Use in-band-lifetimes instead of unused explicit lifetimes

Author: oli-obk

src/librustc/lib.rs

@@ -68,6 +68,7 @@
 #![feature(trusted_len)]
 #![feature(catch_expr)]
 #![feature(test)]
+#![feature(in_band_lifetimes)]
 
 #![recursion_limit="512"]
 

src/librustc/ty/layout.rs

@@ -1513,7 +1513,7 @@ impl<'a, 'tcx> LayoutOf for LayoutCx<'tcx, ty::maps::TyCtxtAt<'a, 'tcx, 'tcx>> {
 }
 
 // Helper (inherent) `layout_of` methods to avoid pushing `LayoutCx` to users.
-impl<'a, 'tcx, 'empty> TyCtxt<'a, 'tcx, 'empty> {
+impl TyCtxt<'a, 'tcx, '_> {
     /// Computes the layout of a type. Note that this implicitly
     /// executes in "reveal all" mode.
     #[inline]
@@ -1527,7 +1527,7 @@ impl<'a, 'tcx, 'empty> TyCtxt<'a, 'tcx, 'empty> {
     }
 }
 
-impl<'a, 'tcx, 'empty> ty::maps::TyCtxtAt<'a, 'tcx, 'empty> {
+impl ty::maps::TyCtxtAt<'a, 'tcx, '_> {
     /// Computes the layout of a type. Note that this implicitly
     /// executes in "reveal all" mode.
     #[inline]