Allow type op to delay ambiguity

Author: compiler-errors

compiler/rustc_middle/src/traits/query.rs

@@ -116,12 +116,24 @@ pub enum NoSolutionOrAmbiguous {
 }
 
 impl NoSolutionOrAmbiguous {
+    // Expect unambiguous errors only
     pub fn expect_unambiguous(self) -> NoSolution {
         match self {
             NoSolutionOrAmbiguous::NoSolution => NoSolution,
             NoSolutionOrAmbiguous::Ambiguous => bug!("unexpected ambiguity"),
         }
     }
+
+    /// Delay an ambiguity as a `delay_span_bug`.
+    pub fn delay_ambiguous(self, tcx: TyCtxt<'_>, span: Span) -> NoSolution {
+        match self {
+            NoSolutionOrAmbiguous::NoSolution => NoSolution,
+            NoSolutionOrAmbiguous::Ambiguous => {
+                tcx.sess.delay_span_bug(span, "unexpected ambiguity");
+                NoSolution
+            }
+        }
+    }
 }
 
 impl From<NoSolution> for NoSolutionOrAmbiguous {

compiler/rustc_traits/src/type_op.rs

@@ -221,7 +221,7 @@ where
     let Normalized { value, obligations } = infcx
         .at(&ObligationCause::dummy(), param_env)
         .normalize(value)
-        .map_err(|err| err.expect_unambiguous())?;
+        .map_err(|err| err.delay_ambiguous(infcx.tcx, DUMMY_SP))?;
     fulfill_cx.register_predicate_obligations(infcx, obligations);
     Ok(value)
 }