Use associative type defaults in `{Layout,FnAbi}OfHelpers`.

This avoids some repetitive boilerplate code.

2 files changed, 3 insertions, 2 deletions

diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index fd6e2ad79b1..23cd247e884 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -33,6 +33,7 @@
 #![feature(allocator_api)]
 #![feature(array_windows)]
 #![feature(assert_matches)]
+#![feature(associated_type_defaults)]
 #![feature(box_as_ptr)]
 #![feature(box_patterns)]
 #![feature(closure_track_caller)]
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 254a0119920..c9a492936b0 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -634,7 +634,7 @@ pub type TyAndLayout<'tcx> = rustc_target::abi::TyAndLayout<'tcx, Ty<'tcx>>;
 pub trait LayoutOfHelpers<'tcx>: HasDataLayout + HasTyCtxt<'tcx> + HasParamEnv<'tcx> {
     /// The `TyAndLayout`-wrapping type (or `TyAndLayout` itself), which will be
     /// returned from `layout_of` (see also `handle_layout_err`).
-    type LayoutOfResult: MaybeResult<TyAndLayout<'tcx>>;
+    type LayoutOfResult: MaybeResult<TyAndLayout<'tcx>> = TyAndLayout<'tcx>;
 
     /// `Span` to use for `tcx.at(span)`, from `layout_of`.
     // FIXME(eddyb) perhaps make this mandatory to get contexts to track it better?
@@ -1259,7 +1259,7 @@ pub enum FnAbiRequest<'tcx> {
 pub trait FnAbiOfHelpers<'tcx>: LayoutOfHelpers<'tcx> {
     /// The `&FnAbi`-wrapping type (or `&FnAbi` itself), which will be
     /// returned from `fn_abi_of_*` (see also `handle_fn_abi_err`).
-    type FnAbiOfResult: MaybeResult<&'tcx FnAbi<'tcx, Ty<'tcx>>>;
+    type FnAbiOfResult: MaybeResult<&'tcx FnAbi<'tcx, Ty<'tcx>>> = &'tcx FnAbi<'tcx, Ty<'tcx>>;
 
     /// Helper used for `fn_abi_of_*`, to adapt `tcx.fn_abi_of_*(...)` into a
     /// `Self::FnAbiOfResult` (which does not need to be a `Result<...>`).