Map class type parameters to superclass when checking class method use

Fixes python#1337.

Author: rwbarton

mypy/checkmember.py

@@ -300,6 +300,11 @@ def analyze_class_attribute_access(itype: Instance,
 
     t = node.type
     if t:
+        if isinstance(node.node, Decorator):
+            info = node.node.var.info
+        elif isinstance(node.node, (Var, FuncBase)):
+            info = node.node.info
+        t = map_type_from_supertype(t, itype.type, info)
         if isinstance(t, PartialType):
             return handle_partial_attribute_type(t, is_lvalue, msg, node.node)
         is_classmethod = is_decorated and cast(Decorator, node.node).func.is_class

test-data/unit/check-generics.test

@@ -188,6 +188,71 @@ main:9: error: Incompatible types in assignment (expression has type A[C, B], va
 main:10: error: Incompatible types in assignment (expression has type A[B, B], variable has type A[B, C])
 
 
+[case testClassMethodOfGenericClass]
+from typing import TypeVar, Generic
+T = TypeVar('T')
+U = TypeVar('U')
+class X(Generic[T,U]):
+    def __init__(self, t: T, u: U) -> None:
+        pass
+
+class A(Generic[T]):
+    @classmethod
+    def f(cls, x: T) -> T:
+        pass
+    @classmethod
+    def g(cls) -> T:
+        pass
+class B(A[X[int, T]], Generic[T]):
+    pass
+class C(B[str]):
+    pass
+
+A.f(3)() # E: "int" not callable
+B.f(3) # E: Argument 1 to "f" of "A" has incompatible type "int"; expected X[int, None]
+B.f(X(3, 4))() # E: X[int, int] not callable
+C.f(X(3, 4)) # E: Argument 2 to "X" has incompatible type "int"; expected "str"
+C.f(X(3, 'a'))() # E: X[int, str] not callable
+
+ga = A.g() # E: Need type annotation for variable
+gb = B.g() # E: Need type annotation for variable
+gc = C.g()
+gc() # E: X[int, str] not callable
+[builtins fixtures/classmethod.py]
+
+[case testStaticMethodOfGenericClass]
+from typing import TypeVar, Generic
+T = TypeVar('T')
+U = TypeVar('U')
+class X(Generic[T,U]):
+    def __init__(self, t: T, u: U) -> None:
+        pass
+
+class A(Generic[T]):
+    @staticmethod
+    def f(x: T) -> T:
+        pass
+    @staticmethod
+    def g() -> T:
+        pass
+class B(A[X[int, T]], Generic[T]):
+    pass
+class C(B[str]):
+    pass
+
+A.f(3)() # E: "int" not callable
+B.f(3) # E: Argument 1 to "f" of "A" has incompatible type "int"; expected X[int, None]
+B.f(X(3, 4))() # E: X[int, int] not callable
+C.f(X(3, 4)) # E: Argument 2 to "X" has incompatible type "int"; expected "str"
+C.f(X(3, 'a'))() # E: X[int, str] not callable
+
+ga = A.g() # E: Need type annotation for variable
+gb = B.g() # E: Need type annotation for variable
+gc = C.g()
+gc() # E: X[int, str] not callable
+[builtins fixtures/staticmethod.py]
+
+
 -- Simple generic type bodies
 -- --------------------------