explicitly handle errors in fulfill

2 files changed, 26 insertions, 25 deletions

diff --git a/src/librustc_trait_selection/traits/fulfill.rs b/src/librustc_trait_selection/traits/fulfill.rs
index cf107a6c5b5..98f6ac0e547 100644
--- a/src/librustc_trait_selection/traits/fulfill.rs
+++ b/src/librustc_trait_selection/traits/fulfill.rs
@@ -2,6 +2,7 @@ use crate::infer::{InferCtxt, TyOrConstInferVar};
 use rustc_data_structures::obligation_forest::ProcessResult;
 use rustc_data_structures::obligation_forest::{DoCompleted, Error, ForestObligation};
 use rustc_data_structures::obligation_forest::{ObligationForest, ObligationProcessor};
+use rustc_errors::ErrorReported;
 use rustc_infer::traits::{TraitEngine, TraitEngineExt as _};
 use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::ty::error::ExpectedFound;
@@ -544,11 +545,9 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
                                         .filter_map(|ty| TyOrConstInferVar::maybe_from_ty(ty))
                                         .collect(),
                                 );
-                                Err(ProcessResult::Unchanged)
-                            }
-                            Err(err) => {
-                                Err(ProcessResult::Error(CodeSelectionError(ConstEvalFailure(err))))
+                                Err(ErrorHandled::TooGeneric)
                             }
+                            Err(err) => Err(err),
                         }
                     } else {
                         Ok(c)
@@ -572,15 +571,17 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
                             }
                         }
                     }
-                    // FIXME(skinny121) How to report both errors if both produces errors?
-                    (Err(result @ ProcessResult::Error(_)), _)
-                    | (_, Err(result @ ProcessResult::Error(_))) => result,
-                    (Err(ProcessResult::Unchanged), _) | (_, Err(ProcessResult::Unchanged)) => {
+                    (Err(ErrorHandled::Reported(ErrorReported)), _)
+                    | (_, Err(ErrorHandled::Reported(ErrorReported))) => ProcessResult::Error(
+                        CodeSelectionError(ConstEvalFailure(ErrorHandled::Reported(ErrorReported))),
+                    ),
+                    (Err(ErrorHandled::Linted), _) | (_, Err(ErrorHandled::Linted)) => span_bug!(
+                        obligation.cause.span(self.selcx.tcx()),
+                        "ConstEquate: const_eval_resolve returned an unexpected error"
+                    ),
+                    (Err(ErrorHandled::TooGeneric), _) | (_, Err(ErrorHandled::TooGeneric)) => {
                         ProcessResult::Unchanged
                     }
-                    _ => {
-                        unreachable!("evaluate shouldn't itself return ProcessResult::Changed(..)")
-                    }
                 }
             }
         }
diff --git a/src/test/ui/const-generics/lazy-normalization/lazy-normalization-feature-gate.stderr b/src/test/ui/const-generics/lazy-normalization/lazy-normalization-feature-gate.stderr
index 8a97ec0c5fc..9a7844f5e8f 100644
--- a/src/test/ui/const-generics/lazy-normalization/lazy-normalization-feature-gate.stderr
+++ b/src/test/ui/const-generics/lazy-normalization/lazy-normalization-feature-gate.stderr
@@ -1,40 +1,40 @@
 warning: the feature `const_generics` is incomplete and may cause the compiler to crash
-  --> $DIR/lazy-normalization-feature-gate-hack.rs:2:12
+  --> $DIR/lazy-normalization-feature-gate.rs:2:12
    |
 LL | #![feature(const_generics)]
    |            ^^^^^^^^^^^^^^
    |
    = note: `#[warn(incomplete_features)]` on by default
 
