Add feature.to_string()

This was previously accepted in
https://github.com/mesonbuild/meson/pull/6922, but the author never came
around to finish it, so here is everything that should be needed to add
the feature.

docs/markdown/snippets/feature_to_string.md

@@ -0,0 +1,3 @@
+## Features now have a `to_string()` method
+
+The method will return one of `auto`, `enabled`, or `disabled`.

docs/yaml/objects/feature.yaml

@@ -163,3 +163,8 @@ methods:
       type: str
       default: "''"
       description: The error message to print if the check fails
+
+- name: to_string
+  returns: str
+  since: 1.3.0
+  description: Returns the value of the feature option as a string.

mesonbuild/interpreter/interpreterobjects.py

@@ -102,6 +102,7 @@ class FeatureOptionHolder(ObjectHolder[coredata.UserFeatureOption]):
                              'enable_auto_if': self.enable_auto_if_method,
                              'disable_if': self.disable_if_method,
                              'enable_if': self.enable_if_method,
+                             'to_string': self.to_string_method,
                              })
 
     @property
@@ -197,6 +198,12 @@ class FeatureOptionHolder(ObjectHolder[coredata.UserFeatureOption]):
     def enable_auto_if_method(self, args: T.Tuple[bool], kwargs: TYPE_kwargs) -> coredata.UserFeatureOption:
         return self.as_enabled() if self.value == 'auto' and args[0] else copy.deepcopy(self.held_object)
 
+    @FeatureNew('feature_option.to_string()', '1.3.0')
+    @noKwargs
+    @noPosargs
+    def to_string_method(self, args: T.List[TYPE_var], kwargs: TYPE_kwargs) -> str:
+        return self.held_object.value
+
 
 class RunProcess(MesonInterpreterObject):
 

test cases/common/192 feature option/meson.build

@@ -22,6 +22,7 @@ assert(required_opt.disable_auto_if(true).enabled(), 'Should be enabled option')
 assert(required_opt.disable_auto_if(false).enabled(), 'Should be enabled option')
 assert(required_opt.enable_auto_if(true).enabled(), 'Should be enabled option')
 assert(required_opt.enable_auto_if(false).enabled(), 'Should be enabled option')
+assert(required_opt.to_string() == 'enabled', 'Should be enabled option')
 
 assert(not optional_opt.enabled(), 'Should be auto option')
 assert(not optional_opt.disabled(), 'Should be auto option')
@@ -37,6 +38,7 @@ assert(optional_opt.disable_auto_if(true).disabled(), 'Should be disabled auto o
 assert(optional_opt.disable_auto_if(false).auto(), 'Should be auto option')
 assert(optional_opt.enable_auto_if(true).enabled(), 'Should be disabled auto option')
 assert(optional_opt.enable_auto_if(false).auto(), 'Should be auto option')
+assert(optional_opt.to_string() == 'auto', 'Should be auto option')
 
 assert(not disabled_opt.enabled(), 'Should be disabled option')
 assert(disabled_opt.disabled(), 'Should be disabled option')
@@ -51,6 +53,7 @@ assert(disabled_opt.disable_auto_if(true).disabled(), 'Should be disabled option
 assert(disabled_opt.disable_auto_if(false).disabled(), 'Should be disabled option')
 assert(disabled_opt.enable_auto_if(true).disabled(), 'Should be disabled option')
 assert(disabled_opt.enable_auto_if(false).disabled(), 'Should be disabled option')
+assert(disabled_opt.to_string() == 'disabled', 'Should be disabled option')
 
 dep = dependency('threads', required : required_opt)
 assert(dep.found(), 'Should find required "threads" dep')