Auto merge of rust-lang#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

src/librustc/lint/context.rs

@@ -631,7 +631,7 @@ impl<'a, 'tcx> LayoutOf<Ty<'tcx>> for &'a LateContext<'a, 'tcx> {
     type TyLayout = Result<TyLayout<'tcx>, LayoutError<'tcx>>;
 
     fn layout_of(self, ty: Ty<'tcx>) -> Self::TyLayout {
-        (self.tcx, self.param_env.reveal_all()).layout_of(ty)
+        self.tcx.layout_of(self.param_env.and(ty))
     }
 }
 

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) }
                 })
             };

src/librustc_lint/types.rs

@@ -437,8 +437,8 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                             // repr(transparent) types are allowed to have arbitrary ZSTs, not just
                             // PhantomData -- skip checking all ZST fields
                             if def.repr.transparent() {
-                                let is_zst = (cx, cx.param_env(field.did))
-                                    .layout_of(field_ty)
+                                let is_zst = cx
+                                    .layout_of(cx.param_env(field.did).and(field_ty))
                                     .map(|layout| layout.is_zst())
                                     .unwrap_or(false);
                                 if is_zst {

src/librustc_mir/interpret/eval_context.rs

@@ -172,7 +172,7 @@ impl<'a, 'tcx, M: Machine<'tcx>> LayoutOf<Ty<'tcx>> for &'a EvalContext<'a, 'tcx
     type TyLayout = EvalResult<'tcx, TyLayout<'tcx>>;
 
     fn layout_of(self, ty: Ty<'tcx>) -> Self::TyLayout {
-        (self.tcx, self.param_env).layout_of(ty)
+        self.tcx.layout_of(self.param_env.and(ty))
             .map_err(|layout| EvalErrorKind::Layout(layout).into())
     }
 }

src/librustc_mir/transform/inline.rs

@@ -19,7 +19,6 @@ use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 use rustc::mir::*;
 use rustc::mir::visit::*;
 use rustc::ty::{self, Instance, Ty, TyCtxt, TypeFoldable};
-use rustc::ty::layout::LayoutOf;
 use rustc::ty::subst::{Subst,Substs};
 
 use std::collections::VecDeque;
@@ -655,7 +654,7 @@ impl<'a, 'tcx> Inliner<'a, 'tcx> {
 fn type_size_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                           param_env: ty::ParamEnv<'tcx>,
                           ty: Ty<'tcx>) -> Option<u64> {
-    (tcx, param_env).layout_of(ty).ok().map(|layout| layout.size.bytes())
+    tcx.layout_of(param_env.and(ty)).ok().map(|layout| layout.size.bytes())
 }
 
 fn subst_and_normalize<'a, 'tcx: 'a>(

src/librustc_trans/context.rs

@@ -464,8 +464,7 @@ impl<'a, 'tcx> LayoutOf<Ty<'tcx>> for &'a CodegenCx<'a, 'tcx> {
     type TyLayout = TyLayout<'tcx>;
 
     fn layout_of(self, ty: Ty<'tcx>) -> Self::TyLayout {
-        (self.tcx, ty::ParamEnv::empty(traits::Reveal::All))
-            .layout_of(ty)
+        self.tcx.layout_of(ty::ParamEnv::empty(traits::Reveal::All).and(ty))
             .unwrap_or_else(|e| match e {
                 LayoutError::SizeOverflow(_) => self.sess().fatal(&e.to_string()),
                 _ => bug!("failed to get layout for `{}`: {}", ty, e)

src/librustc_typeck/check/mod.rs

@@ -100,7 +100,6 @@ use rustc::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
 use rustc::ty::fold::TypeFoldable;
 use rustc::ty::maps::Providers;
 use rustc::ty::util::{Representability, IntTypeExt};
-use rustc::ty::layout::LayoutOf;
 use errors::{DiagnosticBuilder, DiagnosticId};
 
 use require_c_abi_if_variadic;
@@ -1553,7 +1552,7 @@ fn check_transparent<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, sp: Span, def_id: De
     let field_infos: Vec<_> = adt.non_enum_variant().fields.iter().map(|field| {
         let ty = field.ty(tcx, Substs::identity_for_item(tcx, field.did));
         let param_env = tcx.param_env(field.did);
-        let layout = (tcx, param_env).layout_of(ty);
+        let layout = tcx.layout_of(param_env.and(ty));
         // We are currently checking the type this field came from, so it must be local
         let span = tcx.hir.span_if_local(field.did).unwrap();
         let zst = layout.map(|layout| layout.is_zst()).unwrap_or(false);