250 lines
9.0 KiB
Rust
250 lines
9.0 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use abi::Abi;
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use common::*;
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use glue;
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use rustc::hir::def_id::DefId;
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use rustc::middle::lang_items::DropInPlaceFnLangItem;
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use rustc::traits;
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use rustc::ty::adjustment::CustomCoerceUnsized;
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use rustc::ty::subst::{Kind, Subst, Substs};
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use rustc::ty::{self, Ty, TyCtxt};
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use syntax::codemap::DUMMY_SP;
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pub use rustc::ty::Instance;
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fn fn_once_adapter_instance<'a, 'tcx>(
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tcx: TyCtxt<'a, 'tcx, 'tcx>,
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closure_did: DefId,
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substs: ty::ClosureSubsts<'tcx>,
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) -> Instance<'tcx> {
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debug!("fn_once_adapter_shim({:?}, {:?})",
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closure_did,
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substs);
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let fn_once = tcx.lang_items.fn_once_trait().unwrap();
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let call_once = tcx.associated_items(fn_once)
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.find(|it| it.kind == ty::AssociatedKind::Method)
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.unwrap().def_id;
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let def = ty::InstanceDef::ClosureOnceShim { call_once };
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let self_ty = tcx.mk_closure_from_closure_substs(
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closure_did, substs);
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let sig = tcx.fn_sig(closure_did).subst(tcx, substs.substs);
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let sig = tcx.erase_late_bound_regions_and_normalize(&sig);
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assert_eq!(sig.inputs().len(), 1);
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let substs = tcx.mk_substs([
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Kind::from(self_ty),
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Kind::from(sig.inputs()[0]),
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].iter().cloned());
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debug!("fn_once_adapter_shim: self_ty={:?} sig={:?}", self_ty, sig);
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Instance { def, substs }
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}
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fn needs_fn_once_adapter_shim(actual_closure_kind: ty::ClosureKind,
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trait_closure_kind: ty::ClosureKind)
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-> Result<bool, ()>
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{
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match (actual_closure_kind, trait_closure_kind) {
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(ty::ClosureKind::Fn, ty::ClosureKind::Fn) |
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(ty::ClosureKind::FnMut, ty::ClosureKind::FnMut) |
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(ty::ClosureKind::FnOnce, ty::ClosureKind::FnOnce) => {
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// No adapter needed.
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Ok(false)
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}
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(ty::ClosureKind::Fn, ty::ClosureKind::FnMut) => {
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// The closure fn `llfn` is a `fn(&self, ...)`. We want a
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// `fn(&mut self, ...)`. In fact, at trans time, these are
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// basically the same thing, so we can just return llfn.
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Ok(false)
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}
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(ty::ClosureKind::Fn, ty::ClosureKind::FnOnce) |
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(ty::ClosureKind::FnMut, ty::ClosureKind::FnOnce) => {
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// The closure fn `llfn` is a `fn(&self, ...)` or `fn(&mut
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// self, ...)`. We want a `fn(self, ...)`. We can produce
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// this by doing something like:
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//
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// fn call_once(self, ...) { call_mut(&self, ...) }
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// fn call_once(mut self, ...) { call_mut(&mut self, ...) }
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//
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// These are both the same at trans time.
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Ok(true)
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}
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_ => Err(()),
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}
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}
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pub fn resolve_closure<'a, 'tcx> (
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scx: &SharedCrateContext<'a, 'tcx>,
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def_id: DefId,
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substs: ty::ClosureSubsts<'tcx>,
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requested_kind: ty::ClosureKind)
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-> Instance<'tcx>
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{
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let actual_kind = scx.tcx().closure_kind(def_id);
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match needs_fn_once_adapter_shim(actual_kind, requested_kind) {
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Ok(true) => fn_once_adapter_instance(scx.tcx(), def_id, substs),
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_ => Instance::new(def_id, substs.substs)
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}
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}
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fn resolve_associated_item<'a, 'tcx>(
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scx: &SharedCrateContext<'a, 'tcx>,
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trait_item: &ty::AssociatedItem,
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trait_id: DefId,
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rcvr_substs: &'tcx Substs<'tcx>
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) -> Instance<'tcx> {
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let tcx = scx.tcx();
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let def_id = trait_item.def_id;
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debug!("resolve_associated_item(trait_item={:?}, \
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trait_id={:?}, \
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rcvr_substs={:?})",
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def_id, trait_id, rcvr_substs);
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let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_substs);
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let vtbl = tcx.trans_fulfill_obligation(DUMMY_SP, ty::Binder(trait_ref));
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// Now that we know which impl is being used, we can dispatch to
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// the actual function:
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match vtbl {
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traits::VtableImpl(impl_data) => {
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let (def_id, substs) = traits::find_associated_item(
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tcx, trait_item, rcvr_substs, &impl_data);
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let substs = tcx.erase_regions(&substs);
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ty::Instance::new(def_id, substs)
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}
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traits::VtableGenerator(closure_data) => {
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Instance {
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def: ty::InstanceDef::Item(closure_data.closure_def_id),
