Rollup merge of #119725 - compiler-errors:has_effect_param, r=fmease

Add helper for when we want to know if an item has a host param

r? ````@fmease```` since you're a good reviewer and no good deed goes unpunished

This helper will see far more usages as built-in traits get constified.

1 files changed, 8 insertions, 1 deletions

diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index b9c75bd205b..f2a33429bd7 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -1,7 +1,7 @@
 //! Miscellaneous type-system utilities that are too small to deserve their own modules.
 
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
-use crate::query::Providers;
+use crate::query::{IntoQueryParam, Providers};
 use crate::ty::layout::IntegerExt;
 use crate::ty::{
     self, FallibleTypeFolder, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable,
@@ -786,6 +786,13 @@ impl<'tcx> TyCtxt<'tcx> {
             || self.extern_crate(key.as_def_id()).is_some_and(|e| e.is_direct())
     }
 
+    /// Whether the item has a host effect param. This is different from `TyCtxt::is_const`,
+    /// because the item must also be "maybe const", and the crate where the item is
+    /// defined must also have the effects feature enabled.
+    pub fn has_host_param(self, def_id: impl IntoQueryParam<DefId>) -> bool {
+        self.generics_of(def_id).host_effect_index.is_some()
+    }
+
     pub fn expected_host_effect_param_for_body(self, def_id: impl Into<DefId>) -> ty::Const<'tcx> {
         let def_id = def_id.into();
         // FIXME(effects): This is suspicious and should probably not be done,