Add is_intrinsic helper

Author: oli-obk

compiler/rustc_hir_typeck/src/callee.rs

@@ -545,7 +545,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         if let Some(def_id) = def_id
             && self.tcx.def_kind(def_id) == hir::def::DefKind::Fn
-            && matches!(self.tcx.intrinsic(def_id), Some(sym::const_eval_select))
+            && self.tcx.is_intrinsic(def_id, sym::const_eval_select)
         {
             let fn_sig = self.resolve_vars_if_possible(fn_sig);
             for idx in 0..=1 {

compiler/rustc_lint/src/builtin.rs

@@ -1231,7 +1231,7 @@ impl<'tcx> LateLintPass<'tcx> for MutableTransmutes {
         }
 
         fn def_id_is_transmute(cx: &LateContext<'_>, def_id: DefId) -> bool {
-            matches!(cx.tcx.intrinsic(def_id), Some(sym::transmute))
+            cx.tcx.is_intrinsic(def_id, sym::transmute)
         }
     }
 }

compiler/rustc_middle/src/ty/intrinsic.rs

@@ -0,0 +1,10 @@
+use rustc_span::{def_id::DefId, Symbol};
+
+use super::TyCtxt;
+
+impl TyCtxt<'_> {
+    pub fn is_intrinsic(self, def_id: DefId, name: Symbol) -> bool {
+        let Some(i) = self.intrinsic(def_id) else { return false };
+        i == name
+    }
+}

compiler/rustc_middle/src/ty/mod.rs

@@ -149,6 +149,7 @@ mod generic_args;
 mod generics;
 mod impls_ty;
 mod instance;
+mod intrinsic;
 mod list;
 mod opaque_types;
 mod parameterized;

compiler/rustc_mir_transform/src/lib.rs

@@ -160,7 +160,7 @@ fn remap_mir_for_const_eval_select<'tcx>(
                 fn_span,
                 ..
             } if let ty::FnDef(def_id, _) = *const_.ty().kind()
-                && matches!(tcx.intrinsic(def_id), Some(sym::const_eval_select)) =>
+                && tcx.is_intrinsic(def_id, sym::const_eval_select) =>
             {
                 let [tupled_args, called_in_const, called_at_rt]: [_; 3] =
                     std::mem::take(args).try_into().unwrap();

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

@@ -334,7 +334,7 @@ fn check_terminator<'tcx>(
                 // within const fns. `transmute` is allowed in all other const contexts.
                 // This won't really scale to more intrinsics or functions. Let's allow const
                 // transmutes in const fn before we add more hacks to this.
-                if matches!(tcx.intrinsic(fn_def_id), Some(sym::transmute)) {
+                if tcx.is_intrinsic(fn_def_id, sym::transmute) {
                     return Err((
                         span,
                         "can only call `transmute` from const items, not `const fn`".into(),