fix ensure_monomorphic_enough

(cherry picked from commit c1da4f1)

Author: Lukas Markeffsky

compiler/rustc_const_eval/src/interpret/util.rs

@@ -1,12 +1,8 @@
-use std::ops::ControlFlow;
-
 use rustc_hir::def_id::LocalDefId;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{Allocation, InterpResult, Pointer};
 use rustc_middle::ty::layout::TyAndLayout;
-use rustc_middle::ty::{
-    self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor,
-};
+use rustc_middle::ty::{TyCtxt, TypeVisitable, TypeVisitableExt};
 use tracing::debug;
 
 use super::{InterpCx, MPlaceTy, MemoryKind, interp_ok, throw_inval};
@@ -20,44 +16,10 @@ where
     T: TypeVisitable<TyCtxt<'tcx>>,
 {
     debug!("ensure_monomorphic_enough: ty={:?}", ty);
-    if !ty.has_param() {
-        return interp_ok(());
-    }
-
-    struct FoundParam;
-    struct UsedParamsNeedInstantiationVisitor {}
-
-    impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for UsedParamsNeedInstantiationVisitor {
-        type Result = ControlFlow<FoundParam>;
-
-        fn visit_ty(&mut self, ty: Ty<'tcx>) -> Self::Result {
-            if !ty.has_param() {
-                return ControlFlow::Continue(());
-            }
-
-            match *ty.kind() {
-                ty::Param(_) => ControlFlow::Break(FoundParam),
-                ty::Closure(..) | ty::CoroutineClosure(..) | ty::Coroutine(..) | ty::FnDef(..) => {
-                    ControlFlow::Continue(())
-                }
-                _ => ty.super_visit_with(self),
-            }
-        }
-
-        fn visit_const(&mut self, c: ty::Const<'tcx>) -> Self::Result {
-            match c.kind() {
-                ty::ConstKind::Param(..) => ControlFlow::Break(FoundParam),
-                _ => c.super_visit_with(self),
-            }
-        }
-    }
-
-    let mut vis = UsedParamsNeedInstantiationVisitor {};
-    if matches!(ty.visit_with(&mut vis), ControlFlow::Break(FoundParam)) {
+    if ty.has_param() {
         throw_inval!(TooGeneric);
-    } else {
-        interp_ok(())
     }
+    interp_ok(())
 }
 
 impl<'tcx> InterpretationResult<'tcx> for mir::interpret::ConstAllocation<'tcx> {

tests/mir-opt/gvn_type_id_polymorphic.cursed_is_i32.GVN.diff

@@ -5,8 +5,7 @@
       let mut _0: bool;
 
       bb0: {
--         _0 = Eq(const cursed_is_i32::<T>::{constant#0}, const cursed_is_i32::<T>::{constant#1});
-+         _0 = const false;
+          _0 = Eq(const cursed_is_i32::<T>::{constant#0}, const cursed_is_i32::<T>::{constant#1});
           return;
       }
   }

tests/mir-opt/gvn_type_id_polymorphic.rs

@@ -12,7 +12,7 @@ const fn type_id_of_val<T: 'static>(_: &T) -> u128 {
 // EMIT_MIR gvn_type_id_polymorphic.cursed_is_i32.GVN.diff
 fn cursed_is_i32<T: 'static>() -> bool {
     // CHECK-LABEL: fn cursed_is_i32(
-    // CHECK: _0 = const false;
+    // CHECK: _0 = Eq(const cursed_is_i32::<T>::{constant#0}, const cursed_is_i32::<T>::{constant#1});
     // CHECK-NEXT: return;
     (const { type_id_of_val(&generic::<T>) } == const { type_id_of_val(&generic::<i32>) })
 }