Expand imports in classes

mypy/semanal.py

@@ -1869,6 +1869,15 @@ def visit_import_from(self, imp: ImportFrom) -> None:
                     continue
 
             if node and not node.module_hidden:
+                # expand into importing class, too... unless there's something already there.
+                # (deciding what expands is based on line order which cannot be checked here.)
+                if self.is_class_scope():
+                    assert self.type is not None
+                    defn = node.node
+                    if imported_id not in self.type.names.keys() and isinstance(defn, FuncDef):
+                        if not defn.is_decorated and not defn.is_overload:
+                            defn.info = self.type
+                            self.add_symbol(defn.name, defn, imp)
                 self.process_imported_symbol(
                     node, module_id, id, imported_id, fullname, module_public, context=imp
                 )

test-data/unit/check-classes.test

@@ -6968,3 +6968,68 @@ class B(A):  # E: Final class __main__.B has abstract attributes "foo"
 [case testUndefinedBaseclassInNestedClass]
 class C:
     class C1(XX): pass  # E: Name "XX" is not defined
+
+[case testExpandImportedMethodInClass]
+# https://github.com/python/mypy/issues/7045
+class Foo:
+    from a import meth
+
+reveal_type(Foo().meth)  # N: Revealed type is "def (x: builtins.int) -> builtins.int"
+[file a.py]
+def meth(self, x: int) -> int:
+    ...
+
+[case testExpandImportedFunctionInClass]
+class Foo:
+    from a import func
+
+reveal_type(Foo.func)  # N: Revealed type is "def () -> builtins.str"
+[file a.py]
+def func() -> str:
+    ...
+
+[case testExpandImportedMethodInNestedClass]
+class Foo:
+    class Bar:
+        from a import meth
+
+reveal_type(Foo.Bar().meth)  # N: Revealed type is "def (x: builtins.int) -> builtins.int"
+[file a.py]
+def meth(self, x: int) -> int:
+    ...
+
+[case testExpandUndefinedImports]
+class Foo:
+    from not_a_module import func
+
+reveal_type(Foo.func)
+reveal_type(Foo().func)
+[out]
+main:2: error: Cannot find implementation or library stub for module named "not_a_module"
+main:2: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
+main:4: note: Revealed type is "Any"
+main:5: note: Revealed type is "Any"
+
+[case testExpandImportedMethodWithFollowImports]
+# flags: --follow-imports=skip
+class Foo:
+    from a import meth
+
+reveal_type(Foo().meth)  # N: Revealed type is "Any"
+[file a.py]
+def meth(self, x: int) -> int:
+    ...
+
+[case testExpandWithNonSelfFirstArgument]
+class Foo:
+    from a import func
+
+reveal_type(Foo().func)
+reveal_type(Foo.func)
+[file a.py]
+def func(self: str, x: int) -> int:
+    ...
+[out]
+main:4: error: Invalid self argument "Foo" to attribute function "func" with type "Callable[[str, int], int]"
+main:4: note: Revealed type is "def (x: builtins.int) -> builtins.int"
+main:5: note: Revealed type is "def (self: builtins.str, x: builtins.int) -> builtins.int"