Fix daemon crashes on generic methods (#13551)

Fix #11795 

The fix is straightforward (but ideally generic callables should be normalized in the first place, e.g. by better use of namespaces).

mypy/server/astdiff.py

@@ -52,9 +52,10 @@ class level -- these are handled at attribute level (say, 'mod.Cls.method'
 
 from __future__ import annotations
 
-from typing import Sequence, Tuple
+from typing import Sequence, Tuple, cast
 from typing_extensions import TypeAlias as _TypeAlias
 
+from mypy.expandtype import expand_type
 from mypy.nodes import (
     UNBOUND_IMPORTED,
     Decorator,
@@ -88,6 +89,8 @@ class level -- these are handled at attribute level (say, 'mod.Cls.method'
     TypeAliasType,
     TypedDictType,
     TypeType,
+    TypeVarId,
+    TypeVarLikeType,
     TypeVarTupleType,
     TypeVarType,
     TypeVisitor,
@@ -388,7 +391,8 @@ def visit_parameters(self, typ: Parameters) -> SnapshotItem:
         )
 
     def visit_callable_type(self, typ: CallableType) -> SnapshotItem:
-        # FIX generics
+        if typ.is_generic():
+            typ = self.normalize_callable_variables(typ)
         return (
             "CallableType",
             snapshot_types(typ.arg_types),
@@ -397,8 +401,26 @@ def visit_callable_type(self, typ: CallableType) -> SnapshotItem:
             tuple(typ.arg_kinds),
             typ.is_type_obj(),
             typ.is_ellipsis_args,
+            snapshot_types(typ.variables),
         )
 
+    def normalize_callable_variables(self, typ: CallableType) -> CallableType:
+        """Normalize all type variable ids to run from -1 to -len(variables)."""
+        tvs = []
+        tvmap: dict[TypeVarId, Type] = {}
+        for i, v in enumerate(typ.variables):
+            tid = TypeVarId(-1 - i)
+            if isinstance(v, TypeVarType):
+                tv: TypeVarLikeType = v.copy_modified(id=tid)
+            elif isinstance(v, TypeVarTupleType):
+                tv = v.copy_modified(id=tid)
+            else:
+                assert isinstance(v, ParamSpecType)
+                tv = v.copy_modified(id=tid)
+            tvs.append(tv)
+            tvmap[v.id] = tv
+        return cast(CallableType, expand_type(typ, tvmap)).copy_modified(variables=tvs)
+
     def visit_tuple_type(self, typ: TupleType) -> SnapshotItem:
         return ("TupleType", snapshot_types(typ.items))
 

mypy/types.py

@@ -517,15 +517,23 @@ def __init__(
     @staticmethod
     def new_unification_variable(old: TypeVarType) -> TypeVarType:
         new_id = TypeVarId.new(meta_level=1)
+        return old.copy_modified(id=new_id)
+
+    def copy_modified(
+        self,
+        values: Bogus[list[Type]] = _dummy,
+        upper_bound: Bogus[Type] = _dummy,
+        id: Bogus[TypeVarId | int] = _dummy,
+    ) -> TypeVarType:
         return TypeVarType(
-            old.name,
-            old.fullname,
-            new_id,
-            old.values,
-            old.upper_bound,
-            old.variance,
-            old.line,
-            old.column,
+            self.name,
+            self.fullname,
+            self.id if id is _dummy else id,
+            self.values if values is _dummy else values,
+            self.upper_bound if upper_bound is _dummy else upper_bound,
+            self.variance,
+            self.line,
+            self.column,
         )
 
     def accept(self, visitor: TypeVisitor[T]) -> T:
@@ -616,16 +624,7 @@ def __init__(
     @staticmethod
     def new_unification_variable(old: ParamSpecType) -> ParamSpecType:
         new_id = TypeVarId.new(meta_level=1)
-        return ParamSpecType(
-            old.name,
-            old.fullname,
-            new_id,
-            old.flavor,
-            old.upper_bound,
-            line=old.line,
-            column=old.column,
-            prefix=old.prefix,
-        )
+        return old.copy_modified(id=new_id)
 
     def with_flavor(self, flavor: int) -> ParamSpecType:
         return ParamSpecType(
@@ -737,8 +736,16 @@ def __eq__(self, other: object) -> bool:
     @staticmethod
     def new_unification_variable(old: TypeVarTupleType) -> TypeVarTupleType:
         new_id = TypeVarId.new(meta_level=1)
+        return old.copy_modified(id=new_id)
+
+    def copy_modified(self, id: Bogus[TypeVarId | int] = _dummy) -> TypeVarTupleType:
         return TypeVarTupleType(
-            old.name, old.fullname, new_id, old.upper_bound, line=old.line, column=old.column
+            self.name,
+            self.fullname,
+            self.id if id is _dummy else id,
+            self.upper_bound,
+            line=self.line,
+            column=self.column,
         )
 
 

test-data/unit/fine-grained.test

@@ -9969,3 +9969,65 @@ m.py:9: note:     Expected:
 m.py:9: note:         def update() -> bool
 m.py:9: note:     Got:
 m.py:9: note:         def update() -> str
+
+[case testBoundGenericMethodFine]
+import main
+[file main.py]
+import lib
+[file main.py.3]
+import lib
+reveal_type(lib.foo(42))
+[file lib/__init__.pyi]
+from lib import context
+foo = context.test.foo
+[file lib/context.pyi]
+from typing import TypeVar
+import lib.other
+
+T = TypeVar("T")
+class Test:
+    def foo(self, x: T, n: lib.other.C = ...) -> T: ...
+test: Test
+
+[file lib/other.pyi]
+class C: ...
+[file lib/other.pyi.2]
+class B: ...
+class C(B): ...
+[out]
+==
+==
+main.py:2: note: Revealed type is "builtins.int"
+
+[case testBoundGenericMethodParamSpecFine]
+import main
+[file main.py]
+import lib
+[file main.py.3]
+from typing import Callable
+import lib
+f: Callable[[], int]
+reveal_type(lib.foo(f))
+[file lib/__init__.pyi]
+from lib import context
+foo = context.test.foo
+[file lib/context.pyi]
+from typing_extensions import ParamSpec
+from typing import Callable
+import lib.other
+
+P = ParamSpec("P")
+class Test:
+    def foo(self, x: Callable[P, int], n: lib.other.C = ...) -> Callable[P, str]: ...
+test: Test
+
+[file lib/other.pyi]
+class C: ...
+[file lib/other.pyi.2]
+class B: ...
+class C(B): ...
+[builtins fixtures/dict.pyi]
+[out]
+==
+==
+main.py:4: note: Revealed type is "def () -> builtins.str"