3 files changed, 20 insertions, 4 deletions
diff --git a/src/makefile/input.rs b/src/makefile/input.rs
index 2f8de49..1757222 100644
--- a/src/makefile/input.rs
+++ b/src/makefile/input.rs
@@ -703,6 +703,7 @@ impl<'a, 'parent, R: BufRead> MakefileReader<'a, 'parent, R> {
         FinishedMakefileReader {
             inference_rules: self.inference_rules,
             macros: self.macros.data,
+            macro_exports: self.macros.exported,
             targets: self.targets,
             first_non_special_target: self.first_non_special_target,
             failed_includes: self.failed_includes,
@@ -711,7 +712,7 @@ impl<'a, 'parent, R: BufRead> MakefileReader<'a, 'parent, R> {
 
     fn extend(&mut self, new: FinishedMakefileReader) {
         self.inference_rules.extend(new.inference_rules);
-        self.macros.extend(new.macros);
+        self.macros.extend(new.macros, new.macro_exports);
         self.targets.extend(new.targets);
         if self.first_non_special_target.is_none() {
             self.first_non_special_target = new.first_non_special_target;
@@ -723,6 +724,7 @@ impl<'a, 'parent, R: BufRead> MakefileReader<'a, 'parent, R> {
 pub struct FinishedMakefileReader {
     pub inference_rules: Vec<InferenceRule>,
     pub macros: HashMap<String, Macro>,
+    pub macro_exports: ExportConfig,
     pub targets: HashMap<String, Target>,
     pub first_non_special_target: Option<String>,
     pub failed_includes: Vec<String>,
diff --git a/src/makefile/macro.rs b/src/makefile/macro.rs
index 5e7ea9c..65a87d1 100644
--- a/src/makefile/macro.rs
+++ b/src/makefile/macro.rs
@@ -36,7 +36,7 @@ pub trait LookupInternal: for<'a> Fn(&'a str) -> Result<String> {}
 impl<F: for<'a> Fn(&'a str) -> Result<String>> LookupInternal for F {}
 
 #[cfg(feature = "full")]
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub enum ExportConfig {
     Only(HashSet<String>),
     AllBut(HashSet<String>),
@@ -183,7 +183,21 @@ impl<'parent, 'lookup> Set<'parent, 'lookup> {
             .or_else(|| self.parent.and_then(|p| p.get(name).cloned()))
     }
 
-    pub fn extend(&mut self, other: HashMap<String, Macro>) {
+    pub fn extend(&mut self, other: HashMap<String, Macro>, other_exports: ExportConfig) {
+        match (&mut self.exported, other_exports) {
+            (ExportConfig::Only(se), ExportConfig::Only(oe)) => {
+                se.extend(oe);
+            }
+            (ExportConfig::AllBut(sne), ExportConfig::AllBut(one)) => {
+                sne.extend(one);
+            }
+            (ExportConfig::Only(se), ExportConfig::AllBut(one)) => {
+                se.extend(other.keys().cloned().filter(|name| !one.contains(name)));
+            }
+            (ExportConfig::AllBut(sne), ExportConfig::Only(oe)) => {
+                sne.extend(other.keys().cloned().filter(|name| !oe.contains(name)));
+            }
+        }
         self.data.extend(other);
     }
 
diff --git a/src/makefile/mod.rs b/src/makefile/mod.rs
index f17ba64..cdf9d0b 100644
--- a/src/makefile/mod.rs
+++ b/src/makefile/mod.rs
@@ -110,7 +110,7 @@ impl<'a> Makefile<'a> {
 
     pub fn extend(&mut self, new: FinishedMakefileReader) -> Result<()> {
         self.inference_rules.extend(new.inference_rules);
-        self.macros.extend(new.macros);
+        self.macros.extend(new.macros, new.macro_exports);
         self.targets.borrow_mut().extend(
             new.targets
                 .into_iter()