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substs: closure_data.substs.substs
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}
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}
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traits::VtableClosure(closure_data) => {
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let trait_closure_kind = tcx.lang_items.fn_trait_kind(trait_id).unwrap();
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resolve_closure(scx, closure_data.closure_def_id, closure_data.substs,
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trait_closure_kind)
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}
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traits::VtableFnPointer(ref data) => {
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Instance {
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def: ty::InstanceDef::FnPtrShim(trait_item.def_id, data.fn_ty),
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substs: rcvr_substs
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}
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}
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traits::VtableObject(ref data) => {
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let index = tcx.get_vtable_index_of_object_method(data, def_id);
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Instance {
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def: ty::InstanceDef::Virtual(def_id, index),
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substs: rcvr_substs
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}
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}
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traits::VtableBuiltin(..) if Some(trait_id) == tcx.lang_items.clone_trait() => {
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Instance {
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def: ty::InstanceDef::CloneShim(def_id, trait_ref.self_ty()),
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substs: rcvr_substs
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}
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}
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_ => {
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bug!("static call to invalid vtable: {:?}", vtbl)
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}
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}
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}
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/// The point where linking happens. Resolve a (def_id, substs)
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/// pair to an instance.
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pub fn resolve<'a, 'tcx>(
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scx: &SharedCrateContext<'a, 'tcx>,
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def_id: DefId,
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substs: &'tcx Substs<'tcx>
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) -> Instance<'tcx> {
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debug!("resolve(def_id={:?}, substs={:?})",
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def_id, substs);
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let result = if let Some(trait_def_id) = scx.tcx().trait_of_item(def_id) {
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debug!(" => associated item, attempting to find impl");
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let item = scx.tcx().associated_item(def_id);
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resolve_associated_item(scx, &item, trait_def_id, substs)
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} else {
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let item_type = def_ty(scx, def_id, substs);
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let def = match item_type.sty {
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ty::TyFnDef(..) if {
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let f = item_type.fn_sig(scx.tcx());
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f.abi() == Abi::RustIntrinsic ||
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f.abi() == Abi::PlatformIntrinsic
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} =>
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{
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debug!(" => intrinsic");
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ty::InstanceDef::Intrinsic(def_id)
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}
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_ => {
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if Some(def_id) == scx.tcx().lang_items.drop_in_place_fn() {
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let ty = substs.type_at(0);
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if glue::needs_drop_glue(scx, ty) {
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debug!(" => nontrivial drop glue");
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ty::InstanceDef::DropGlue(def_id, Some(ty))
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} else {
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debug!(" => trivial drop glue");
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ty::InstanceDef::DropGlue(def_id, None)
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}
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} else {
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debug!(" => free item");
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ty::InstanceDef::Item(def_id)
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}
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}
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};
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Instance { def, substs }
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};
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debug!("resolve(def_id={:?}, substs={:?}) = {}",
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def_id, substs, result);
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result
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}
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pub fn resolve_drop_in_place<'a, 'tcx>(
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scx: &SharedCrateContext<'a, 'tcx>,
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ty: Ty<'tcx>)
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-> ty::Instance<'tcx>
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{
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let def_id = scx.tcx().require_lang_item(DropInPlaceFnLangItem);
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let substs = scx.tcx().intern_substs(&[Kind::from(ty)]);
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resolve(scx, def_id, substs)
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}
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pub fn custom_coerce_unsize_info<'scx, 'tcx>(scx: &SharedCrateContext<'scx, 'tcx>,
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source_ty: Ty<'tcx>,
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target_ty: Ty<'tcx>)
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-> CustomCoerceUnsized {
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let trait_ref = ty::Binder(ty::TraitRef {
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def_id: scx.tcx().lang_items.coerce_unsized_trait().unwrap(),
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substs: scx.tcx().mk_substs_trait(source_ty, &[target_ty])
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});
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match scx.tcx().trans_fulfill_obligation(DUMMY_SP, trait_ref) {
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traits::VtableImpl(traits::VtableImplData { impl_def_id, .. }) => {
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scx.tcx().coerce_unsized_info(impl_def_id).custom_kind.unwrap()
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}
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vtable => {
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bug!("invalid CoerceUnsized vtable: {:?}", vtable);
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}
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}
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}
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/// Returns the normalized type of a struct field
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pub fn field_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
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param_substs: &Substs<'tcx>,
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f: &'tcx ty::FieldDef)
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-> Ty<'tcx>
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{
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tcx.normalize_associated_type(&f.ty(tcx, param_substs))
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}
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