Rollup merge of #108856 - Zeegomo:remove-drop-and-rep, r=tmiasko

Remove DropAndReplace terminator

#107844 made DropAndReplace unused, let's remove it completely from the codebase.

Author: matthiaskrgr

compiler/rustc_borrowck/src/invalidation.rs

@@ -118,15 +118,6 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                     LocalMutationIsAllowed::Yes,
                 );
             }
-            TerminatorKind::DropAndReplace {
-                place: drop_place,
-                value: new_value,
-                target: _,
-                unwind: _,
-            } => {
-                self.mutate_place(location, *drop_place, Deep);
-                self.consume_operand(location, new_value);
-            }
             TerminatorKind::Call {
                 func,
                 args,

compiler/rustc_borrowck/src/lib.rs

@@ -743,15 +743,6 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
                     flow_state,
                 );
             }
-            TerminatorKind::DropAndReplace {
-                place: drop_place,
-                value: new_value,
-                target: _,
-                unwind: _,
-            } => {
-                self.mutate_place(loc, (*drop_place, span), Deep, flow_state);
-                self.consume_operand(loc, (new_value, span), flow_state);
-            }
             TerminatorKind::Call {
                 func,
                 args,
@@ -866,7 +857,6 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
             | TerminatorKind::Assert { .. }
             | TerminatorKind::Call { .. }
             | TerminatorKind::Drop { .. }
-            | TerminatorKind::DropAndReplace { .. }
             | TerminatorKind::FalseEdge { real_target: _, imaginary_target: _ }
             | TerminatorKind::FalseUnwind { real_target: _, unwind: _ }
             | TerminatorKind::Goto { .. }

compiler/rustc_borrowck/src/type_check/liveness/trace.rs

@@ -435,8 +435,7 @@ impl<'me, 'typeck, 'flow, 'tcx> LivenessResults<'me, 'typeck, 'flow, 'tcx> {
         //
         // What we *actually* generate is a store to a temporary
         // for the call (`TMP = call()...`) and then a
-        // `DropAndReplace` to swap that with `X`
-        // (`DropAndReplace` has very particular semantics).
+        // `Drop(X)` followed by `X = TMP`  to swap that with `X`.
     }
 }
 

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1312,24 +1312,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 // no checks needed for these
             }
 
-            TerminatorKind::DropAndReplace { place, value, target: _, unwind: _ } => {
-                let place_ty = place.ty(body, tcx).ty;
-                let rv_ty = value.ty(body, tcx);
-
-                let locations = term_location.to_locations();
-                if let Err(terr) =
-                    self.sub_types(rv_ty, place_ty, locations, ConstraintCategory::Assignment)
-                {
-                    span_mirbug!(
-                        self,
-                        term,
-                        "bad DropAndReplace ({:?} = {:?}): {:?}",
-                        place_ty,
-                        rv_ty,
-                        terr
-                    );
-                }
-            }
             TerminatorKind::SwitchInt { discr, .. } => {
                 self.check_operand(discr, term_location);
 
@@ -1629,7 +1611,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             }
             TerminatorKind::Unreachable => {}
             TerminatorKind::Drop { target, unwind, .. }
-            | TerminatorKind::DropAndReplace { target, unwind, .. }
             | TerminatorKind::Assert { target, cleanup: unwind, .. } => {
                 self.assert_iscleanup(body, block_data, target, is_cleanup);
                 if let Some(unwind) = unwind {

compiler/rustc_borrowck/src/used_muts.rs

@@ -71,9 +71,6 @@ impl<'visit, 'cx, 'tcx> Visitor<'tcx> for GatherUsedMutsVisitor<'visit, 'cx, 'tc
             TerminatorKind::Call { destination, .. } => {
                 self.remove_never_initialized_mut_locals(*destination);
             }
-            TerminatorKind::DropAndReplace { place, .. } => {
-                self.remove_never_initialized_mut_locals(*place);
-            }
             _ => {}
         }
 

compiler/rustc_codegen_cranelift/src/base.rs

@@ -499,7 +499,6 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
             TerminatorKind::Yield { .. }
             | TerminatorKind::FalseEdge { .. }
             | TerminatorKind::FalseUnwind { .. }
-            | TerminatorKind::DropAndReplace { .. }
             | TerminatorKind::GeneratorDrop => {
                 bug!("shouldn't exist at codegen {:?}", bb_data.terminator());
             }

compiler/rustc_codegen_cranelift/src/constant.rs

@@ -543,8 +543,7 @@ pub(crate) fn mir_operand_get_const_val<'tcx>(
                     | TerminatorKind::Unreachable
                     | TerminatorKind::Drop { .. }
                     | TerminatorKind::Assert { .. } => {}
-                    TerminatorKind::DropAndReplace { .. }
-                    | TerminatorKind::Yield { .. }
+                    TerminatorKind::Yield { .. }
                     | TerminatorKind::GeneratorDrop
                     | TerminatorKind::FalseEdge { .. }
                     | TerminatorKind::FalseUnwind { .. } => unreachable!(),

compiler/rustc_codegen_ssa/src/mir/analyze.rs

@@ -295,7 +295,6 @@ pub fn cleanup_kinds(mir: &mir::Body<'_>) -> IndexVec<mir::BasicBlock, CleanupKi
                 TerminatorKind::Call { cleanup: unwind, .. }
                 | TerminatorKind::InlineAsm { cleanup: unwind, .. }
                 | TerminatorKind::Assert { cleanup: unwind, .. }
-                | TerminatorKind::DropAndReplace { unwind, .. }
                 | TerminatorKind::Drop { unwind, .. } => {
                     if let Some(unwind) = unwind {
                         debug!(

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -1305,10 +1305,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     mergeable_succ(),
                 ),
 
-            mir::TerminatorKind::DropAndReplace { .. } => {
-                bug!("undesugared DropAndReplace in codegen: {:?}", terminator);
-            }
-
             mir::TerminatorKind::Call {
                 ref func,
                 ref args,

compiler/rustc_const_eval/src/interpret/terminator.rs

@@ -171,11 +171,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             Unreachable => throw_ub!(Unreachable),
 
             // These should never occur for MIR we actually run.
-            DropAndReplace { .. }
-            | FalseEdge { .. }
-            | FalseUnwind { .. }
-            | Yield { .. }
-            | GeneratorDrop => span_bug!(
+            FalseEdge { .. } | FalseUnwind { .. } | Yield { .. } | GeneratorDrop => span_bug!(
                 terminator.source_info.span,
                 "{:#?} should have been eliminated by MIR pass",
                 terminator.kind