Remove non-geo phone numbers from the SplitPhoneNumberWidget

The COUNTRY_CODE_TO_REGION_CODE dict contains values that are not
specific to a region code: the COUNTRY_CODES_FOR_NON_GEO_REGIONS. These
country codes are international, and are not a good fit for the
SplitPhoneNumberWidget, which offers to select a region, then fill in
the national number.

phonenumber_field/formfields.py

@@ -6,7 +6,7 @@
 from django.utils import translation
 from django.utils.text import format_lazy
 from django.utils.translation import pgettext, pgettext_lazy
-from phonenumbers import COUNTRY_CODE_TO_REGION_CODE
+from phonenumbers import COUNTRY_CODE_TO_REGION_CODE, COUNTRY_CODES_FOR_NON_GEO_REGIONS
 
 from phonenumber_field import widgets
 from phonenumber_field.phonenumber import to_python, validate_region
@@ -17,10 +17,13 @@
 except ModuleNotFoundError:
     babel = None  # type: ignore
 
+GEO_COUNTRY_CODE_TO_REGION_CODE = COUNTRY_CODE_TO_REGION_CODE.copy()
+for country_code in COUNTRY_CODES_FOR_NON_GEO_REGIONS:
+    del GEO_COUNTRY_CODE_TO_REGION_CODE[country_code]
 # ISO 3166-1 alpha-2 to national prefix
 REGION_CODE_TO_COUNTRY_CODE = {
     region_code: country_code
-    for country_code, region_codes in COUNTRY_CODE_TO_REGION_CODE.items()
+    for country_code, region_codes in GEO_COUNTRY_CODE_TO_REGION_CODE.items()
     for region_code in region_codes
 }
 

tests/test_formfields.py

@@ -7,6 +7,7 @@
 from django.test import SimpleTestCase, override_settings
 from django.utils import translation
 from django.utils.functional import lazy
+from phonenumbers import COUNTRY_CODES_FOR_NON_GEO_REGIONS
 
 from phonenumber_field.formfields import PhoneNumberField, SplitPhoneNumberField
 from phonenumber_field.phonenumber import PhoneNumber
@@ -175,6 +176,8 @@ class TestForm(forms.Form):
         rendered = str(TestForm())
         self.assertIn('<option value="" selected>---------</option>', rendered)
         self.assertIn('<option value="CN">China +86</option>', rendered)
+        for prefix in COUNTRY_CODES_FOR_NON_GEO_REGIONS:
+            self.assertNotIn(f"+{prefix}", rendered)
 
     def test_initial(self):
         class TestForm(forms.Form):