use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::{self, BasicBlock, Location};
use rustc_middle::ty::{Ty, TyCtxt};
use rustc_span::{symbol::sym, Span};
use super::check::Qualifs;
use super::ops::{self, NonConstOp};
use super::qualifs::{NeedsDrop, Qualif};
use super::ConstCx;
pub fn checking_enabled(ccx: &ConstCx<'_, '_>) -> bool {
if ccx.is_const_stable_const_fn() {
return false;
}
ccx.tcx.features().const_precise_live_drops
}
pub fn check_live_drops<'tcx>(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;
}
if tcx.has_attr(def_id, sym::rustc_do_not_const_check) {
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>,
}
impl<'mir, 'tcx> std::ops::Deref for CheckLiveDrops<'mir, 'tcx> {
type Target = ConstCx<'mir, 'tcx>;
fn deref(&self) -> &Self::Target {
&self.ccx
}
}
impl<'tcx> CheckLiveDrops<'_, 'tcx> {
fn check_live_drop(&self, span: Span, dropped_ty: Ty<'tcx>) {
ops::LiveDrop { dropped_at: None, dropped_ty }.build_error(self.ccx, span).emit();
}
}
impl<'tcx> Visitor<'tcx> for CheckLiveDrops<'_, '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);
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) {
return;
}
if dropped_place.is_indirect() {
self.check_live_drop(terminator.source_info.span, dropped_ty);
return;
}
if self.qualifs.needs_non_const_drop(self.ccx, dropped_place.local, location) {
let span = self.body.local_decls[dropped_place.local].source_info.span;
self.check_live_drop(span, dropped_ty);
}
}
mir::TerminatorKind::UnwindTerminate(_)
| mir::TerminatorKind::Call { .. }
| mir::TerminatorKind::Assert { .. }
| mir::TerminatorKind::FalseEdge { .. }
| mir::TerminatorKind::FalseUnwind { .. }
| mir::TerminatorKind::GeneratorDrop
| mir::TerminatorKind::Goto { .. }
| mir::TerminatorKind::InlineAsm { .. }
| mir::TerminatorKind::UnwindResume
| mir::TerminatorKind::Return
| mir::TerminatorKind::SwitchInt { .. }
| mir::TerminatorKind::Unreachable
| mir::TerminatorKind::Yield { .. } => {}
}
}
}