Auto merge of #115392 - compiler-errors:coherence-spans, r=aliemjay

Don't record spans for predicates in coherence

Should improve perf (#115107 (comment)) for #114023 (comment)

r? aliemjay

Author: bors

compiler/rustc_middle/src/ty/mod.rs

@@ -238,7 +238,7 @@ pub struct ImplHeader<'tcx> {
     pub impl_def_id: DefId,
     pub self_ty: Ty<'tcx>,
     pub trait_ref: Option<TraitRef<'tcx>>,
-    pub predicates: Vec<(Predicate<'tcx>, Span)>,
+    pub predicates: Vec<Predicate<'tcx>>,
 }
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable)]

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -152,16 +152,14 @@ fn with_fresh_ty_vars<'cx, 'tcx>(
             .predicates_of(impl_def_id)
             .instantiate(tcx, impl_args)
             .iter()
-            .map(|(c, s)| (c.as_predicate(), s))
+            .map(|(c, _)| c.as_predicate())
             .collect(),
     };
 
-    let InferOk { value: mut header, obligations } = selcx
-        .infcx
-        .at(&ObligationCause::dummy_with_span(tcx.def_span(impl_def_id)), param_env)
-        .normalize(header);
+    let InferOk { value: mut header, obligations } =
+        selcx.infcx.at(&ObligationCause::dummy(), param_env).normalize(header);
 
-    header.predicates.extend(obligations.into_iter().map(|o| (o.predicate, o.cause.span)));
+    header.predicates.extend(obligations.into_iter().map(|o| o.predicate));
     header
 }
 
@@ -261,17 +259,11 @@ fn overlap<'tcx>(
                                 infcx.tcx.def_span(impl2_header.impl_def_id),
                                 "the second impl is here",
                             );
-                            if !failing_obligation.cause.span.is_dummy() {
-                                lint.span_label(
-                                    failing_obligation.cause.span,
-                                    format!(
-                                        "`{}` may be considered to hold in future releases, \
-                                        causing the impls to overlap",
-                                        infcx
-                                            .resolve_vars_if_possible(failing_obligation.predicate)
-                                    ),
-                                );
-                            }
+                            lint.note(format!(
+                                "`{}` may be considered to hold in future releases, \
+                                    causing the impls to overlap",
+                                infcx.resolve_vars_if_possible(failing_obligation.predicate)
+                            ));
                             lint
                         },
                     );
@@ -355,8 +347,8 @@ fn impl_intersection_has_impossible_obligation<'cx, 'tcx>(
     [&impl1_header.predicates, &impl2_header.predicates]
         .into_iter()
         .flatten()
-        .map(|&(predicate, span)| {
-            Obligation::new(infcx.tcx, ObligationCause::dummy_with_span(span), param_env, predicate)
+        .map(|&predicate| {
+            Obligation::new(infcx.tcx, ObligationCause::dummy(), param_env, predicate)
         })
         .chain(obligations.into_iter().cloned())
         .find(|obligation: &PredicateObligation<'tcx>| {

tests/ui/coherence/warn-when-cycle-is-error-in-coherence.stderr

@@ -6,13 +6,11 @@ LL | #[derive(PartialEq, Default)]
 ...
 LL | impl<T, Q> PartialEq<Q> for Interval<T>
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the first impl is here
-...
-LL |     Q: ?Sized + PartialOrd,
-   |                 ---------- `Interval<_>: PartialOrd` may be considered to hold in future releases, causing the impls to overlap
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #114040 <https://github.com/rust-lang/rust/issues/114040>
    = note: impls that are not considered to overlap may be considered to overlap in the future
+   = note: `Interval<_>: PartialOrd` may be considered to hold in future releases, causing the impls to overlap
 note: the lint level is defined here
   --> $DIR/warn-when-cycle-is-error-in-coherence.rs:1:9
    |

tests/ui/traits/issue-105231.rs

@@ -1,9 +1,9 @@
+//~ ERROR overflow evaluating the requirement `A<A<A<A<A<A<A<...>>>>>>>: Send`
 struct A<T>(B<T>);
 //~^ ERROR recursive types `A` and `B` have infinite size
 struct B<T>(A<A<T>>);
 trait Foo {}
 impl<T> Foo for T where T: Send {}
-//~^ ERROR overflow evaluating the requirement `A<A<A<A<A<A<A<...>>>>>>>: Send`
 impl Foo for B<u8> {}
 
 fn main() {}

tests/ui/traits/issue-105231.stderr

@@ -1,5 +1,5 @@
 error[E0072]: recursive types `A` and `B` have infinite size
-  --> $DIR/issue-105231.rs:1:1
+  --> $DIR/issue-105231.rs:2:1
    |
 LL | struct A<T>(B<T>);
    | ^^^^^^^^^^^ ---- recursive without indirection
@@ -15,14 +15,10 @@ LL ~ struct B<T>(Box<A<A<T>>>);
    |
 
 error[E0275]: overflow evaluating the requirement `A<A<A<A<A<A<A<...>>>>>>>: Send`
-  --> $DIR/issue-105231.rs:5:28
-   |
-LL | impl<T> Foo for T where T: Send {}
-   |                            ^^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_105231`)
 note: required because it appears within the type `B<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<u8>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
-  --> $DIR/issue-105231.rs:3:8
+  --> $DIR/issue-105231.rs:4:8
    |
 LL | struct B<T>(A<A<T>>);
    |        ^

tests/ui/traits/solver-cycles/cycle-via-builtin-auto-trait-impl.rs

@@ -1,3 +1,4 @@
+//~ ERROR overflow
 // A regression test for #111729 checking that we correctly
 // track recursion depth for obligations returned by confirmation.
 use std::panic::RefUnwindSafe;
@@ -14,7 +15,6 @@ struct RootDatabase {
 }
 
 impl<T: RefUnwindSafe> Database for T {
-    //~^ ERROR overflow
     type Storage = SalsaStorage;
 }
 impl Database for RootDatabase {

tests/ui/traits/solver-cycles/cycle-via-builtin-auto-trait-impl.stderr

@@ -1,17 +1,13 @@
 error[E0275]: overflow evaluating the requirement `Runtime<RootDatabase>: RefUnwindSafe`
-  --> $DIR/cycle-via-builtin-auto-trait-impl.rs:16:9
-   |
-LL | impl<T: RefUnwindSafe> Database for T {
-   |         ^^^^^^^^^^^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`cycle_via_builtin_auto_trait_impl`)
 note: required because it appears within the type `RootDatabase`
-  --> $DIR/cycle-via-builtin-auto-trait-impl.rs:12:8
+  --> $DIR/cycle-via-builtin-auto-trait-impl.rs:13:8
    |
 LL | struct RootDatabase {
    |        ^^^^^^^^^^^^
 note: required for `RootDatabase` to implement `Database`
-  --> $DIR/cycle-via-builtin-auto-trait-impl.rs:16:24
+  --> $DIR/cycle-via-builtin-auto-trait-impl.rs:17:24
    |
 LL | impl<T: RefUnwindSafe> Database for T {
    |         -------------  ^^^^^^^^     ^