test(cpythontest): PyUnicode_GetLength(Py_ssize_t=64位) 改用 t.CPtrDiffT 接收，并校正 cpython.vp 三处应为 64 位的返回类型

CPythonTest/App/cpython.vp

@@ -109,8 +109,8 @@ extern def PyLong_FromSize_t(v: sizet) -> PyObject*
 extern def PyLong_FromDouble(v: double) -> PyObject*
 extern def PyLong_AsLong(obj: PyObject*) -> int
 extern def PyLong_AsUnsignedLong(obj: PyObject*) -> t.CUnsignedLong
-extern def PyLong_AsLongLong(obj: PyObject*) -> t.CLong
-extern def PyLong_AsUnsignedLongLong(obj: PyObject*) -> t.CUnsignedLong
+extern def PyLong_AsLongLong(obj: PyObject*) -> t.CLongLong
+extern def PyLong_AsUnsignedLongLong(obj: PyObject*) -> t.CUnsignedLongLong
 extern def PyLong_AsDouble(obj: PyObject*) -> double
 extern def PyLong_AsSsize_t(obj: PyObject*) -> t.CPtrDiffT
 extern def PyLong_AsSize_t(obj: PyObject*) -> sizet
@@ -220,7 +220,7 @@ extern def PyObject_IsTrue(obj: PyObject*) -> int
 extern def PyObject_Not(obj: PyObject*) -> int
 extern def PyObject_RichCompare(o1: PyObject*, o2: PyObject*, opid: int) -> PyObject*
 extern def PyObject_RichCompareBool(o1: PyObject*, o2: PyObject*, opid: int) -> int
-extern def PyObject_Hash(obj: PyObject*) -> t.CLong
+extern def PyObject_Hash(obj: PyObject*) -> t.CPtrDiffT
 extern def PyObject_Length(obj: PyObject*) -> sizet
 extern def PyObject_GetItem(obj: PyObject*, key: PyObject*) -> PyObject*
 extern def PyObject_SetItem(obj: PyObject*, key: PyObject*, val: PyObject*) -> int

CPythonTest/App/main.vp

@@ -68,7 +68,9 @@ def test_string_operations():
     printf("  PyUnicode_FromString -> %s\n", utf8)
 
     # String length
-    length: CLong = cpython.PyUnicode_GetLength(py_s1)
+    # PyUnicode_GetLength 返回 CPython 的 Py_ssize_t（= ptrdiff_t，64 位）；CLong 在本目标
+    # (x86_64-pc-windows-gnu / LLP64) 只有 32 位，用 CLong 接收会触发「隐式窄化禁止」。
+    length: t.CPtrDiffT = cpython.PyUnicode_GetLength(py_s1)
     testcheck.check(length == 13, "GetLength == 13", "GetLength == 13")
 
     # String concat