diff options
Diffstat (limited to 'src/librustc/middle/infer/combine.rs')
| -rw-r--r-- | src/librustc/middle/infer/combine.rs | 146 |
1 files changed, 76 insertions, 70 deletions
diff --git a/src/librustc/middle/infer/combine.rs b/src/librustc/middle/infer/combine.rs index daa820f43b5..0eeafb767d8 100644 --- a/src/librustc/middle/infer/combine.rs +++ b/src/librustc/middle/infer/combine.rs @@ -32,6 +32,7 @@ // is also useful to track which value is the "expected" value in // terms of error reporting. +use super::bivariate::Bivariate; use super::equate::Equate; use super::glb::Glb; use super::lub::Lub; @@ -39,7 +40,7 @@ use super::sub::Sub; use super::unify::InferCtxtMethodsForSimplyUnifiableTypes; use super::{InferCtxt, cres}; use super::{MiscVariable, TypeTrace}; -use super::type_variable::{RelationDir, EqTo, SubtypeOf, SupertypeOf}; +use super::type_variable::{RelationDir, BiTo, EqTo, SubtypeOf, SupertypeOf}; use middle::subst; use middle::subst::{ErasedRegions, NonerasedRegions, Substs}; @@ -48,7 +49,7 @@ use middle::ty::{IntType, UintType}; use middle::ty::{BuiltinBounds}; use middle::ty::{self, Ty}; use middle::ty_fold; -use middle::ty_fold::{TypeFoldable}; +use middle::ty_fold::{TypeFolder, TypeFoldable}; use util::ppaux::Repr; use std::rc::Rc; @@ -58,41 +59,32 @@ use syntax::abi; use syntax::codemap::Span; pub trait Combine<'tcx> : Sized { - fn infcx<'a>(&'a self) -> &'a InferCtxt<'a, 'tcx>; fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx> { self.infcx().tcx } fn tag(&self) -> String; - fn a_is_expected(&self) -> bool; - fn trace(&self) -> TypeTrace<'tcx>; - fn equate<'a>(&'a self) -> Equate<'a, 'tcx>; - fn sub<'a>(&'a self) -> Sub<'a, 'tcx>; - fn lub<'a>(&'a self) -> Lub<'a, 'tcx>; - fn glb<'a>(&'a self) -> Glb<'a, 'tcx>; + fn fields<'a>(&'a self) -> &'a CombineFields<'a, 'tcx>; + + fn infcx<'a>(&'a self) -> &'a InferCtxt<'a, 'tcx> { self.fields().infcx } + fn a_is_expected(&self) -> bool { self.fields().a_is_expected } + fn trace(&self) -> TypeTrace<'tcx> { self.fields().trace.clone() } + fn equate<'a>(&'a self) -> Equate<'a, 'tcx> { self.fields().equate() } + fn bivariate<'a>(&'a self) -> Bivariate<'a, 'tcx> { self.fields().bivariate() } + + fn sub<'a>(&'a self) -> Sub<'a, 'tcx> { self.fields().sub() } + fn lub<'a>(&'a self) -> Lub<'a, 'tcx> { Lub(self.fields().clone()) } + fn glb<'a>(&'a self) -> Glb<'a, 'tcx> { Glb(self.fields().clone()) } fn mts(&self, a: &ty::mt<'tcx>, b: &ty::mt<'tcx>) -> cres<'tcx, ty::mt<'tcx>>; - fn contratys(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> cres<'tcx, Ty<'tcx>>; + + fn tys_with_variance(&self, variance: ty::Variance, a: Ty<'tcx>, b: Ty<'tcx>) + -> cres<'tcx, Ty<'tcx>>; + fn tys(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> cres<'tcx, Ty<'tcx>>; - fn tps(&self, - _: subst::ParamSpace, - as_: &[Ty<'tcx>], - bs: &[Ty<'tcx>]) - -> cres<'tcx, Vec<Ty<'tcx>>> { - // FIXME -- In general, we treat variance a bit wrong - // here. For historical reasons, we treat tps and Self - // as invariant. This is overly conservative. - - if as_.len() != bs.len() { - return Err(ty::terr_ty_param_size(expected_found(self, - as_.len(), - bs.len()))); - } + fn regions_with_variance(&self, variance: ty::Variance, a: ty::Region, b: ty::Region) + -> cres<'tcx, ty::Region>; - try!(as_.iter().zip(bs.iter()) - .map(|(a, b)| self.equate().tys(*a, *b)) - .collect::<cres<Vec<Ty>>>()); - Ok(as_.to_vec()) - } + fn regions(&self, a: ty::Region, b: ty::Region) -> cres<'tcx, ty::Region>; fn substs(&self, item_def_id: ast::DefId, @@ -100,6 +92,11 @@ pub trait Combine<'tcx> : Sized { b_subst: &subst::Substs<'tcx>) -> cres<'tcx, subst::Substs<'tcx>> { + debug!