From c11f99c1a24b472271c3c7fc8c93212f0bf3e5ab Mon Sep 17 00:00:00 2001
From: Michael Krasnyk <michael.krasnyk@gmail.com>
Date: Sat, 7 May 2022 21:06:21 +0200
Subject: [PATCH] Fix reporting location in aliased types.

---
 mypy/types.py                      | 14 ++++++++++++++
 test-data/unit/check-generics.test | 24 ++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/mypy/types.py b/mypy/types.py
index b7e76c9f9f6b..df0999ed3ca6 100644
--- a/mypy/types.py
+++ b/mypy/types.py
@@ -2760,6 +2760,7 @@ def get_proper_types(
     TypeTranslator as TypeTranslator,
     TypeVisitor as TypeVisitor,
 )
+from mypy.typetraverser import TypeTraverserVisitor
 
 
 class TypeStrVisitor(SyntheticTypeVisitor[str]):
@@ -3122,6 +3123,18 @@ def visit_type_var(self, typ: TypeVarType) -> Type:
         return typ
 
 
+class LocationSetter(TypeTraverserVisitor):
+    # TODO: Should we update locations of other Type subclasses?
+    def __init__(self, line: int, column: int) -> None:
+        self.line = line
+        self.column = column
+
+    def visit_instance(self, typ: Instance) -> None:
+        typ.line = self.line
+        typ.column = self.column
+        super().visit_instance(typ)
+
+
 def replace_alias_tvars(
     tp: Type, vars: List[str], subs: List[Type], newline: int, newcolumn: int
 ) -> Type:
@@ -3130,6 +3143,7 @@ def replace_alias_tvars(
     """
     replacer = InstantiateAliasVisitor(vars, subs)
     new_tp = tp.accept(replacer)
+    new_tp.accept(LocationSetter(newline, newcolumn))
     new_tp.line = newline
     new_tp.column = newcolumn
     return new_tp
diff --git a/test-data/unit/check-generics.test b/test-data/unit/check-generics.test
index c52addbad182..b8d70d1dae96 100644
--- a/test-data/unit/check-generics.test
+++ b/test-data/unit/check-generics.test
@@ -648,6 +648,30 @@ reveal_type(f3()) # N: Revealed type is "Union[builtins.int, __main__.Node[built
 
 [builtins fixtures/list.pyi]
 
+[case testGenericTypeAliasesWithNestedArgs]
+# flags: --pretty --show-error-codes
+import other
+a: other.Array[float]
+reveal_type(a) # N: Revealed type is "other.array[Any, other.dtype[builtins.float]]"
+
+[out]
+main:3: error: Type argument "float" of "dtype" must be a subtype of "generic"  [type-var]
+    a: other.Array[float]
+       ^
+[file other.py]
+from typing import Any, Generic, TypeVar
+
+DT = TypeVar("DT", covariant=True, bound=dtype[Any])
+DTS = TypeVar("DTS", covariant=True, bound=generic)
+S = TypeVar("S", bound=Any)
+ST = TypeVar("ST", bound=generic, covariant=True)
+
+class common: pass
+class generic(common): pass
+class dtype(Generic[DTS]): pass
+class array(common, Generic[S, DT]): pass
+Array = array[Any, dtype[ST]]
+
 [case testGenericTypeAliasesAny]
 from typing import TypeVar, Generic
 T = TypeVar('T')