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use rustc::ty::subst::Substs;
use rustc::ty::{self, Ty, TyCtxt};
use rustc::mir::*;
use rustc::mir::visit::{MutVisitor, TyContext};
use transform::{MirPass, MirSource};
struct EraseRegionsVisitor<'a, 'tcx: 'a> {
tcx: TyCtxt<'a, 'tcx, 'tcx>,
in_validation_statement: bool,
}
impl<'a, 'tcx> EraseRegionsVisitor<'a, 'tcx> {
pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Self {
EraseRegionsVisitor {
tcx,
in_validation_statement: false,
}
}
}
impl<'a, 'tcx> MutVisitor<'tcx> for EraseRegionsVisitor<'a, 'tcx> {
fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) {
if !self.in_validation_statement {
*ty = self.tcx.erase_regions(ty);
}
self.super_ty(ty);
}
fn visit_region(&mut self, region: &mut ty::Region<'tcx>, _: Location) {
*region = self.tcx.types.re_erased;
}
fn visit_const(&mut self, constant: &mut &'tcx ty::Const<'tcx>, _: Location) {
*constant = self.tcx.erase_regions(constant);
}
fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>, _: Location) {
*substs = self.tcx.erase_regions(substs);
}
fn visit_statement(&mut self,
block: BasicBlock,
statement: &mut Statement<'tcx>,
location: Location) {
if self.tcx.sess.opts.debugging_opts.mir_emit_validate == 0 {
if let StatementKind::EndRegion(_) = statement.kind {
statement.kind = StatementKind::Nop;
}
}
self.in_validation_statement = match statement.kind {
StatementKind::Validate(..) => true,
_ => false,
};
self.super_statement(block, statement, location);
self.in_validation_statement = false;
}
}
pub struct EraseRegions;
impl MirPass for EraseRegions {
fn run_pass<'a, 'tcx>(&self,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
_: MirSource,
mir: &mut Mir<'tcx>) {
EraseRegionsVisitor::new(tcx).visit_mir(mir);
}
}