Auto merge of #47915 - eddyb:layout-of, r=nikomatsakis

rustc: prefer ParamEnvAnd and LayoutCx over tuples for LayoutOf.

This PR provides `tcx.layout_of(param_env.and(ty))` as the idiomatic replacement for the existing `(tcx, param_env).layout_of(ty)` and removes fragile (coherence-wise) layout-related tuple impls.

r? @nikomatsakis

1 files changed, 1 insertions, 2 deletions

diff --git a/src/librustc_const_eval/eval.rs b/src/librustc_const_eval/eval.rs
index 418bd4b5eff..1d2813e4f67 100644
--- a/src/librustc_const_eval/eval.rs
+++ b/src/librustc_const_eval/eval.rs
@@ -17,7 +17,6 @@ use rustc::hir::map::blocks::FnLikeNode;
 use rustc::hir::def::{Def, CtorKind};
 use rustc::hir::def_id::DefId;
 use rustc::ty::{self, Ty, TyCtxt};
-use rustc::ty::layout::LayoutOf;
 use rustc::ty::util::IntTypeExt;
 use rustc::ty::subst::{Substs, Subst};
 use rustc::util::common::ErrorReported;
@@ -313,7 +312,7 @@ fn eval_const_expr_partial<'a, 'tcx>(cx: &ConstContext<'a, 'tcx>,
           if tcx.fn_sig(def_id).abi() == Abi::RustIntrinsic {
             let layout_of = |ty: Ty<'tcx>| {
                 let ty = tcx.erase_regions(&ty);
-                (tcx.at(e.span), cx.param_env).layout_of(ty).map_err(|err| {
+                tcx.at(e.span).layout_of(cx.param_env.and(ty)).map_err(|err| {
                     ConstEvalErr { span: e.span, kind: LayoutError(err) }
                 })
             };