Auto merge of #132479 - compiler-errors:fx-feat-yeet, r=fee1-dead

Yeet the `effects` feature, move it onto `const_trait_impl`

This PR merges the `effects` feature into the `const_trait_impl` feature. There's really no need to have two feature gates for one feature.

After this PR, if `const_trait_impl` **is** enabled:
* Users can use and define const traits
* `HostEffect` const conditions will be enforced on the HIR
* We re-check the predicates in MIR just to make sure that we don't "leak" anything during MIR lowering

And if `const_trait_impl` **is not** enabled:
* Users cannot use nor define const traits
* `HostEffect` const conditions are not enforced on the HIR
* We will raise a const validation error if we call a function that has any const conditions (i.e. const traits and functions with any `~const` in their where clasues)

This should be the last step for us to be able to enable const traits in the standard library. We still need to re-constify `Drop` and `Destruct` and stuff for const traits to be particularly *useful* for some cases, but this is a good step :D

r? fee1-dead
cc `@rust-lang/project-const-traits`

3 files changed, 6 insertions, 6 deletions

diff --git a/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs b/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
index 8f9f75d6824..666ec8df930 100644
--- a/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
+++ b/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
@@ -404,7 +404,7 @@ fn is_stable_const_fn(tcx: TyCtxt<'_>, def_id: DefId, msrv: &Msrv) -> bool {
 }
 
 fn is_ty_const_destruct<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, body: &Body<'tcx>) -> bool {
-    // FIXME(effects, fee1-dead) revert to const destruct once it works again
+    // FIXME(const_trait_impl, fee1-dead) revert to const destruct once it works again
     #[expect(unused)]
     fn is_ty_const_destruct_unused<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, body: &Body<'tcx>) -> bool {
         // Avoid selecting for simple cases, such as builtin types.
@@ -412,7 +412,7 @@ fn is_ty_const_destruct<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, body: &Body<'tcx>
             return true;
         }
 
-        // FIXME(effects) constness
+        // FIXME(const_trait_impl) constness
         let obligation = Obligation::new(
             tcx,
             ObligationCause::dummy_with_span(body.span),
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.fixed b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.fixed
index f7b6e1a186b..7c882789511 100644
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.fixed
+++ b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.fixed
@@ -104,7 +104,7 @@ fn main() {}
 
 struct D;
 
-/* FIXME(effects)
+/* FIXME(const_trait_impl)
 impl const Drop for D {
     fn drop(&mut self) {
         todo!();
@@ -113,7 +113,7 @@ impl const Drop for D {
 */
 
 // Lint this, since it can be dropped in const contexts
-// FIXME(effects)
+// FIXME(const_trait_impl)
 const fn d(this: D) {}
 //~^ ERROR: this could be a `const fn`
 
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.rs b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.rs
index 4866e321024..48312d48ed3 100644
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.rs
+++ b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.rs
@@ -104,7 +104,7 @@ fn main() {}
 
 struct D;
 
-/* FIXME(effects)
+/* FIXME(const_trait_impl)
 impl const Drop for D {
     fn drop(&mut self) {
         todo!();
@@ -113,7 +113,7 @@ impl const Drop for D {
 */
 
 // Lint this, since it can be dropped in const contexts
-// FIXME(effects)
+// FIXME(const_trait_impl)
 fn d(this: D) {}
 //~^ ERROR: this could be a `const fn`