fix a crash in compiling external references in modules

Author: kaikalii

src/assembly.rs

@@ -46,8 +46,20 @@ impl From<&Assembly> for Assembly {
 
 impl Assembly {
     /// Get the instructions of a function slice
+    #[track_caller]
     pub fn instrs(&self, slice: FuncSlice) -> &[Instr] {
-        &self.instrs[slice.start..slice.end()]
+        let end = slice.end();
+        assert!(
+            slice.start <= self.instrs.len(),
+            "Func slice start {} out of bounds",
+            slice.start
+        );
+        assert!(
+            slice.end() <= self.instrs.len(),
+            "Func slice end {} out of bounds",
+            end
+        );
+        &self.instrs[slice.start..end]
     }
     /// Get the mutable instructions of a function slice
     pub fn instrs_mut(&mut self, slice: FuncSlice) -> &mut [Instr] {

src/compile/binding.rs

@@ -268,8 +268,8 @@ impl Compiler {
                 );
                 if let [Instr::PushFunc(f)] = instrs.as_slice() {
                     // Binding is a single inline function
-                    sig = f.signature();
-                    let func = make_fn(f.instrs(&self.asm).into(), f.signature(), self);
+                    let mut func = f.clone();
+                    func.id = FunctionId::Named(name.clone());
                     self.compile_bind_function(&name, local, func, spandex, comment.as_deref())?;
                 } else if sig == (0, 1) && !is_setinv && !is_setund {
                     if let &[Instr::Prim(Primitive::Tag, span)] = instrs.as_slice() {

src/compile/mod.rs

@@ -642,7 +642,7 @@ code:
         if len > 1 {
             (self.asm.instrs).push(Instr::Comment(format!("({id}").into()));
         }
-        let start = self.asm.instrs.len();
+        let start = if len == 0 { 0 } else { self.asm.instrs.len() };
         let mut hasher = DefaultHasher::new();
         instrs.hash(&mut hasher);
         let hash = hasher.finish();

src/function.rs

@@ -817,6 +817,7 @@ impl Function {
         self.slice
     }
     /// Get the function's instructions
+    #[track_caller]
     pub fn instrs<'a>(&self, asm: &'a Assembly) -> &'a [Instr] {
         asm.instrs(self.slice)
     }