gh-90949: Fix an "unused function" compiler warning introduced in GH-139234 (#139558)

Fix a compiler warning `-Wunused-function` after f04bea44c37793561d753dd4ca6e7cd658137553.

The `set_invalid_arg` function in `Modules/pyexpat.c` may be unused if the underlying Expat
version is less than 2.4.0.

diff --git a/Modules/pyexpat.c b/Modules/pyexpat.c
index 7f6d84ad8641ca0e17884e2e044823ac1599387c..9949e185dce9c7da5422f5679618f31f2197b7f4 100644 (file)
--- a/Modules/pyexpat.c
+++ b/Modules/pyexpat.c
@@ -198,12 +198,14 @@ set_error(pyexpat_state *state, xmlparseobject *self, enum XML_Error code)
     return NULL;
 }
 
+#if XML_COMBINED_VERSION >= 20400
 static PyObject *
 set_invalid_arg(pyexpat_state *state, xmlparseobject *self, const char *errmsg)
 {
     SET_XML_ERROR(state, self, XML_ERROR_INVALID_ARGUMENT, errmsg);
     return NULL;
 }
+#endif
 
 #undef SET_XML_ERROR