Print trappable error types from other interfaces with their module path

crates/wit-bindgen/src/lib.rs

@@ -1227,7 +1227,10 @@ impl<'a> InterfaceGenerator<'a> {
  }
  }
 
- fn special_case_trappable_error(&self, results: &Results) -> Option<(&'a Result_, String)> {
+ fn special_case_trappable_error(
+ &self,
+ results: &Results,
+ ) -> Option<(&'a Result_, TypeId, String)> {
  // We fillin a special trappable error type in the case when a function has just one
  // result, which is itself a `result<a, e>`, and the `e` is *not* a primitive
  // (i.e. defined in std) type, and matches the typename given by the user.
@@ -1250,7 +1253,7 @@ impl<'a> InterfaceGenerator<'a> {
 
  let rust_type = self.trappable_errors.get(&error_typeid)?;
 
- Some((result, rust_type.clone()))
+ Some((result, error_typeid, rust_type.clone()))
  }
 
  fn generate_add_to_linker(&mut self, id: InterfaceId, name: &str) {
@@ -1431,7 +1434,9 @@ impl<'a> InterfaceGenerator<'a> {
  self.push_str(")");
  self.push_str(" -> ");
 
- if let Some((r, error_typename)) = self.special_case_trappable_error(&func.results) {
+ if let Some((r, error_id, error_typename)) =
+ self.special_case_trappable_error(&func.results)
+ {
  // Functions which have a single result `result<ok,err>` get special
  // cased to use the host_wasmtime_rust::Error<err>, making it possible
  // for them to trap or use `?` to propogate their errors
@@ -1442,6 +1447,12 @@ impl<'a> InterfaceGenerator<'a> {
  self.push_str("()");
  }
  self.push_str(",");
+ if let TypeOwner::Interface(id) = self.resolve.types[error_id].owner {
+ if let Some(path) = self.path_to_interface(id) {
+ self.push_str(&path);
+ self.push_str("::");
+ }
+ }
  self.push_str(&error_typename);
  self.push_str(">");
  } else {