Possible overload variants:
 a.py:2: note:     def f(x: C) -> None
-a.py:2: note:     def f(x: c.T) -> c.T
+a.py:2: note:     def f(x: T) -> T
 
 [case testOverloadsToNonOverloaded]
 import a

test-data/unit/pythoneval.test

@@ -904,7 +904,7 @@ reveal_type(o6)
 
 [out]
 _testCollectionsAliases.py:5: note: Revealed type is 'collections.Counter[builtins.int]'
-_testCollectionsAliases.py:6: error: Invalid index type "str" for "collections.Counter[int]"; expected type "int"
+_testCollectionsAliases.py:6: error: Invalid index type "str" for "Counter[int]"; expected type "int"
 _testCollectionsAliases.py:9: note: Revealed type is 'collections.ChainMap[builtins.int, builtins.str]'
 _testCollectionsAliases.py:12: note: Revealed type is 'collections.deque[builtins.int]'
 _testCollectionsAliases.py:15: note: Revealed type is 'collections.Counter[builtins.int*]'