implement rule-specific macros for targets

1 files changed, 6 insertions, 0 deletions

diff --git a/src/makefile/macro_scope.rs b/src/makefile/macro_scope.rs
index ba9b6cf..c03870f 100644
--- a/src/makefile/macro_scope.rs
+++ b/src/makefile/macro_scope.rs
@@ -43,6 +43,12 @@ impl<'a> MacroScope for LookupInternal<'a> {
     }
 }
 
+impl<T: MacroScope> MacroScope for Option<&T> {
+    fn get(&self, name: &str) -> Option<Cow<Macro>> {
+        self.as_ref().and_then(|value| value.get(name))
+    }
+}
+
 // warning on undefined macros is useful but can get repetitive fast
 lazy_static! {
     static ref WARNINGS_EMITTED: RwLock<HashSet<String>> = Default::default();