Rollup merge of #97722 - compiler-errors:tighten-copy-type-error-spans, r=Dylan-DPC

Tighten spans for bad fields in struct deriving `Copy`

r? `@estebank`

Closes #89137 for good, I think

Not sure if this is what you were looking for in #89137 (comment)

Author: Dylan-DPC

compiler/rustc_trait_selection/src/traits/misc.rs

@@ -20,7 +20,7 @@ pub fn can_type_implement_copy<'tcx>(
     tcx: TyCtxt<'tcx>,
     param_env: ty::ParamEnv<'tcx>,
     self_type: Ty<'tcx>,
-    cause: ObligationCause<'tcx>,
+    parent_cause: ObligationCause<'tcx>,
 ) -> Result<(), CopyImplementationError<'tcx>> {
     // FIXME: (@jroesch) float this code up
     tcx.infer_ctxt().enter(|infcx| {
@@ -59,7 +59,7 @@ pub fn can_type_implement_copy<'tcx>(
                     .ty(tcx, traits::InternalSubsts::identity_for_item(tcx, adt.did()))
                     .has_param_types_or_consts()
                 {
-                    cause.clone()
+                    parent_cause.clone()
                 } else {
                     ObligationCause::dummy_with_span(span)
                 };

compiler/rustc_typeck/src/coherence/builtin.rs

@@ -107,6 +107,10 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
 
             for (field, ty) in fields {
                 let field_span = tcx.def_span(field.did);
+                let field_ty_span = match tcx.hir().get_if_local(field.did) {
+                    Some(hir::Node::Field(field_def)) => field_def.ty.span,
+                    _ => field_span,
+                };
                 err.span_label(field_span, "this field does not implement `Copy`");
                 // Spin up a new FulfillmentContext, so we can get the _precise_ reason
                 // why this field does not implement Copy. This is useful because sometimes
@@ -119,7 +123,7 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
                         param_env,
                         ty,
                         tcx.lang_items().copy_trait().unwrap(),
-                        traits::ObligationCause::dummy_with_span(field_span),
+                        traits::ObligationCause::dummy_with_span(field_ty_span),
                     );
                     for error in fulfill_cx.select_all_or_error(&infcx) {
                         let error_predicate = error.obligation.predicate;

src/test/ui/suggestions/missing-bound-in-derive-copy-impl-3.stderr

@@ -10,12 +10,12 @@ LL |     pub size: Vector2<K>
    |     -------------------- this field does not implement `Copy`
    |
 note: the `Copy` impl for `Vector2<K>` requires that `K: Debug`
-  --> $DIR/missing-bound-in-derive-copy-impl-3.rs:12:5
+  --> $DIR/missing-bound-in-derive-copy-impl-3.rs:12:14
    |
 LL |     pub loc: Vector2<K>,
-   |     ^^^^^^^^^^^^^^^^^^^
+   |              ^^^^^^^^^^
 LL |     pub size: Vector2<K>
-   |     ^^^^^^^^^^^^^^^^^^^^
+   |               ^^^^^^^^^^
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
 help: consider further restricting this bound
    |

src/test/ui/suggestions/missing-bound-in-derive-copy-impl.stderr

@@ -10,12 +10,12 @@ LL |     pub size: Vector2<K>
    |     -------------------- this field does not implement `Copy`
    |
 note: the `Copy` impl for `Vector2<K>` requires that `K: Debug`
-  --> $DIR/missing-bound-in-derive-copy-impl.rs:11:5
+  --> $DIR/missing-bound-in-derive-copy-impl.rs:11:14
    |
 LL |     pub loc: Vector2<K>,
-   |     ^^^^^^^^^^^^^^^^^^^
+   |              ^^^^^^^^^^
 LL |     pub size: Vector2<K>
-   |     ^^^^^^^^^^^^^^^^^^^^
+   |               ^^^^^^^^^^
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
 help: consider restricting type parameter `K`
    |

src/test/ui/union/union-copy.stderr

@@ -8,10 +8,10 @@ LL | impl Copy for W {}
    |      ^^^^
    |
 note: the `Copy` impl for `ManuallyDrop<String>` requires that `String: Copy`
-  --> $DIR/union-copy.rs:8:5
+  --> $DIR/union-copy.rs:8:8
    |
 LL |     a: std::mem::ManuallyDrop<String>
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error