Don't erase type object args in diagnostics (#18352)

Fixes #16875

Author: hauntsaninja

mypy/messages.py

@@ -2700,7 +2700,7 @@ def format_literal_value(typ: LiteralType) -> str:
         if func.is_type_obj():
             # The type of a type object type can be derived from the
             # return type (this always works).
-            return format(TypeType.make_normalized(erase_type(func.items[0].ret_type)))
+            return format(TypeType.make_normalized(func.items[0].ret_type))
         elif isinstance(func, CallableType):
             if func.type_guard is not None:
                 return_type = f"TypeGuard[{format(func.type_guard)}]"

test-data/unit/check-generics.test

@@ -1773,8 +1773,7 @@ T = TypeVar('T')
 class C(Generic[T]):
     def __init__(self) -> None: pass
 x = C # type: Callable[[], C[int]]
-y = C # type: Callable[[], int] # E: Incompatible types in assignment (expression has type "Type[C[Any]]", variable has type "Callable[[], int]")
-
+y = C # type: Callable[[], int] # E: Incompatible types in assignment (expression has type "Type[C[T]]", variable has type "Callable[[], int]")
 
 -- Special cases
 -- -------------

test-data/unit/check-inference.test

@@ -2488,7 +2488,7 @@ T = TypeVar('T')
 class C(Sequence[T], Generic[T]): pass
 C[0] = 0
 [out]
-main:4: error: Unsupported target for indexed assignment ("Type[C[Any]]")
+main:4: error: Unsupported target for indexed assignment ("Type[C[T]]")
 main:4: error: Invalid type: try using Literal[0] instead?
 
 [case testNoCrashOnPartialMember]

test-data/unit/check-newsemanal.test

@@ -2743,13 +2743,11 @@ T = TypeVar('T')
 
 class C(Generic[T]):
     pass
-# TODO: Error message is confusing
+
 C = C[int]  # E: Cannot assign to a type \
-            # E: Incompatible types in assignment (expression has type "Type[C[Any]]", variable has type "Type[C[Any]]")
+            # E: Incompatible types in assignment (expression has type "Type[C[int]]", variable has type "Type[C[T]]")
 x: C
 reveal_type(x) # N: Revealed type is "__main__.C[Any]"
-[out]
-[out2]
 
 [case testNewAnalyzerClassVariableOrdering]
 def foo(x: str) -> None: pass

test-data/unit/fine-grained-inspect.test

@@ -23,7 +23,7 @@ NameExpr -> "C[T]"
 MemberExpr -> "T"
 NameExpr -> "C[T]"
 MemberExpr -> "T"
-12:5:12:5 -> "Type[foo.C[Any]]"
+12:5:12:5 -> "Type[foo.C[builtins.int]]"
 12:5:12:9 -> "foo.C[builtins.int]"
 12:1:12:10 -> "builtins.int"
 CallExpr:12:5:12:9 -> "C[int]"

test-data/unit/pythoneval.test

@@ -823,7 +823,7 @@ class MyDDict(t.DefaultDict[int,T], t.Generic[T]):
 MyDDict(dict)['0']
 MyDDict(dict)[0]
 [out]
-_program.py:7: error: Argument 1 to "defaultdict" has incompatible type "Type[List[Any]]"; expected "Optional[Callable[[], str]]"
+_program.py:7: error: Argument 1 to "defaultdict" has incompatible type "Type[List[_T]]"; expected "Optional[Callable[[], str]]"
 _program.py:10: error: Invalid index type "str" for "defaultdict[int, str]"; expected type "int"
 _program.py:10: error: Incompatible types in assignment (expression has type "int", target has type "str")
 _program.py:20: error: Argument 1 to "tst" has incompatible type "defaultdict[str, List[Never]]"; expected "defaultdict[int, List[Never]]"