interpreterbase: Allow passing an extra message in feature/deprecation warnings

The intended use it to tell people the new thing to do.

mesonbuild/interpreterbase.py

@@ -220,9 +220,10 @@ class FeatureCheckBase(metaclass=abc.ABCMeta):
     # This will be overwritten by the subclasses by necessity
     feature_registry = {}  # type: T.ClassVar[T.Dict[str, T.Dict[str, T.Set[str]]]]
 
-    def __init__(self, feature_name: str, version: str):
+    def __init__(self, feature_name: str, version: str, extra_message: T.Optional[str] = None):
         self.feature_name = feature_name  # type: str
         self.feature_version = version    # type: str
+        self.extra_message = extra_message or ''  # type: str
 
     @staticmethod
     def get_target_version(subproject: str) -> str:
@@ -302,8 +303,15 @@ class FeatureNew(FeatureCheckBase):
         return 'Project specifies a minimum meson_version \'{}\' but uses features which were added in newer versions:'.format(tv)
 
     def log_usage_warning(self, tv: str) -> None:
-        mlog.warning('Project targeting \'{}\' but tried to use feature introduced '
-                     'in \'{}\': {}'.format(tv, self.feature_version, self.feature_name))
+        args = [
+            'Project targeting', "'{}'".format(tv),
+            'but tried to use feature introduced in',
+            "'{}':".format(self.feature_version),
+            '{}.'.format(self.feature_name),
+        ]
+        if self.extra_message:
+            args.append(self.extra_message)
+        mlog.warning(*args)
 
 class FeatureDeprecated(FeatureCheckBase):
     """Checks for deprecated features"""
@@ -323,9 +331,15 @@ class FeatureDeprecated(FeatureCheckBase):
         return 'Deprecated features used:'
 
     def log_usage_warning(self, tv: str) -> None:
-        mlog.deprecation('Project targeting \'{}\' but tried to use feature '
-                         'deprecated since \'{}\': {}'
-                         ''.format(tv, self.feature_version, self.feature_name))
+        args = [
+            'Project targeting', "'{}'".format(tv),
+            'but tried to use feature deprecated since',
+            "'{}':".format(self.feature_version),
+            '{}.'.format(self.feature_name),
+        ]
+        if self.extra_message:
+            args.append(self.extra_message)
+        mlog.warning(*args)
 
 
 class FeatureCheckKwargsBase:

run_project_tests.py

@@ -417,6 +417,7 @@ def _compare_output(expected: T.List[T.Dict[str, str]], output: str, desc: str)
                     match = bool(re.match(expected, actual))
                 else:
                     match = (expected == actual)
+                    print(actual)
                 if match:
                     how, expected = next_expected(i)
 

test cases/warning/1 version for string div/test.json

@@ -2,7 +2,7 @@
   "stdout": [
     {
       "comment": "literal '/' appears in output, irrespective of os.path.sep, as that's the operator",
-      "line": "WARNING: Project targeting '>=0.48.0' but tried to use feature introduced in '0.49.0': / with string arguments"
+      "line": "WARNING: Project targeting '>=0.48.0' but tried to use feature introduced in '0.49.0': / with string arguments."
     }
   ]
 }