Implement qualified flux defs and imports

crates/flux-desugar/locales/en-US.ftl

@@ -47,9 +47,16 @@ desugar_duplicate_definition =
     .label = `{$name}` redefined here
     .previous_definition = previous definition of `{$name}`
 
+desugar_ambiguous_name =
+    the name `{$name}` is ambiguous
+    .label = ambiguous name
+    .note = two different items named `{$name}` are in scope through glob imports
+    .first_candidate = `{$name}` could refer to the item imported here
+    .second_candidate = `{$name}` could also refer to the item imported here
+
 desugar_duplicate_param =
-    the name `{$name}` is already used as a parameter
-    .label = already used
+    identifier `{$name}` is bound more than once in this parameter list
+    .label = used as a parameter more than once
     .first_use = first use of `{$name}`
 
 desugar_unsupported_signature =
@@ -60,6 +67,10 @@ desugar_unresolved_name =
     cannot find {$kind} `{$name}` in this scope
     .label = not found in this scope
 
+desugar_unresolved_import =
+    unresolved import `{$name}`
+    .label = {$reason}
+
 desugar_invalid_unrefined_param =
     invalid use of refinement parameter
     .label = parameter `{$var}` refers to a type with no indices

crates/flux-desugar/src/desugar.rs

@@ -852,6 +852,7 @@ impl<'genv, 'tcx> FluxItemCtxt<'genv, 'tcx> {
                 let sort_decl = self.desugar_sort_decl(sort_decl);
                 fhir::FluxItem::SortDecl(self.genv.alloc(sort_decl))
             }
+            surface::FluxItem::Use(..) => bug!("unexpected use item"),
         }
     }
 

crates/flux-desugar/src/lib.rs

@@ -162,7 +162,8 @@ fn try_desugar_crate<'genv>(genv: GlobalEnv<'genv, '_>) -> Result<fhir::FluxItem
     let mut err: Option<ErrorGuaranteed> = None;
     for (parent, items) in &specs.flux_items_by_parent {
         for item in items {
-            let def_id = FluxLocalDefId::new(parent.def_id, item.name().name);
+            let Some(ident) = item.name() else { continue };
+            let def_id = FluxLocalDefId::new(parent.def_id, ident.name);
             FluxItemCtxt::with(genv, resolver_output, def_id, |cx| {
                 fhir.items.insert(def_id, cx.desugar_flux_item(item));
             })