New upstream version 1.57.0+dfsg1

[rustc.git] / compiler / rustc_mir / src / transform / check_consts / post_drop_elaboration.rs

diff --git a/compiler/rustc_mir/src/transform/check_consts/post_drop_elaboration.rs b/compiler/rustc_mir/src/transform/check_consts/post_drop_elaboration.rs
deleted file mode 100644 (file)
index b08ce21..0000000
--- a/compiler/rustc_mir/src/transform/check_consts/post_drop_elaboration.rs
+++ /dev/null
@@ -1,123 +0,0 @@
-use rustc_middle::mir::visit::Visitor;
-use rustc_middle::mir::{self, BasicBlock, Location};
-use rustc_middle::ty::TyCtxt;
-use rustc_span::Span;
-
-use super::check::Qualifs;
-use super::ops::{self, NonConstOp};
-use super::qualifs::{NeedsDrop, Qualif};
-use super::ConstCx;
-
-/// Returns `true` if we should use the more precise live drop checker that runs after drop
-/// elaboration.
-pub fn checking_enabled(ccx: &ConstCx<'_, '_>) -> bool {
-    // Const-stable functions must always use the stable live drop checker.
-    if ccx.is_const_stable_const_fn() {
-        return false;
-    }
-
-    ccx.tcx.features().const_precise_live_drops
-}
-
-/// Look for live drops in a const context.
-///
-/// This is separate from the rest of the const checking logic because it must run after drop
-/// elaboration.
-pub fn check_live_drops(tcx: TyCtxt<'tcx>, body: &mir::Body<'tcx>) {
-    let def_id = body.source.def_id().expect_local();
-    let const_kind = tcx.hir().body_const_context(def_id);
-    if const_kind.is_none() {
-        return;
-    }
-
-    let ccx = ConstCx { body, tcx, const_kind, param_env: tcx.param_env(def_id) };
-    if !checking_enabled(&ccx) {
-        return;
-    }
-
-    let mut visitor = CheckLiveDrops { ccx: &ccx, qualifs: Qualifs::default() };
-
-    visitor.visit_body(body);
-}
-
-struct CheckLiveDrops<'mir, 'tcx> {
-    ccx: &'mir ConstCx<'mir, 'tcx>,
-    qualifs: Qualifs<'mir, 'tcx>,
-}
-
-// So we can access `body` and `tcx`.
-impl std::ops::Deref for CheckLiveDrops<'mir, 'tcx> {
-    type Target = ConstCx<'mir, 'tcx>;
-
-    fn deref(&self) -> &Self::Target {
-        &self.ccx
-    }
-}
-
-impl CheckLiveDrops<'mir, 'tcx> {
-    fn check_live_drop(&self, span: Span) {
-        ops::LiveDrop { dropped_at: None }.build_error(self.ccx, span).emit();
-    }
-}
-
-impl Visitor<'tcx> for CheckLiveDrops<'mir, 'tcx> {
-    fn visit_basic_block_data(&mut self, bb: BasicBlock, block: &mir::BasicBlockData<'tcx>) {
-        trace!("visit_basic_block_data: bb={:?} is_cleanup={:?}", bb, block.is_cleanup);
-
-        // Ignore drop terminators in cleanup blocks.
-        if block.is_cleanup {
-            return;
-        }
-
-        self.super_basic_block_data(bb, block);
-    }
-
-    fn visit_terminator(&mut self, terminator: &mir::Terminator<'tcx>, location: Location) {
-        trace!("visit_terminator: terminator={:?} location={:?}", terminator, location);
-
-        match &terminator.kind {
-            mir::TerminatorKind::Drop { place: dropped_place, .. } => {
-                let dropped_ty = dropped_place.ty(self.body, self.tcx).ty;
-                if !NeedsDrop::in_any_value_of_ty(self.ccx, dropped_ty) {
-                    bug!(
-                        "Drop elaboration left behind a Drop for a type that does not need dropping"
-                    );
-                }
-
-                if dropped_place.is_indirect() {
-                    self.check_live_drop(terminator.source_info.span);
-                    return;
-                }
-
-                // Drop elaboration is not precise enough to accept code like
-                // `src/test/ui/consts/control-flow/drop-pass.rs`; e.g., when an `Option<Vec<T>>` is
-                // initialized with `None` and never changed, it still emits drop glue.
-                // Hence we additionally check the qualifs here to allow more code to pass.
-                if self.qualifs.needs_drop(self.ccx, dropped_place.local, location) {
-                    // Use the span where the dropped local was declared for the error.
-                    let span = self.body.local_decls[dropped_place.local].source_info.span;
-                    self.check_live_drop(span);
-                }
-            }
-
-            mir::TerminatorKind::DropAndReplace { .. } => span_bug!(
-                terminator.source_info.span,
-                "`DropAndReplace` should be removed by drop elaboration",
-            ),
-
-            mir::TerminatorKind::Abort
-            | mir::TerminatorKind::Call { .. }
-            | mir::TerminatorKind::Assert { .. }
-            | mir::TerminatorKind::FalseEdge { .. }
-            | mir::TerminatorKind::FalseUnwind { .. }
-            | mir::TerminatorKind::GeneratorDrop
-            | mir::TerminatorKind::Goto { .. }
-            | mir::TerminatorKind::InlineAsm { .. }
-            | mir::TerminatorKind::Resume
-            | mir::TerminatorKind::Return
-            | mir::TerminatorKind::SwitchInt { .. }
-            | mir::TerminatorKind::Unreachable
-            | mir::TerminatorKind::Yield { .. } => {}
-        }
-    }
-}