Compute layout with spans for better cycle errors in coroutines

Author: compiler-errors

compiler/rustc_ast_lowering/src/expr.rs

@@ -792,8 +792,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // debuggers and debugger extensions expect it to be called `__awaitee`. They use
         // this name to identify what is being awaited by a suspended async functions.
         let awaitee_ident = Ident::with_dummy_span(sym::__awaitee);
-        let (awaitee_pat, awaitee_pat_hid) =
-            self.pat_ident_binding_mode(span, awaitee_ident, hir::BindingAnnotation::MUT);
+        let (awaitee_pat, awaitee_pat_hid) = self.pat_ident_binding_mode(
+            gen_future_span,
+            awaitee_ident,
+            hir::BindingAnnotation::MUT,
+        );
 
         let task_context_ident = Ident::with_dummy_span(sym::_task_context);
 

compiler/rustc_ty_utils/src/layout.rs

@@ -740,11 +740,11 @@ fn coroutine_layout<'tcx>(
     };
     let tag_layout = cx.tcx.mk_layout(LayoutS::scalar(cx, tag));
 
-    let promoted_layouts = ineligible_locals
-        .iter()
-        .map(|local| subst_field(info.field_tys[local].ty))
-        .map(|ty| Ty::new_maybe_uninit(tcx, ty))
-        .map(|ty| Ok(cx.layout_of(ty)?.layout));
+    let promoted_layouts = ineligible_locals.iter().map(|local| {
+        let field_ty = subst_field(info.field_tys[local].ty);
+        let uninit_ty = Ty::new_maybe_uninit(tcx, field_ty);
+        Ok(cx.spanned_layout_of(uninit_ty, info.field_tys[local].source_info.span)?.layout)
+    });
     let prefix_layouts = args
         .as_coroutine()
         .prefix_tys()