fix a crash in compiling external references in modules

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)
  }