Fix duplicate bounds for const_trait_impl

diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 22013fb79cf797d3f68dd9d49a02331ee5e8b331..3c83938ce43ee6b160bfae58e6fcd079851c1282 100644 (file)
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -1487,10 +1487,11 @@ fn candidate_should_be_dropped_in_favor_of(
             ) => false,
 
             (ParamCandidate(other), ParamCandidate(victim)) => {
-                let value_same_except_bound_vars = other.value.skip_binder()
+                let same_except_bound_vars = other.value.skip_binder()
                     == victim.value.skip_binder()
+                    && other.constness == victim.constness
                     && !other.value.skip_binder().has_escaping_bound_vars();
-                if value_same_except_bound_vars {
+                if same_except_bound_vars {
                     // See issue #84398. In short, we can generate multiple ParamCandidates which are
                     // the same except for unused bound vars. Just pick the one with the fewest bound vars
                     // or the current one if tied (they should both evaluate to the same answer). This is

diff --git a/src/test/ui/rfc-2632-const-trait-impl/call-generic-method-dup-bound.rs b/src/test/ui/rfc-2632-const-trait-impl/call-generic-method-dup-bound.rs
index 7185376b440c8fdf10e7b029f7f94f2a4ac1acba..cc24dbd96d2532ebc82c59a2e9fc4a7514891d86 100644 (file)
--- a/src/test/ui/rfc-2632-const-trait-impl/call-generic-method-dup-bound.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/call-generic-method-dup-bound.rs
@@ -16,12 +16,17 @@ fn ne(&self, other: &S) -> bool {
 
 // This duplicate bound should not result in ambiguities. It should be equivalent to a single ~const
 // bound.
-// const fn equals_self<T: PartialEq + ~const PartialEq>(t: &T) -> bool {
-// FIXME(fee1-dead)^ why should the order matter here?
-const fn equals_self<T: ~const PartialEq + PartialEq>(t: &T) -> bool {
+const fn equals_self<T: PartialEq + ~const PartialEq>(t: &T) -> bool {
     *t == *t
 }
 
-pub const EQ: bool = equals_self(&S);
+trait A: PartialEq {}
+impl<T: PartialEq> A for T {}
+
+const fn equals_self2<T: A + ~const PartialEq>(t: &T) -> bool {
+    *t == *t
+}
+
+pub const EQ: bool = equals_self(&S) && equals_self2(&S);
 
 fn main() {}