Add basic code for feature version detection:

* store target version
* Add empty method decorator

mesonbuild/coredata.py

@@ -23,6 +23,7 @@ import ast
 import argparse
 
 version = '0.47.0.dev1'
+target_version = ''
 backendlist = ['ninja', 'vs', 'vs2010', 'vs2015', 'vs2017', 'xcode']
 
 default_yielding = False

mesonbuild/interpreter.py

@@ -2285,6 +2285,7 @@ to directly access options of other subprojects.''')
         if 'meson_version' in kwargs:
             cv = coredata.version
             pv = kwargs['meson_version']
+            coredata.target_version = pv
             if not mesonlib.version_compare(cv, pv):
                 raise InterpreterException('Meson version is %s but project requires %s.' % (cv, pv))
         self.build.projects[self.subproject] = proj_name

mesonbuild/interpreterbase.py

@@ -17,6 +17,7 @@
 
 from . import mparser, mesonlib, mlog
 from . import environment, dependencies
+from . import coredata
 
 import os, copy, re, types
 from functools import wraps
@@ -123,6 +124,22 @@ class permittedKwargs:
             return f(*wrapped_args, **wrapped_kwargs)
         return wrapped
 
+class featureVersion:
+    """Checks for newer/deprecated features"""
+
+    def __init__(self, feature_name, wanted_version):
+        self.feature_name = feature_name
+        self.wanted_version = wanted_version
+
+    def __call__(self, f):
+        @wraps(f)
+        def wrapped(*wrapped_args, **wrapped_kwargs):
+            tv = coredata.target_version
+            if tv == '':
+                return
+            return f(*wrapped_args, **wrapped_kwargs)
+        return wrapped
+
 class InterpreterException(mesonlib.MesonException):
     pass