| //! This pass erases all early-bound regions from the types occurring in the MIR. |
| //! We want to do this once just before codegen, so codegen does not have to take |
| //! care erasing regions all over the place. |
| //! N.B., we do _not_ erase regions of statements that are relevant for |
| //! "types-as-contracts"-validation, namely, `AcquireValid` and `ReleaseValid`. |
| |
| use rustc::ty::subst::SubstsRef; |
| use rustc::ty::{self, Ty, TyCtxt}; |
| use rustc::mir::*; |
| use rustc::mir::visit::{MutVisitor, TyContext}; |
| use crate::transform::{MirPass, MirSource}; |
| |
| struct EraseRegionsVisitor<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| } |
| |
| impl EraseRegionsVisitor<'tcx> { |
| pub fn new(tcx: TyCtxt<'tcx>) -> Self { |
| EraseRegionsVisitor { |
| tcx, |
| } |
| } |
| } |
| |
| impl MutVisitor<'tcx> for EraseRegionsVisitor<'tcx> { |
| fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) { |
| *ty = self.tcx.erase_regions(ty); |
| self.super_ty(ty); |
| } |
| |
| fn visit_region(&mut self, region: &mut ty::Region<'tcx>, _: Location) { |
| *region = self.tcx.lifetimes.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 SubstsRef<'tcx>, _: Location) { |
| *substs = self.tcx.erase_regions(substs); |
| } |
| |
| fn visit_statement(&mut self, |
| statement: &mut Statement<'tcx>, |
| location: Location) { |
| self.super_statement(statement, location); |
| } |
| } |
| |
| pub struct EraseRegions; |
| |
| impl<'tcx> MirPass<'tcx> for EraseRegions { |
| fn run_pass(&self, tcx: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut Body<'tcx>) { |
| EraseRegionsVisitor::new(tcx).visit_body(body); |
| } |
| } |