Move some supertraits outward.

Specifically, put them where they are genuinely required, i.e. the
outermost place they can be.

Author: nnethercote

compiler/rustc_codegen_ssa/src/mir/operand.rs

@@ -280,7 +280,7 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
     ///
     /// If you don't need the type, see [`OperandValue::pointer_parts`]
     /// or [`OperandValue::deref`].
-    pub fn deref<Cx: LayoutTypeMethods<'tcx>>(self, cx: &Cx) -> PlaceRef<'tcx, V> {
+    pub fn deref<Cx: CodegenMethods<'tcx>>(self, cx: &Cx) -> PlaceRef<'tcx, V> {
         if self.layout.ty.is_box() {
             // Derefer should have removed all Box derefs
             bug!("dereferencing {:?} in codegen", self.layout.ty);

compiler/rustc_codegen_ssa/src/traits/mod.rs

@@ -27,6 +27,11 @@ mod write;
 
 use std::fmt;
 
+use rustc_middle::ty::layout::FnAbiOf;
+use rustc_middle::ty::Ty;
+use rustc_target::abi::call::FnAbi;
+use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
+
 pub use self::abi::AbiBuilderMethods;
 pub use self::asm::{AsmBuilderMethods, AsmMethods, GlobalAsmOperandRef, InlineAsmOperandRef};
 pub use self::backend::{BackendTypes, CodegenBackend, ExtraBackendMethods};
@@ -46,7 +51,9 @@ pub use self::write::{ModuleBufferMethods, ThinBufferMethods, WriteBackendMethod
 
 pub trait CodegenObject = Copy + PartialEq + fmt::Debug;
 
-pub trait CodegenMethods<'tcx> = TypeMethods<'tcx>
+pub trait CodegenMethods<'tcx> = LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>>
+    + FnAbiOf<'tcx, FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>>
+    + TypeMethods<'tcx>
     + ConstMethods<'tcx>
     + StaticMethods
     + DebugInfoMethods<'tcx>

compiler/rustc_codegen_ssa/src/traits/type_.rs

@@ -1,5 +1,5 @@
 use rustc_middle::bug;
-use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf, TyAndLayout};
+use rustc_middle::ty::layout::{HasTyCtxt, TyAndLayout};
 use rustc_middle::ty::{self, Ty};
 use rustc_target::abi::call::{ArgAbi, CastTarget, FnAbi, Reg};
 use rustc_target::abi::{AddressSpace, Float, Integer};
@@ -9,7 +9,7 @@ use super::BackendTypes;
 use crate::common::TypeKind;
 use crate::mir::place::PlaceRef;
 
-pub trait BaseTypeMethods<'tcx>: BackendTypes + HasTyCtxt<'tcx> {
+pub trait BaseTypeMethods<'tcx>: BackendTypes {
     fn type_i8(&self) -> Self::Type;
     fn type_i16(&self) -> Self::Type;
     fn type_i32(&self) -> Self::Type;
@@ -40,7 +40,9 @@ pub trait BaseTypeMethods<'tcx>: BackendTypes + HasTyCtxt<'tcx> {
     fn val_ty(&self, v: Self::Value) -> Self::Type;
 }
 
-pub trait DerivedTypeMethods<'tcx>: BaseTypeMethods<'tcx> + MiscMethods<'tcx> {
+pub trait DerivedTypeMethods<'tcx>:
+    BaseTypeMethods<'tcx> + MiscMethods<'tcx> + HasTyCtxt<'tcx>
+{
     fn type_int(&self) -> Self::Type {
         match &self.sess().target.c_int_width[..] {
             "16" => self.type_i16(),
@@ -98,13 +100,12 @@ pub trait DerivedTypeMethods<'tcx>: BaseTypeMethods<'tcx> + MiscMethods<'tcx> {
     }
 }
 
-impl<'tcx, T> DerivedTypeMethods<'tcx> for T where Self: BaseTypeMethods<'tcx> + MiscMethods<'tcx> {}
-
-pub trait LayoutTypeMethods<'tcx>:
-    BackendTypes
-    + LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>>
-    + FnAbiOf<'tcx, FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>>
+impl<'tcx, T> DerivedTypeMethods<'tcx> for T where
+    Self: BaseTypeMethods<'tcx> + MiscMethods<'tcx> + HasTyCtxt<'tcx>
 {
+}
+
+pub trait LayoutTypeMethods<'tcx>: BackendTypes {
     /// The backend type used for a rust type when it's in memory,
     /// such as when it's stack-allocated or when it's being loaded or stored.
     fn backend_type(&self, layout: TyAndLayout<'tcx>) -> Self::Type;