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Accept quantification of lifetimes outside the self type in where clauses.

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Closes #20022
This commit is contained in:
Nick Cameron 2015-02-05 21:46:01 +13:00
parent 012e9643e4
commit 8122ce81d0
10 changed files with 100 additions and 27 deletions
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3
src/librustc/diagnostics.rs
View File

@ -126,7 +126,8 @@ register_diagnostics! {
E0312, // lifetime of reference outlives lifetime of borrowed content
E0313, // lifetime of borrowed pointer outlives lifetime of captured variable
E0314, // closure outlives stack frame
E0315 // cannot invoke closure outside of its lifetime
E0315, // cannot invoke closure outside of its lifetime
E0316 // nested quantification of lifetimes
}
__build_diagnostic_array! { DIAGNOSTICS }

3
src/librustc/middle/infer/error_reporting.rs
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@ -1076,7 +1076,8 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
trait_ref: ast::TraitRef {
path: new_path,
ref_id: tr.ref_id,
}
},
span: poly_tr.span,
}, modifier)
}
}

64
src/librustc/middle/resolve_lifetime.rs
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@ -45,8 +45,8 @@ pub enum DefRegion {
/* lifetime decl */ ast::NodeId),
}
// maps the id of each lifetime reference to the lifetime decl
// that it corresponds to
// Maps the id of each lifetime reference to the lifetime decl
// that it corresponds to.
pub type NamedRegionMap = NodeMap<DefRegion>;
struct LifetimeContext<'a> {
@ -54,6 +54,22 @@ struct LifetimeContext<'a> {
named_region_map: &'a mut NamedRegionMap,
scope: Scope<'a>,
def_map: &'a DefMap,
// Deep breath. Our representation for poly trait refs contains a single
// binder and thus we only allow a single level of quantification. However,
// the syntax of Rust permits quantification in two places, e.g., `T: for <'a> Foo<'a>`
// and `for <'a, 'b> &'b T: Foo<'a>`. In order to get the de Bruijn indices
// correct when representing these constraints, we should only introduce one
// scope. However, we want to support both locations for the quantifier and
// during lifetime resolution we want precise information (so we can't
// desugar in an earlier phase).
// SO, if we encounter a quantifier at the outer scope, we set
// trait_ref_hack to true (and introduce a scope), and then if we encounter
// a quantifier at the inner scope, we error. If trait_ref_hack is false,
// then we introduce the scope at the inner quantifier.
// I'm sorry.
trait_ref_hack: bool,
}
enum ScopeChain<'a> {
@ -80,6 +96,7 @@ pub fn krate(sess: &Session, krate: &ast::Crate, def_map: &DefMap) -> NamedRegio
named_region_map: &mut named_region_map,
scope: &ROOT_SCOPE,
def_map: def_map,
trait_ref_hack: false,
}, krate);
sess.abort_if_errors();
named_region_map
@ -198,9 +215,22 @@ impl<'a, 'v> Visitor<'v> for LifetimeContext<'a> {
match predicate {
&ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{ ref bounded_ty,
ref bounds,
ref bound_lifetimes,
.. }) => {
self.visit_ty(&**bounded_ty);
visit::walk_ty_param_bounds_helper(self, bounds);
if bound_lifetimes.len() > 0 {
self.trait_ref_hack = true;
let result = self.with(LateScope(bound_lifetimes, self.scope),
|old_scope, this| {
this.check_lifetime_defs(old_scope, bound_lifetimes);
this.visit_ty(&**bounded_ty);
visit::walk_ty_param_bounds_helper(this, bounds);
});
self.trait_ref_hack = false;
result
} else {
self.visit_ty(&**bounded_ty);
visit::walk_ty_param_bounds_helper(self, bounds);
}
}
&ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate{ref lifetime,
ref bounds,
@ -222,18 +252,27 @@ impl<'a, 'v> Visitor<'v> for LifetimeContext<'a> {
}
}
fn visit_poly_trait_ref(&mut self, trait_ref:
&ast::PolyTraitRef,
fn visit_poly_trait_ref(&mut self,
trait_ref: &ast::PolyTraitRef,
_modifier: &ast::TraitBoundModifier) {
debug!("visit_poly_trait_ref trait_ref={:?}", trait_ref);
self.with(LateScope(&trait_ref.bound_lifetimes, self.scope), |old_scope, this| {
this.check_lifetime_defs(old_scope, &trait_ref.bound_lifetimes);
for lifetime in &trait_ref.bound_lifetimes {
this.visit_lifetime_def(lifetime);
if !self.trait_ref_hack || trait_ref.bound_lifetimes.len() > 0 {
if self.trait_ref_hack {
println!("{:?}", trait_ref.span);
span_err!(self.sess, trait_ref.span, E0316,
"nested quantification of lifetimes");
}
this.visit_trait_ref(&trait_ref.trait_ref)
})
self.with(LateScope(&trait_ref.bound_lifetimes, self.scope), |old_scope, this| {
this.check_lifetime_defs(old_scope, &trait_ref.bound_lifetimes);
for lifetime in &trait_ref.bound_lifetimes {
this.visit_lifetime_def(lifetime);
}
this.visit_trait_ref(&trait_ref.trait_ref)
})
} else {
self.visit_trait_ref(&trait_ref.trait_ref)
}
}
fn visit_trait_ref(&mut self, trait_ref: &ast::TraitRef) {
@ -251,6 +290,7 @@ impl<'a> LifetimeContext<'a> {
named_region_map: *named_region_map,
scope: &wrap_scope,
def_map: self.def_map,
trait_ref_hack: self.trait_ref_hack,
};
debug!("entering scope {:?}", this.scope);
f(self.scope, &mut this);

