interpret: reduce usage of TypingEnv::fully_monomorphized

Author: RalfJung

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -248,10 +248,9 @@ impl<'tcx> CompileTimeInterpCx<'tcx> {
         } else if self.tcx.is_lang_item(def_id, LangItem::PanicFmt) {
             // For panic_fmt, call const_panic_fmt instead.
             let const_def_id = self.tcx.require_lang_item(LangItem::ConstPanicFmt, None);
-            // FIXME(@lcnr): why does this use an empty env if we've got a `param_env` right here.
             let new_instance = ty::Instance::expect_resolve(
                 *self.tcx,
-                ty::TypingEnv::fully_monomorphized(),
+                self.typing_env(),
                 const_def_id,
                 instance.args,
                 self.cur_span(),

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -297,6 +297,7 @@ impl<'tcx, Prov: Provenance> ImmTy<'tcx, Prov> {
 
     #[inline]
     pub fn from_bool(b: bool, tcx: TyCtxt<'tcx>) -> Self {
+        // Can use any typing env, since `bool` is always monomorphic.
         let layout = tcx
             .layout_of(ty::TypingEnv::fully_monomorphized().as_query_input(tcx.types.bool))
             .unwrap();
@@ -305,17 +306,18 @@ impl<'tcx, Prov: Provenance> ImmTy<'tcx, Prov> {
 
     #[inline]
     pub fn from_ordering(c: std::cmp::Ordering, tcx: TyCtxt<'tcx>) -> Self {
+        // Can use any typing env, since `Ordering` is always monomorphic.
         let ty = tcx.ty_ordering_enum(None);
         let layout =
             tcx.layout_of(ty::TypingEnv::fully_monomorphized().as_query_input(ty)).unwrap();
         Self::from_scalar(Scalar::from_i8(c as i8), layout)
     }
 
-    pub fn from_pair(a: Self, b: Self, tcx: TyCtxt<'tcx>) -> Self {
-        let layout = tcx
+    pub fn from_pair(a: Self, b: Self, cx: &(impl HasTypingEnv<'tcx> + HasTyCtxt<'tcx>)) -> Self {
+        let layout = cx
+            .tcx()
             .layout_of(
-                ty::TypingEnv::fully_monomorphized()
-                    .as_query_input(Ty::new_tup(tcx, &[a.layout.ty, b.layout.ty])),
+                cx.typing_env().as_query_input(Ty::new_tup(cx.tcx(), &[a.layout.ty, b.layout.ty])),
             )
             .unwrap();
         Self::from_scalar_pair(a.to_scalar(), b.to_scalar(), layout)

compiler/rustc_const_eval/src/interpret/operator.rs

@@ -222,7 +222,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 let res = ImmTy::from_scalar_int(result, left.layout);
                 return interp_ok(if with_overflow {
                     let overflow = ImmTy::from_bool(overflow, *self.tcx);
-                    ImmTy::from_pair(res, overflow, *self.tcx)
+                    ImmTy::from_pair(res, overflow, self)
                 } else {
                     res
                 });
@@ -279,7 +279,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 let res = ImmTy::from_scalar_int(result, left.layout);
                 if with_overflow {
                     let overflow = ImmTy::from_bool(overflow, *self.tcx);
-                    ImmTy::from_pair(res, overflow, *self.tcx)
+                    ImmTy::from_pair(res, overflow, self)
                 } else {
                     res
                 }