Rollup merge of #133371 - RalfJung:is_trivially_const_drop, r=compiler-errors

remove is_trivially_const_drop

I'm not sure this still brings any perf benefits, so let's benchmark this.

r? `@compiler-errors`

compiler/rustc_const_eval/src/check_consts/qualifs.rs

@@ -170,11 +170,6 @@ impl Qualif for NeedsNonConstDrop {
 
     #[instrument(level = "trace", skip(cx), ret)]
     fn in_any_value_of_ty<'tcx>(cx: &ConstCx<'_, 'tcx>, ty: Ty<'tcx>) -> bool {
-        // Avoid selecting for simple cases, such as builtin types.
-        if ty::util::is_trivially_const_drop(ty) {
-            return false;
-        }
-
         // If this doesn't need drop at all, then don't select `~const Destruct`.
         if !ty.needs_drop(cx.tcx, cx.typing_env) {
             return false;

compiler/rustc_middle/src/ty/util.rs

@@ -1672,45 +1672,6 @@ pub fn needs_drop_components_with_async<'tcx>(
     }
 }
 
-pub fn is_trivially_const_drop(ty: Ty<'_>) -> bool {
-    match *ty.kind() {
-        ty::Bool
-        | ty::Char
-        | ty::Int(_)
-        | ty::Uint(_)
-        | ty::Float(_)
-        | ty::Infer(ty::IntVar(_))
-        | ty::Infer(ty::FloatVar(_))
-        | ty::Str
-        | ty::RawPtr(_, _)
-        | ty::Ref(..)
-        | ty::FnDef(..)
-        | ty::FnPtr(..)
-        | ty::Never
-        | ty::Foreign(_) => true,
-
-        ty::Alias(..)
-        | ty::Dynamic(..)
-        | ty::Error(_)
-        | ty::Bound(..)
-        | ty::Param(_)
-        | ty::Placeholder(_)
-        | ty::Infer(_) => false,
-
-        // Not trivial because they have components, and instead of looking inside,
-        // we'll just perform trait selection.
-        ty::Closure(..)
-        | ty::CoroutineClosure(..)
-        | ty::Coroutine(..)
-        | ty::CoroutineWitness(..)
-        | ty::Adt(..) => false,
-
-        ty::Array(ty, _) | ty::Slice(ty) | ty::Pat(ty, _) => is_trivially_const_drop(ty),
-
-        ty::Tuple(tys) => tys.iter().all(|ty| is_trivially_const_drop(ty)),
-    }
-}
-
 /// Does the equivalent of
 /// ```ignore (illustrative)
 /// let v = self.iter().map(|p| p.fold_with(folder)).collect::<SmallVec<[_; 8]>>();

src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs

@@ -404,12 +404,11 @@ fn is_ty_const_destruct<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, body: &Body<'tcx>
     // 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.
-        if ty::util::is_trivially_const_drop(ty) {
-            return true;
+        // If this doesn't need drop at all, then don't select `~const Destruct`.
+        if !ty.needs_drop(tcx, body.typing_env(tcx)) {
+            return false;
         }
 
-
         let (infcx, param_env) =
             tcx.infer_ctxt().build_with_typing_env(body.typing_env(tcx));
         // FIXME(const_trait_impl) constness