Add compatibility method to warn for future underscore change

setuptools/dist.py

@@ -598,7 +598,7 @@ def _parse_config_files(self, filenames=None):  # noqa: C901
                         continue
 
                     val = parser.get(section, opt)
-                    opt = opt.replace('-', '_')
+                    opt = self.dash_to_underscore_warning(opt)
                     opt_dict[opt] = (filename, val)
 
             # Make the ConfigParser forget everything (so we retain
@@ -623,6 +623,21 @@ def _parse_config_files(self, filenames=None):  # noqa: C901
             except ValueError as e:
                 raise DistutilsOptionError(e) from e
 
+    def dash_to_underscore_warning(self, opt):
+        if opt in (
+            'home-page', 'download-url', 'author-email',
+            'maintainer-email', 'long-description', 'build-base',
+            'project-urls', 'license-file', 'license-files',
+            'long-description-content-type',
+        ):
+            underscore_opt = opt.replace('-', '_')
+            warnings.warn(
+                "Usage of dash-separated '%s' will not be supported in future "
+                "versions. Please use the underscore name '%s' instead"
+                % (opt, underscore_opt))
+            return underscore_opt
+        return opt
+
     # FIXME: 'Distribution._set_command_options' is too complex (14)
     def _set_command_options(self, command_obj, option_dict=None):  # noqa: C901
         """