[3.13] gh-119933: Improve ``SyntaxError`` message for invalid type parameters expressions (GH-119976) (#120641)

(cherry picked from commit 4bf17c381fb7b465f0f26aecb94a6c54cf9be2d3)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

1 files changed, 100 insertions, 0 deletions

diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index 491f7fd..cdeb26a 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -2046,16 +2046,91 @@ Invalid expressions in type scopes:
    ...
    SyntaxError: Type parameter list cannot be empty
 
+   >>> def f[T: (x:=3)](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within a TypeVar bound
+
+   >>> def f[T: ((x:= 3), int)](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within a TypeVar constraint
+
+   >>> def f[T = ((x:=3))](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within a TypeVar default
+
+   >>> async def f[T: (x:=3)](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within a TypeVar bound
+
+   >>> async def f[T: ((x:= 3), int)](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within a TypeVar constraint
+
+   >>> async def f[T = ((x:=3))](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within a TypeVar default
+
    >>> type A[T: (x:=3)] = int
    Traceback (most recent call last):
       ...
    SyntaxError: named expression cannot be used within a TypeVar bound
 
+   >>> type A[T: ((x:= 3), int)] = int
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within a TypeVar constraint
+
+   >>> type A[T = ((x:=3))] = int
+   Traceback (most recent call last):
+      ...
+   SyntaxError: named expression cannot be used within a TypeVar default
+
+   >>> def f[T: (yield)](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVar bound
+
+   >>> def f[T: (int, (yield))](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVar constraint
+
+   >>> def f[T = (yield)](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVar default
+
+   >>> def f[*Ts = (yield)](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVarTuple default
+
+   >>> def f[**P = [(yield), int]](): pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a ParamSpec default
+
    >>> type A[T: (yield 3)] = int
    Traceback (most recent call last):
       ...
    SyntaxError: yield expression cannot be used within a TypeVar bound
 
+   >>> type A[T: (int, (yield 3))] = int
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVar constraint
+
+   >>> type A[T = (yield 3)] = int
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVar default
+
    >>> type A[T: (await 3)] = int
    Traceback (most recent call last):
       ...
@@ -2066,6 +2141,31 @@ Invalid expressions in type scopes:
       ...
    SyntaxError: yield expression cannot be used within a TypeVar bound
 
+   >>> class A[T: (yield 3)]: pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVar bound
+
+   >>> class A[T: (int, (yield 3))]: pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVar constraint
+
+   >>> class A[T = (yield)]: pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVar default
+
+   >>> class A[*Ts = (yield)]: pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a TypeVarTuple default
+
+   >>> class A[**P = [(yield), int]]: pass
+   Traceback (most recent call last):
+      ...
+   SyntaxError: yield expression cannot be used within a ParamSpec default
+
    >>> type A = (x := 3)
    Traceback (most recent call last):
       ...