1 files changed, 23 insertions, 16 deletions

diff --git a/src/resolver.rs b/src/resolver.rs
index 2b49055..8d3a16d 100644
--- a/src/resolver.rs
+++ b/src/resolver.rs
@@ -43,12 +43,20 @@ impl Resolver {
         let source_id = self.source_units.len();
         use std::mem::take;
 
-        info!("Including source file at {:?}", source_unit.main.path);
-        self.include_symbols(take(&mut source_unit.main.symbols), source_id, SourceRole::Main);
+        info!("Including source unit at {:?}", source_unit.main.path);
+        if let Some(symbols) = &mut source_unit.main.symbols {
+            self.include_symbols(take(symbols), source_id, SourceRole::Main);
+        }
         if let Some(head) = &mut source_unit.head {
-            self.include_symbols(take(&mut head.symbols), source_id, SourceRole::Head); }
+            if let Some(symbols) = &mut head.symbols {
+                self.include_symbols(take(symbols), source_id, SourceRole::Head);
+            }
+        }
         if let Some(tail) = &mut source_unit.tail {
-            self.include_symbols(take(&mut tail.symbols), source_id, SourceRole::Tail); }
+            if let Some(symbols) = &mut tail.symbols {
+                self.include_symbols(take(symbols), source_id, SourceRole::Tail);
+            }
+        }
 
         match parent_id {
             Some(parent_id) => match self.source_units.get_mut(parent_id) {
@@ -153,19 +161,18 @@ impl Resolver {
     /// Return the ID of a source unit that contains an unresolved reference
     /// to a symbol defined by this unit.
     fn unit_resolved_by_unit(&self, source_unit: &SourceUnit) -> Option<usize> {
-        if let Some(id) = self.unit_resolved_by_symbol(&source_unit.main.symbols) {
-            return Some(id);
-        }
-        if let Some(head) = &source_unit.head {
-            if let Some(id) = self.unit_resolved_by_symbol(&head.symbols) {
-                return Some(id);
-            }
-        }
-        if let Some(tail) = &source_unit.tail {
-            if let Some(id) = self.unit_resolved_by_symbol(&tail.symbols) {
-                return Some(id);
-            }
+        macro_rules! return_resolved_unit {
+            ($file:expr) => {
+                if let Some(symbols) = &$file.symbols {
+                    if let Some(id) = self.unit_resolved_by_symbol(&symbols) {
+                        return Some(id);
+                    }
+                }
+            };
         }
+        return_resolved_unit!(&source_unit.main);
+        if let Some(head) = &source_unit.head { return_resolved_unit!(&head) }
+        if let Some(tail) = &source_unit.tail { return_resolved_unit!(&tail) }
         return None;
     }