Use trait aliases to shorten some code.

Author: nnethercote

compiler/rustc_codegen_ssa/src/lib.rs

@@ -11,6 +11,7 @@
 #![feature(negative_impls)]
 #![feature(rustdoc_internals)]
 #![feature(strict_provenance)]
+#![feature(trait_alias)]
 #![feature(try_blocks)]
 #![warn(unreachable_pub)]
 // tidy-alphabetical-end

compiler/rustc_codegen_ssa/src/traits/backend.rs

@@ -36,22 +36,11 @@ pub trait BackendTypes {
     type DIVariable: Copy;
 }
 
-pub trait Backend<'tcx>:
-    Sized
+pub trait Backend<'tcx> = Sized
     + BackendTypes
     + HasTyCtxt<'tcx>
     + LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>>
-    + FnAbiOf<'tcx, FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>>
-{
-}
-
-impl<'tcx, T> Backend<'tcx> for T where
-    Self: BackendTypes
-        + HasTyCtxt<'tcx>
-        + LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>>
-        + FnAbiOf<'tcx, FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>>
-{
-}
+    + FnAbiOf<'tcx, FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>>;
 
 pub trait CodegenBackend {
     /// Locale resources for diagnostic messages - a string the content of the Fluent resource.

compiler/rustc_codegen_ssa/src/traits/mod.rs

@@ -50,11 +50,9 @@ pub use self::type_::{
 };
 pub use self::write::{ModuleBufferMethods, ThinBufferMethods, WriteBackendMethods};
 
-pub trait CodegenObject: Copy + PartialEq + fmt::Debug {}
-impl<T: Copy + PartialEq + fmt::Debug> CodegenObject for T {}
+pub trait CodegenObject = Copy + PartialEq + fmt::Debug;
 
-pub trait CodegenMethods<'tcx>:
-    Backend<'tcx>
+pub trait CodegenMethods<'tcx> = Backend<'tcx>
     + TypeMethods<'tcx>
     + MiscMethods<'tcx>
     + ConstMethods<'tcx>
@@ -64,24 +62,7 @@ pub trait CodegenMethods<'tcx>:
     + PreDefineMethods<'tcx>
     + HasParamEnv<'tcx>
     + HasTyCtxt<'tcx>
-    + HasTargetSpec
-{
-}
-
-impl<'tcx, T> CodegenMethods<'tcx> for T where
-    Self: Backend<'tcx>
-        + TypeMethods<'tcx>
-        + MiscMethods<'tcx>
-        + ConstMethods<'tcx>
-        + StaticMethods
-        + DebugInfoMethods<'tcx>
-        + AsmMethods<'tcx>
-        + PreDefineMethods<'tcx>
-        + HasParamEnv<'tcx>
-        + HasTyCtxt<'tcx>
-        + HasTargetSpec
-{
-}
+    + HasTargetSpec;
 
 pub trait HasCodegen<'tcx>:
     Backend<'tcx> + std::ops::Deref<Target = <Self as HasCodegen<'tcx>>::CodegenCx>

compiler/rustc_codegen_ssa/src/traits/type_.rs

@@ -172,12 +172,5 @@ pub trait ArgAbiMethods<'tcx>: HasCodegen<'tcx> {
     fn arg_memory_ty(&self, arg_abi: &ArgAbi<'tcx, Ty<'tcx>>) -> Self::Type;
 }
 
-pub trait TypeMethods<'tcx>:
-    DerivedTypeMethods<'tcx> + LayoutTypeMethods<'tcx> + TypeMembershipMethods<'tcx>
-{
-}
-
-impl<'tcx, T> TypeMethods<'tcx> for T where
-    Self: DerivedTypeMethods<'tcx> + LayoutTypeMethods<'tcx> + TypeMembershipMethods<'tcx>
-{
-}
+pub trait TypeMethods<'tcx> =
+    DerivedTypeMethods<'tcx> + LayoutTypeMethods<'tcx> + TypeMembershipMethods<'tcx>;