-error[E0391]: cycle detected when const-evaluating + checking `<impl at $DIR/lazy-normalization-feature-gate-hack.rs:6:1: 6:72>::{{constant}}#0`
-  --> $DIR/lazy-normalization-feature-gate-hack.rs:6:58
+error[E0391]: cycle detected when const-evaluating + checking `<impl at $DIR/lazy-normalization-feature-gate.rs:6:1: 6:72>::{{constant}}#0`
+  --> $DIR/lazy-normalization-feature-gate.rs:6:58
    |
 LL | impl<const N: usize> Foo for [(); N] where Self: FooImpl<{ N == 0 }> {}
    |                                                          ^^^^^^^^^^
    |
-note: ...which requires const-evaluating + checking `<impl at $DIR/lazy-normalization-feature-gate-hack.rs:6:1: 6:72>::{{constant}}#0`...
-  --> $DIR/lazy-normalization-feature-gate-hack.rs:6:58
+note: ...which requires const-evaluating + checking `<impl at $DIR/lazy-normalization-feature-gate.rs:6:1: 6:72>::{{constant}}#0`...
+  --> $DIR/lazy-normalization-feature-gate.rs:6:58
    |
 LL | impl<const N: usize> Foo for [(); N] where Self: FooImpl<{ N == 0 }> {}
    |                                                          ^^^^^^^^^^
-note: ...which requires const-evaluating `<impl at $DIR/lazy-normalization-feature-gate-hack.rs:6:1: 6:72>::{{constant}}#0`...
-  --> $DIR/lazy-normalization-feature-gate-hack.rs:6:58
+note: ...which requires const-evaluating `<impl at $DIR/lazy-normalization-feature-gate.rs:6:1: 6:72>::{{constant}}#0`...
+  --> $DIR/lazy-normalization-feature-gate.rs:6:58
    |
 LL | impl<const N: usize> Foo for [(); N] where Self: FooImpl<{ N == 0 }> {}
    |                                                          ^^^^^^^^^^
-note: ...which requires type-checking `<impl at $DIR/lazy-normalization-feature-gate-hack.rs:6:1: 6:72>::{{constant}}#0`...
-  --> $DIR/lazy-normalization-feature-gate-hack.rs:6:58
+note: ...which requires type-checking `<impl at $DIR/lazy-normalization-feature-gate.rs:6:1: 6:72>::{{constant}}#0`...
+  --> $DIR/lazy-normalization-feature-gate.rs:6:58
    |
 LL | impl<const N: usize> Foo for [(); N] where Self: FooImpl<{ N == 0 }> {}
    |                                                          ^^^^^^^^^^
-note: ...which requires processing `<impl at $DIR/lazy-normalization-feature-gate-hack.rs:6:1: 6:72>::{{constant}}#0`...
-  --> $DIR/lazy-normalization-feature-gate-hack.rs:6:58
+note: ...which requires processing `<impl at $DIR/lazy-normalization-feature-gate.rs:6:1: 6:72>::{{constant}}#0`...
+  --> $DIR/lazy-normalization-feature-gate.rs:6:58
    |
 LL | impl<const N: usize> Foo for [(); N] where Self: FooImpl<{ N == 0 }> {}
    |                                                          ^^^^^^^^^^
-   = note: ...which again requires const-evaluating + checking `<impl at $DIR/lazy-normalization-feature-gate-hack.rs:6:1: 6:72>::{{constant}}#0`, completing the cycle
-note: cycle used when processing `<impl at $DIR/lazy-normalization-feature-gate-hack.rs:6:1: 6:72>`
-  --> $DIR/lazy-normalization-feature-gate-hack.rs:6:1
+   = note: ...which again requires const-evaluating + checking `<impl at $DIR/lazy-normalization-feature-gate.rs:6:1: 6:72>::{{constant}}#0`, completing the cycle
+note: cycle used when processing `<impl at $DIR/lazy-normalization-feature-gate.rs:6:1: 6:72>`
+  --> $DIR/lazy-normalization-feature-gate.rs:6:1
    |
 LL | impl<const N: usize> Foo for [(); N] where Self: FooImpl<{ N == 0 }> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^