Delay normalization bugs instead of reporting them

compiler/rustc_trait_selection/src/traits/misc.rs

@@ -8,8 +8,6 @@ use rustc_infer::infer::{RegionResolutionError, TyCtxtInferExt};
 use rustc_infer::{infer::outlives::env::OutlivesEnvironment, traits::FulfillmentError};
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitable};
 
-use crate::traits::error_reporting::TypeErrCtxtExt;
-
 use super::outlives_bounds::InferCtxtExt;
 
 pub enum CopyImplementationError<'tcx> {
@@ -60,8 +58,8 @@ pub fn type_allowed_to_implement_copy<'tcx>(
             let infcx = tcx.infer_ctxt().build();
             let ocx = traits::ObligationCtxt::new(&infcx);
 
-            let ty = field.ty(tcx, substs);
+            let unnormalized_ty = field.ty(tcx, substs);
-            if ty.references_error() {
+            if unnormalized_ty.references_error() {
                 continue;
             }
 
@@ -84,12 +82,10 @@ pub fn type_allowed_to_implement_copy<'tcx>(
             } else {
                 ObligationCause::dummy_with_span(field_ty_span)
             };
-            let ty = ocx.normalize(&normalization_cause, param_env, ty);
+            let ty = ocx.normalize(&normalization_cause, param_env, unnormalized_ty);
             let normalization_errors = ocx.select_where_possible();
             if !normalization_errors.is_empty() {
-                // Don't report this as a field that doesn't implement Copy,
+                tcx.sess.delay_span_bug(field_span, format!("couldn't normalize struct field `{unnormalized_ty}` when checking Copy implementation"));
-                // but instead just implement this as a field that isn't WF.
-                infcx.err_ctxt().report_fulfillment_errors(&normalization_errors, None);
                 continue;
             }
 

tests/ui/traits/copy-impl-cannot-normalize.stderr

@@ -4,6 +4,16 @@ error[E0277]: the trait bound `T: TraitFoo` is not satisfied
 LL | impl<T> Copy for Foo<T> {}
    |                  ^^^^^^ the trait `TraitFoo` is not implemented for `T`
    |
+note: required for `Foo<T>` to implement `Clone`
+  --> $DIR/copy-impl-cannot-normalize.rs:12:9
+   |
+LL | impl<T> Clone for Foo<T>
+   |         ^^^^^     ^^^^^^
+LL | where
+LL |     T: TraitFoo,
+   |        -------- unsatisfied trait bound introduced here
+note: required by a bound in `Copy`
+  --> $SRC_DIR/core/src/marker.rs:LL:COL
 help: consider restricting type parameter `T`
    |
 LL | impl<T: TraitFoo> Copy for Foo<T> {}

tests/ui/traits/issue-50480.rs

@@ -5,13 +5,11 @@ struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
 //~| ERROR cannot find type `NotDefined` in this scope
 //~| ERROR cannot find type `N` in this scope
 //~| ERROR cannot find type `N` in this scope
-//~| ERROR `i32` is not an iterator
 
 #[derive(Clone, Copy)]
 //~^ ERROR the trait `Copy` may not be implemented for this type
 struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
 //~^ ERROR cannot find type `NotDefined` in this scope
 //~| ERROR cannot find type `N` in this scope
-//~| ERROR `i32` is not an iterator
 
 fn main() {}

tests/ui/traits/issue-50480.stderr

@@ -38,7 +38,7 @@ LL | struct Foo<NotDefined>(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, St
    |           ++++++++++++
 
 error[E0412]: cannot find type `N` in this scope
-  --> $DIR/issue-50480.rs:12:18
+  --> $DIR/issue-50480.rs:11:18
    |
 LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |            -     ^
@@ -55,20 +55,11 @@ LL | struct Bar<T, N>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, Strin
    |             +++
 
 error[E0412]: cannot find type `NotDefined` in this scope
-  --> $DIR/issue-50480.rs:12:21
+  --> $DIR/issue-50480.rs:11:21
    |
 LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |                     ^^^^^^^^^^ not found in this scope
 
-error[E0277]: `i32` is not an iterator
-  --> $DIR/issue-50480.rs:3:27
-   |
-LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
-   |                           ^^^^^^^^^^^^^^^^^^^^^^^ `i32` is not an iterator
-   |
-   = help: the trait `Iterator` is not implemented for `i32`
-   = note: if you want to iterate between `start` until a value `end`, use the exclusive range syntax `start..end` or the inclusive range syntax `start..=end`
-
 error[E0204]: the trait `Copy` may not be implemented for this type
   --> $DIR/issue-50480.rs:1:17
    |
@@ -82,17 +73,8 @@ LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0277]: `i32` is not an iterator
-  --> $DIR/issue-50480.rs:12:33
-   |
-LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^ `i32` is not an iterator
-   |
-   = help: the trait `Iterator` is not implemented for `i32`
-   = note: if you want to iterate between `start` until a value `end`, use the exclusive range syntax `start..end` or the inclusive range syntax `start..=end`
-
 error[E0204]: the trait `Copy` may not be implemented for this type
-  --> $DIR/issue-50480.rs:10:17
+  --> $DIR/issue-50480.rs:9:17
    |
 LL | #[derive(Clone, Copy)]
    |                 ^^^^
@@ -104,7 +86,7 @@ LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 10 previous errors
+error: aborting due to 8 previous errors
 
-Some errors have detailed explanations: E0204, E0277, E0412.
+Some errors have detailed explanations: E0204, E0412.
 For more information about an error, try `rustc --explain E0204`.