gh-104572: Improve error messages for invalid constructs in PEP 695 contexts (#104573)

1 files changed, 62 insertions, 0 deletions

diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index f959bbb4400..477879db2fd 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -1877,6 +1877,68 @@ Invalid bytes literals:
         ^^^^^^^^^^^
    SyntaxError: bytes can only contain ASCII literal characters
 
+Invalid expressions in type scopes:
+
+   >>> type A[T: (x:=3)] = int
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within a TypeVar bound
+
+   >>> type A[T: (yield 3)] = int
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVar bound
+
+   >>> type A[T: (await 3)] = int
+   Traceback (most recent call last):
+      ...
+   SyntaxError: await expression cannot be used within a TypeVar bound
+
+   >>> type A[T: (yield from [])] = int
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVar bound
+
+   >>> type A = (x := 3)
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within a type alias
+
+   >>> type A = (yield 3)
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a type alias
+
+   >>> type A = (await 3)
+   Traceback (most recent call last):
+      ...
+   SyntaxError: await expression cannot be used within a type alias
+
+   >>> type A = (yield from [])
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a type alias
+
+   >>> class A[T]((x := 3)): ...
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within the definition of a generic
+
+   >>> class A[T]((yield 3)): ...
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within the definition of a generic
+
+   >>> class A[T]((await 3)): ...
+   Traceback (most recent call last):
+      ...
+   SyntaxError: await expression cannot be used within the definition of a generic
+
+   >>> class A[T]((yield from [])): ...
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within the definition of a generic
+
 """
 
 import re