2
src/librustc/middle/ty.rs
View File

@ -1478,7 +1478,7 @@ impl<'tcx> PolyTraitRef<'tcx> {
/// compiler's representation for things like `for<'a> Fn(&'a int)`
/// (which would be represented by the type `PolyTraitRef ==
/// Binder<TraitRef>`). Note that when we skolemize, instantiate,
/// erase, or otherwise "discharge" these bound reons, we change the
/// erase, or otherwise "discharge" these bound regions, we change the
/// type from `Binder<T>` to just `T` (see
/// e.g. `liberate_late_bound_regions`).
#[derive(Clone, PartialEq, Eq, Hash, Debug)]

2
src/librustc_typeck/astconv.rs
View File

@ -526,7 +526,7 @@ pub fn instantiate_poly_trait_ref<'tcx>(
{
let mut projections = Vec::new();
// the trait reference introduces a binding level here, so
// The trait reference introduces a binding level here, so
// we need to shift the `rscope`. It'd be nice if we could
// do away with this rscope stuff and work this knowledge
// into resolve_lifetimes, as we do with non-omitted

3
src/libsyntax/ast.rs
View File

@ -443,6 +443,7 @@ pub enum WherePredicate {
#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
pub struct WhereBoundPredicate {
pub span: Span,
pub bound_lifetimes: Vec<LifetimeDef>,
pub bounded_ty: P<Ty>,
pub bounds: OwnedSlice<TyParamBound>,
}
@ -1535,6 +1536,8 @@ pub struct PolyTraitRef {
/// The `Foo<&'a T>` in `<'a> Foo<&'a T>`
pub trait_ref: TraitRef,
pub span: Span,
}
#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]

9
src/libsyntax/ext/build.rs
View File

@ -70,7 +70,7 @@ pub trait AstBuilder {
default: Option<P<ast::Ty>>) -> ast::TyParam;
fn trait_ref(&self, path: ast::Path) -> ast::TraitRef;
fn poly_trait_ref(&self, path: ast::Path) -> ast::PolyTraitRef;
fn poly_trait_ref(&self, span: Span, path: ast::Path) -> ast::PolyTraitRef;
fn typarambound(&self, path: ast::Path) -> ast::TyParamBound;
fn lifetime(&self, span: Span, ident: ast::Name) -> ast::Lifetime;
fn lifetime_def(&self,
@ -442,15 +442,16 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
}
}
fn poly_trait_ref(&self, path: ast::Path) -> ast::PolyTraitRef {
fn poly_trait_ref(&self, span: Span, path: ast::Path) -> ast::PolyTraitRef {
ast::PolyTraitRef {
bound_lifetimes: Vec::new(),
trait_ref: self.trait_ref(path)
trait_ref: self.trait_ref(path),
span: span,
}
}
fn typarambound(&self, path: ast::Path) -> ast::TyParamBound {
ast::TraitTyParamBound(self.poly_trait_ref(path), ast::TraitBoundModifier::None)
ast::TraitTyParamBound(self.poly_trait_ref(path.span, path), ast::TraitBoundModifier::None)
}
fn lifetime(&self, span: Span, name: ast::Name) -> ast::Lifetime {

1
src/libsyntax/ext/deriving/generic/mod.rs
View File

@ -443,6 +443,7 @@ impl<'a> TraitDef<'a> {
ast::WherePredicate::BoundPredicate(ref wb) => {
ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
span: self.span,
bound_lifetimes: wb.bound_lifetimes.clone(),
bounded_ty: wb.bounded_ty.clone(),
bounds: OwnedSlice::from_vec(wb.bounds.iter().map(|b| b.clone()).collect())
})

