Fix DeBruijn accounting. It used to be that all trait-refs were binders,
but now only poly-trait-refs are binders. Fixes #20831.
This commit is contained in:
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e94a9f033e
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02aacaba8f
3 changed files with 119 additions and 29 deletions
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@ -516,8 +516,15 @@ pub fn instantiate_poly_trait_ref<'tcx>(
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{
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let mut projections = Vec::new();
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// the trait reference introduces a binding level here, so
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// we need to shift the `rscope`. It'd be nice if we could
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// do away with this rscope stuff and work this knowledge
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// into resolve_lifetimes, as we do with non-omitted
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// lifetimes. Oh well, not there yet.
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let shifted_rscope = ShiftedRscope::new(rscope);
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let trait_ref =
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instantiate_trait_ref(this, rscope, &ast_trait_ref.trait_ref,
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instantiate_trait_ref(this, &shifted_rscope, &ast_trait_ref.trait_ref,
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self_ty, Some(&mut projections));
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for projection in projections.into_iter() {
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@ -561,6 +568,29 @@ pub fn instantiate_trait_ref<'tcx>(
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}
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}
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fn object_path_to_poly_trait_ref<'a,'tcx>(
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this: &AstConv<'tcx>,
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rscope: &RegionScope,
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trait_def_id: ast::DefId,
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path: &ast::Path,
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mut projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
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-> ty::PolyTraitRef<'tcx>
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{
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// we are introducing a binder here, so shift the
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// anonymous regions depth to account for that
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let shifted_rscope = ShiftedRscope::new(rscope);
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let mut tmp = Vec::new();
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let trait_ref = ty::Binder(ast_path_to_trait_ref(this,
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&shifted_rscope,
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trait_def_id,
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None,
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path,
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Some(&mut tmp)));
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projections.extend(tmp.into_iter().map(ty::Binder));
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trait_ref
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}
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fn ast_path_to_trait_ref<'a,'tcx>(
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this: &AstConv<'tcx>,
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rscope: &RegionScope,
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@ -573,13 +603,6 @@ fn ast_path_to_trait_ref<'a,'tcx>(
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debug!("ast_path_to_trait_ref {:?}", path);
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let trait_def = this.get_trait_def(trait_def_id);
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// the trait reference introduces a binding level here, so
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// we need to shift the `rscope`. It'd be nice if we could
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// do away with this rscope stuff and work this knowledge
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// into resolve_lifetimes, as we do with non-omitted
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// lifetimes. Oh well, not there yet.
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let shifted_rscope = ShiftedRscope::new(rscope);
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let (regions, types, assoc_bindings) = match path.segments.last().unwrap().parameters {
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ast::AngleBracketedParameters(ref data) => {
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// For now, require that parenthetical notation be used
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@ -595,7 +618,7 @@ fn ast_path_to_trait_ref<'a,'tcx>(
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the crate attributes to enable");
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}
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convert_angle_bracketed_parameters(this, &shifted_rscope, data)
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convert_angle_bracketed_parameters(this, rscope, data)
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}
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ast::ParenthesizedParameters(ref data) => {
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// For now, require that parenthetical notation be used
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@ -616,7 +639,7 @@ fn ast_path_to_trait_ref<'a,'tcx>(
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};
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let substs = create_substs_for_ast_path(this,
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&shifted_rscope,
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rscope,
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path.span,
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&trait_def.generics,
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self_ty,
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@ -851,15 +874,11 @@ fn ast_ty_to_trait_ref<'tcx>(this: &AstConv<'tcx>,
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match this.tcx().def_map.borrow().get(&id) {
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Some(&def::DefTrait(trait_def_id)) => {
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let mut projection_bounds = Vec::new();
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let trait_ref = ty::Binder(ast_path_to_trait_ref(this,
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rscope,
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trait_def_id,
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None,
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path,
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Some(&mut projection_bounds)));
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let projection_bounds = projection_bounds.into_iter()
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.map(ty::Binder)
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.collect();
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let trait_ref = object_path_to_poly_trait_ref(this,
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rscope,
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trait_def_id,
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path,
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&mut projection_bounds);
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Ok((trait_ref, projection_bounds))
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}
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_ => {
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@ -1095,16 +1114,13 @@ pub fn ast_ty_to_ty<'tcx>(
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// N.B. this case overlaps somewhat with
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// TyObjectSum, see that fn for details
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let mut projection_bounds = Vec::new();
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let trait_ref = ast_path_to_trait_ref(this,
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rscope,
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trait_def_id,
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None,
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path,
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Some(&mut projection_bounds));
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let trait_ref = ty::Binder(trait_ref);
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let projection_bounds = projection_bounds.into_iter()
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.map(ty::Binder)
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.collect();
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let trait_ref = object_path_to_poly_trait_ref(this,
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rscope,
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trait_def_id,
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path,
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&mut projection_bounds);
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trait_ref_to_object_type(this, rscope, path.span,
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trait_ref, projection_bounds, &[])
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}
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49
src/test/compile-fail/issue-20831-debruijn.rs
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49
src/test/compile-fail/issue-20831-debruijn.rs
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@ -0,0 +1,49 @@
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// Copyright 2015 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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// Regression test for #20831: debruijn index account was thrown off
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// by the (anonymous) lifetime in `<Self as Publisher>::Output`
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// below. Note that changing to a named lifetime made the problem go
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// away.
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use std::ops::{Shl, Shr};
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use std::cell::RefCell;
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pub trait Subscriber {
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type Input;
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}
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pub trait Publisher<'a> {
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type Output;
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fn subscribe(&mut self, Box<Subscriber<Input=Self::Output> + 'a>);
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}
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pub trait Processor<'a> : Subscriber + Publisher<'a> { }
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impl<'a, P> Processor<'a> for P where P : Subscriber + Publisher<'a> { }
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struct MyStruct<'a> {
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sub: Box<Subscriber<Input=u64> + 'a>
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}
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impl<'a> Publisher<'a> for MyStruct<'a> {
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type Output = u64;
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fn subscribe(&mut self, t : Box<Subscriber<Input=<Self as Publisher>::Output> + 'a>) {
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// Not obvious, but there is an implicit lifetime here -------^
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//~^^ ERROR cannot infer
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//
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// The fact that `Publisher` is using an implicit lifetime is
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// what was causing the debruijn accounting to be off, so
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// leave it that way!
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self.sub = t;
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}
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}
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fn main() {}
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25
src/test/run-pass/regions-debruijn-of-object.rs
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25
src/test/run-pass/regions-debruijn-of-object.rs
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@ -0,0 +1,25 @@
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// Copyright 2015 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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struct ctxt<'tcx> {
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x: &'tcx i32
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}
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trait AstConv<'tcx> {
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fn tcx<'a>(&'a self) -> &'a ctxt<'tcx>;
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}
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fn foo(conv: &AstConv) { }
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fn bar<'tcx>(conv: &AstConv<'tcx>) {
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foo(conv)
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}
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fn main() { }
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