Auto merge of #114134 - fee1-dead-contrib:rm-constness-from-param-env, r=oli-obk

Remove `constness` from `ParamEnv`

This should be replaced by keyword generics/effects. cc #110395

r? `@oli-obk`

Author: bors

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -409,18 +409,12 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
             }
 
             if let ty::FnDef(def_id, args) = *constant.literal.ty().kind() {
-                // const_trait_impl: use a non-const param env when checking that a FnDef type is well formed.
-                // this is because the well-formedness of the function does not need to be proved to have `const`
-                // impls for trait bounds.
                 let instantiated_predicates = tcx.predicates_of(def_id).instantiate(tcx, args);
-                let prev = self.cx.param_env;
-                self.cx.param_env = prev.without_const();
                 self.cx.normalize_and_prove_instantiated_predicates(
                     def_id,
                     instantiated_predicates,
                     locations,
                 );
-                self.cx.param_env = prev;
             }
         }
     }

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

@@ -228,7 +228,6 @@ pub fn eval_to_const_value_raw_provider<'tcx>(
     tcx: TyCtxt<'tcx>,
     key: ty::ParamEnvAnd<'tcx, GlobalId<'tcx>>,
 ) -> ::rustc_middle::mir::interpret::EvalToConstValueResult<'tcx> {
-    assert!(key.param_env.is_const());
     // see comment in eval_to_allocation_raw_provider for what we're doing here
     if key.param_env.reveal() == Reveal::All {
         let mut key = key;
@@ -269,7 +268,6 @@ pub fn eval_to_allocation_raw_provider<'tcx>(
     tcx: TyCtxt<'tcx>,
     key: ty::ParamEnvAnd<'tcx, GlobalId<'tcx>>,
 ) -> ::rustc_middle::mir::interpret::EvalToAllocationRawResult<'tcx> {
-    assert!(key.param_env.is_const());
     // Because the constant is computed twice (once per value of `Reveal`), we are at risk of
     // reporting the same error twice here. To resolve this, we check whether we can evaluate the
     // constant in the more restrictive `Reveal::UserFacing`, which most likely already was