Emit Y020 for quoted annotations used in TypeVar constraints (#407)

Author: AlexWaygood

CHANGELOG.md

@@ -31,6 +31,8 @@ Bugfixes:
   TypeVars/ParamSpecs/TypeAliases/TypedDicts/Protocols if the object in question had
   multiple definitions in the same file (e.g. across two branches of an `if
   sys.version_info >= (3, 10)` check). This bug has now been fixed.
+* Y020 was previously not emitted if quoted annotations were used in TypeVar
+  constraints. This bug has now been fixed.
 
 Other changes:
 * flake8-pyi no longer supports being run on Python 3.7.

pyi.py

@@ -1137,15 +1137,15 @@ def visit_Call(self, node: ast.Call) -> None:
         ):
             return self.error(node, Y056.format(method=f".{function.attr}()"))
 
-        # String literals can appear in positional arguments for
-        # TypeVar definitions.
-        with self.string_literals_allowed.enabled():
-            for arg in node.args:
-                self.visit(arg)
-        # But in keyword arguments they're most likely TypeVar bounds,
+        # String literals can appear as the first positional argument for
+        # TypeVar/ParamSpec/TypeVarTuple/NamedTuple/TypedDict/NewType definitions, etc.
+        if node.args:
+            with self.string_literals_allowed.enabled():
+                self.visit(node.args[0])
+        # But in other arguments they're most likely TypeVar bounds,
         # which should not be quoted.
-        for kw in node.keywords:
-            self.visit(kw)
+        for arg in chain(node.args[1:], node.keywords):
+            self.visit(arg)
 
     def visit_Constant(self, node: ast.Constant) -> None:
         if isinstance(node.value, str) and not self.string_literals_allowed.active:

tests/quotes.pyi

@@ -1,6 +1,6 @@
 import sys
 import typing
-from typing import Annotated, Literal, TypeAlias, TypeVar
+from typing import Annotated, Literal, NewType, TypeAlias, TypeVar
 
 import typing_extensions
 
@@ -15,6 +15,16 @@ __slots__ = ('foo',)  # Y052 Need type annotation for "__slots__"
 def f(x: "int"): ...  # Y020 Quoted annotations should never be used in stubs
 def g(x: list["int"]): ...  # Y020 Quoted annotations should never be used in stubs
 _T = TypeVar("_T", bound="int")  # Y020 Quoted annotations should never be used in stubs
+_T2 = TypeVar("_T", bound=int)
+_S = TypeVar("_S")
+_U = TypeVar("_U", "int", "str")  # Y020 Quoted annotations should never be used in stubs  # Y020 Quoted annotations should never be used in stubs
+_U2 = TypeVar("_U", int, str)
+
+# This is invalid, but type checkers will flag it, so we don't need to
+_V = TypeVar()
+
+def make_sure_those_typevars_arent_flagged_as_unused(a: _T, b: _T2, c: _S, d: _U, e: _U2, f: _V) -> tuple[_T, _T2, _S, _U, _U2, _V]: ...
+
 def h(w: Literal["a", "b"], x: typing.Literal["c"], y: typing_extensions.Literal["d"], z: _T) -> _T: ...
 
 def i(x: Annotated[int, "lots", "of", "strings"], b: typing.Annotated[str, "more", "strings"]) -> None:
@@ -60,3 +70,6 @@ class DocstringAndPass:
 k = ""  # Y052 Need type annotation for "k"
 el = r""  # Y052 Need type annotation for "el"
 m = u""  # Y052 Need type annotation for "m"
+
+_N = NewType("_N", int)
+_NBad = NewType("_N", "int")  # Y020 Quoted annotations should never be used in stubs