Remove unnecessary lifetimes in elaborator structs.

Starting with `ElaborateDropsCtxt`, which then leads to `Elaborator`.

Author: nnethercote

compiler/rustc_mir_transform/src/elaborate_drops.rs

@@ -137,24 +137,24 @@ impl InitializationData<'_, '_> {
     }
 }
 
-struct Elaborator<'a, 'b, 'mir, 'tcx> {
-    ctxt: &'a mut ElaborateDropsCtxt<'b, 'mir, 'tcx>,
+struct Elaborator<'a, 'mir, 'tcx> {
+    ctxt: &'a mut ElaborateDropsCtxt<'mir, 'tcx>,
 }
 
-impl fmt::Debug for Elaborator<'_, '_, '_, '_> {
+impl fmt::Debug for Elaborator<'_, '_, '_> {
     fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
         Ok(())
     }
 }
 
-impl<'a, 'tcx> DropElaborator<'a, 'tcx> for Elaborator<'a, '_, '_, 'tcx> {
+impl<'mir, 'tcx> DropElaborator<'mir, 'tcx> for Elaborator<'_, 'mir, 'tcx> {
     type Path = MovePathIndex;
 
     fn patch(&mut self) -> &mut MirPatch<'tcx> {
         &mut self.ctxt.patch
     }
 
-    fn body(&self) -> &'a Body<'tcx> {
+    fn body(&self) -> &'mir Body<'tcx> {
         self.ctxt.body
     }
 
@@ -241,17 +241,17 @@ impl<'a, 'tcx> DropElaborator<'a, 'tcx> for Elaborator<'a, '_, '_, 'tcx> {
     }
 }
 
-struct ElaborateDropsCtxt<'a, 'mir, 'tcx> {
+struct ElaborateDropsCtxt<'mir, 'tcx> {
     tcx: TyCtxt<'tcx>,
     body: &'mir Body<'tcx>,
-    env: &'a MoveDataParamEnv<'tcx>,
+    env: &'mir MoveDataParamEnv<'tcx>,
     init_data: InitializationData<'mir, 'tcx>,
     drop_flags: IndexVec<MovePathIndex, Option<Local>>,
     patch: MirPatch<'tcx>,
 }
 
-impl<'b, 'mir, 'tcx> ElaborateDropsCtxt<'b, 'mir, 'tcx> {
-    fn move_data(&self) -> &'b MoveData<'tcx> {
+impl<'mir, 'tcx> ElaborateDropsCtxt<'mir, 'tcx> {
+    fn move_data(&self) -> &'mir MoveData<'tcx> {
         &self.env.move_data
     }