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()

tests/ui/type-alias-impl-trait/indirect-recursion-issue-112047.rs

@@ -1,6 +1,5 @@
 // edition: 2021
 // build-fail
-//~^^ ERROR cycle detected when computing layout of
 
 #![feature(impl_trait_in_assoc_type)]
 
@@ -21,6 +20,7 @@ impl Recur for () {
 
     fn recur(self) -> Self::Recur {
         async move { recur(self).await; }
+        //~^^ ERROR cycle detected when computing layout of
     }
 }
 

tests/ui/type-alias-impl-trait/indirect-recursion-issue-112047.stderr

@@ -1,14 +1,22 @@
-error[E0391]: cycle detected when computing layout of `{async block@$DIR/indirect-recursion-issue-112047.rs:23:9: 23:42}`
+error[E0391]: cycle detected when computing layout of `{async block@$DIR/indirect-recursion-issue-112047.rs:22:9: 22:42}`
+  --> $DIR/indirect-recursion-issue-112047.rs:22:22
    |
-   = note: ...which requires computing layout of `core::mem::maybe_uninit::MaybeUninit<{async fn body@$DIR/indirect-recursion-issue-112047.rs:15:31: 17:2}>`...
-   = note: ...which requires computing layout of `core::mem::manually_drop::ManuallyDrop<{async fn body@$DIR/indirect-recursion-issue-112047.rs:15:31: 17:2}>`...
-   = note: ...which requires computing layout of `{async fn body@$DIR/indirect-recursion-issue-112047.rs:15:31: 17:2}`...
+LL |         async move { recur(self).await; }
+   |                      ^^^^^^^^^^^^^^^^^
+   |
+   = note: ...which requires computing layout of `core::mem::maybe_uninit::MaybeUninit<{async fn body@$DIR/indirect-recursion-issue-112047.rs:14:31: 16:2}>`...
+   = note: ...which requires computing layout of `core::mem::manually_drop::ManuallyDrop<{async fn body@$DIR/indirect-recursion-issue-112047.rs:14:31: 16:2}>`...
+note: ...which requires computing layout of `{async fn body@$DIR/indirect-recursion-issue-112047.rs:14:31: 16:2}`...
+  --> $DIR/indirect-recursion-issue-112047.rs:15:5
+   |
+LL |     t.recur().await;
+   |     ^^^^^^^^^^^^^^^
    = note: ...which requires computing layout of `core::mem::maybe_uninit::MaybeUninit<<() as Recur>::Recur>`...
-   = note: ...which requires computing layout of `core::mem::maybe_uninit::MaybeUninit<{async block@$DIR/indirect-recursion-issue-112047.rs:23:9: 23:42}>`...
-   = note: ...which requires computing layout of `core::mem::manually_drop::ManuallyDrop<{async block@$DIR/indirect-recursion-issue-112047.rs:23:9: 23:42}>`...
-   = note: ...which again requires computing layout of `{async block@$DIR/indirect-recursion-issue-112047.rs:23:9: 23:42}`, completing the cycle
-note: cycle used when elaborating drops for `<impl at $DIR/indirect-recursion-issue-112047.rs:19:1: 19:18>::recur`
-  --> $DIR/indirect-recursion-issue-112047.rs:22:5
+   = note: ...which requires computing layout of `core::mem::maybe_uninit::MaybeUninit<{async block@$DIR/indirect-recursion-issue-112047.rs:22:9: 22:42}>`...
+   = note: ...which requires computing layout of `core::mem::manually_drop::ManuallyDrop<{async block@$DIR/indirect-recursion-issue-112047.rs:22:9: 22:42}>`...
+   = note: ...which again requires computing layout of `{async block@$DIR/indirect-recursion-issue-112047.rs:22:9: 22:42}`, completing the cycle
+note: cycle used when elaborating drops for `<impl at $DIR/indirect-recursion-issue-112047.rs:18:1: 18:18>::recur`
+  --> $DIR/indirect-recursion-issue-112047.rs:21:5
    |
 LL |     fn recur(self) -> Self::Recur {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^