Revert "Fix regression: the feature is not needed"

This reverts commit 675ad69.

Author: tiif

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -819,9 +819,7 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &ty::GenericParamDef) -> Result<(), Er
             let span = tcx.def_span(param.def_id);
             let def_id = param.def_id.expect_local();
 
-            if tcx.features().adt_const_params()
-                || tcx.features().enabled(sym::unsized_const_params)
-            {
+            if tcx.features().adt_const_params() {
                 enter_wf_checking_ctxt(tcx, tcx.local_parent(def_id), |wfcx| {
                     wfcx.register_bound(
                         ObligationCause::new(span, def_id, ObligationCauseCode::ConstParam(ty)),

tests/ui/const-generics/adt_const_params/non_valtreeable_const_arg-2.stderr

@@ -9,11 +9,13 @@ help: you might be missing a const parameter
 LL | impl<const bar: /* Type */> Wrapper<{ bar() }> {
    |     +++++++++++++++++++++++
 
-error[E0741]: using function pointers as const generic parameters is forbidden
+error: using function pointers as const generic parameters is forbidden
   --> $DIR/non_valtreeable_const_arg-2.rs:8:25
    |
 LL | struct Wrapper<const F: fn()>;
    |                         ^^^^
+   |
+   = note: the only supported types are integers, `bool`, and `char`
 
 error[E0599]: the function or associated item `call` exists for struct `Wrapper<function>`, but its trait bounds were not satisfied
   --> $DIR/non_valtreeable_const_arg-2.rs:17:26
@@ -35,5 +37,5 @@ note: the trait `Fn` must be implemented
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0425, E0599, E0741.
+Some errors have detailed explanations: E0425, E0599.
 For more information about an error, try `rustc --explain E0425`.

tests/ui/const-generics/unsized_const_params/symbol_mangling_v0_str.rs

@@ -1,7 +1,7 @@
 //@ check-pass
 //@ compile-flags: -Csymbol-mangling-version=v0
 #![allow(incomplete_features)]
-#![feature(unsized_const_params)]
+#![feature(adt_const_params, unsized_const_params)]
 
 // Regression test for #116303