7
src/libsyntax/fold.rs
View File

@ -806,10 +806,12 @@ pub fn noop_fold_where_predicate<T: Folder>(
fld: &mut T)
-> WherePredicate {
match pred {
ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{bounded_ty,
ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{bound_lifetimes,
bounded_ty,
bounds,
span}) => {
ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
bound_lifetimes: fld.fold_lifetime_defs(bound_lifetimes),
bounded_ty: fld.fold_ty(bounded_ty),
bounds: bounds.move_map(|x| fld.fold_ty_param_bound(x)),
span: fld.new_span(span)
@ -895,7 +897,8 @@ pub fn noop_fold_trait_ref<T: Folder>(p: TraitRef, fld: &mut T) -> TraitRef {
pub fn noop_fold_poly_trait_ref<T: Folder>(p: PolyTraitRef, fld: &mut T) -> PolyTraitRef {
ast::PolyTraitRef {
bound_lifetimes: fld.fold_lifetime_defs(p.bound_lifetimes),
trait_ref: fld.fold_trait_ref(p.trait_ref)
trait_ref: fld.fold_trait_ref(p.trait_ref),
span: fld.new_span(p.span),
}
}

33
src/libsyntax/parse/parser.rs
View File

@ -1036,6 +1036,8 @@ impl<'a> Parser<'a> {
*/
// parse <'lt>
let lo = self.span.lo;
let lifetime_defs = self.parse_late_bound_lifetime_defs();
// examine next token to decide to do
@ -1047,9 +1049,11 @@ impl<'a> Parser<'a> {
self.token.is_ident() ||
self.token.is_path()
{
let hi = self.span.hi;
let trait_ref = self.parse_trait_ref();
let poly_trait_ref = ast::PolyTraitRef { bound_lifetimes: lifetime_defs,
trait_ref: trait_ref };
trait_ref: trait_ref,
span: mk_sp(lo, hi)};
let other_bounds = if self.eat(&token::BinOp(token::Plus)) {
self.parse_ty_param_bounds(BoundParsingMode::Bare)
} else {
@ -4070,7 +4074,8 @@ impl<'a> Parser<'a> {
if let Some(unbound) = unbound {
let mut bounds_as_vec = bounds.into_vec();
bounds_as_vec.push(TraitTyParamBound(PolyTraitRef { bound_lifetimes: vec![],
trait_ref: unbound },
trait_ref: unbound,
span: span },
TraitBoundModifier::Maybe));
bounds = OwnedSlice::from_vec(bounds_as_vec);
};
@ -4223,6 +4228,16 @@ impl<'a> Parser<'a> {
}
_ => {
let bound_lifetimes = if self.eat_keyword(keywords::For) {
// Higher ranked constraint.
self.expect(&token::Lt);
let lifetime_defs = self.parse_lifetime_defs();
self.expect_gt();
lifetime_defs
} else {
vec![]
};
let bounded_ty = self.parse_ty();
if self.eat(&token::Colon) {
@ -4233,12 +4248,13 @@ impl<'a> Parser<'a> {
if bounds.len() == 0 {
self.span_err(span,
"each predicate in a `where` clause must have \
at least one bound in it");
at least one bound in it");
}
generics.where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
ast::WhereBoundPredicate {
span: span,
bound_lifetimes: bound_lifetimes,
bounded_ty: bounded_ty,
bounds: bounds,
}));
@ -4674,8 +4690,12 @@ impl<'a> Parser<'a> {
/// Parse trait Foo { ... }
fn parse_item_trait(&mut self, unsafety: Unsafety) -> ItemInfo {
let ident = self.parse_ident();
let mut tps = self.parse_generics();
// This is not very accurate, but since unbound only exists to catch
// obsolete syntax, the span is unlikely to ever be used.
let unbound_span = self.span;
let unbound = self.parse_for_sized();
// Parse supertrait bounds.
@ -4684,7 +4704,8 @@ impl<'a> Parser<'a> {
if let Some(unbound) = unbound {
let mut bounds_as_vec = bounds.into_vec();
bounds_as_vec.push(TraitTyParamBound(PolyTraitRef { bound_lifetimes: vec![],
trait_ref: unbound },
trait_ref: unbound,
span: unbound_span },
TraitBoundModifier::Maybe));
bounds = OwnedSlice::from_vec(bounds_as_vec);
};
@ -4803,11 +4824,13 @@ impl<'a> Parser<'a> {
/// Parse for<'l> a::B<String,i32>
fn parse_poly_trait_ref(&mut self) -> PolyTraitRef {
let lo = self.span.lo;
let lifetime_defs = self.parse_late_bound_lifetime_defs();
ast::PolyTraitRef {
bound_lifetimes: lifetime_defs,
trait_ref: self.parse_trait_ref()
trait_ref: self.parse_trait_ref(),
span: mk_sp(lo, self.last_span.hi),
}
}