("substs: item_def_id={} a_subst={} b_subst={}", + item_def_id.repr(self.infcx().tcx), + a_subst.repr(self.infcx().tcx), + b_subst.repr(self.infcx().tcx)); + let variances = if self.infcx().tcx.variance_computed.get() { Some(ty::item_variances(self.infcx().tcx, item_def_id)) } else { @@ -119,7 +116,8 @@ pub trait Combine<'tcx> : Sized { for &space in &subst::ParamSpace::all() { let a_tps = a_subst.types.get_slice(space); let b_tps = b_subst.types.get_slice(space); - let tps = try!(self.tps(space, a_tps, b_tps)); + let t_variances = variances.map(|v| v.types.get_slice(space)); + let tps = try!(relate_type_params(self, t_variances, a_tps, b_tps)); substs.types.replace(space, tps); } @@ -132,20 +130,7 @@ pub trait Combine<'tcx> : Sized { for &space in &subst::ParamSpace::all() { let a_regions = a.get_slice(space); let b_regions = b.get_slice(space); - - let mut invariance = Vec::new(); - let r_variances = match variances { - Some(variances) => { - variances.regions.get_slice(space) - } - None => { - for _ in a_regions { - invariance.push(ty::Invariant); - } - &invariance[] - } - }; - + let r_variances = variances.map(|v| v.regions.get_slice(space)); let regions = try!(relate_region_params(self, r_variances, a_regions, @@ -157,13 +142,34 @@ pub trait Combine<'tcx> : Sized { return Ok(substs); + fn relate_type_params<'tcx, C: Combine<'tcx>>(this: &C, + variances: Option<&[ty::Variance]>, + a_tys: &[Ty<'tcx>], + b_tys: &[Ty<'tcx>]) + -> cres<'tcx, Vec<Ty<'tcx>>> + { + if a_tys.len() != b_tys.len() { + return Err(ty::terr_ty_param_size(expected_found(this, + a_tys.len(), + b_tys.len()))); + } + + range(0, a_tys.len()).map(|i| { + let a_ty = a_tys[i]; + let b_ty = b_tys[i]; + let v = variances.map_or(ty::Invariant, |v| v[i]); + this.tys_with_variance(v, a_ty, b_ty) + }).collect() + } + fn relate_region_params<'tcx, C: Combine<'tcx>>(this: &C, - variances: &[ty::Variance], + variances: Option<&[ty::Variance]>, a_rs: &[ty::Region], b_rs: &[ty::Region]) - -> cres<'tcx, Vec<ty::Region>> { + -> cres<'tcx, Vec<ty::Region>> + { let tcx = this.infcx().tcx; - let num_region_params = variances.len(); + let num_region_params = a_rs.len(); debug!("relate_region_params(\ a_rs={}, \ @@ -173,22 +179,18 @@ pub trait Combine<'tcx> : Sized { b_rs.repr(tcx), variances.repr(tcx)); - assert_eq!(num_region_params, a_rs.len()); + assert_eq!(num_region_params, + variances.map_or(num_region_params, + |v| v.len())); + assert_eq!(num_region_params, b_rs.len()); - let mut rs = vec!(); - for i in 0..num_region_params { + + (0..a_rs.len()).map(|i| { let a_r = a_rs[i]; let b_r = b_rs[i]; - let variance = variances[i]; - let r = match variance { - ty::Invariant => this.equate().regions(a_r, b_r), - ty::Covariant => this.regions(a_r, b_r), - ty::Contravariant => this.contraregions(a_r, b_r), - ty::Bivariant => Ok(a_r), - }; - rs.push(try!(r)); - } - Ok(rs) + let variance = variances.map_or(ty::Invariant, |v| v[i]); + this.regions_with_variance(variance, a_r, b_r) + }).collect() } } @@ -241,7 +243,7 @@ pub trait Combine<'tcx> : Sized { } fn args(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> cres<'tcx, Ty<'tcx>> { - self.contratys(a, b).and_then(|t| Ok(t)) + self.tys_with_variance(ty::Contravariant, a, b).and_then(|t| Ok(t)) } fn unsafeties(&self, a: Unsafety, b: Unsafety) -> cres<'tcx, Unsafety>; @@ -309,7 +311,7 @@ pub trait Combine<'tcx> : Sized { b: &ty::ExistentialBounds<'tcx>) -> cres<'tcx, ty::ExistentialBounds<'tcx>> { - let r = try!(self.contraregions(a.region_bound, b.region_bound)); + let r = try!(self.regions_with_variance(ty::Contravariant, a.region_bound, b.region_bound)); let nb = try!(self.builtin_bounds(a.builtin_bounds, b.builtin_bounds)); let pb = try!(self.projection_bounds(&a.projection_bounds, &b.projection_bounds)); Ok(ty::ExistentialBounds { region_bound: r, @@ -322,11 +324,6 @@ pub trait Combine<'tcx> : Sized { b: ty::BuiltinBounds) -> cres<'tcx, ty::BuiltinBounds>; - fn contraregions(&self, a: ty::Region, b: ty::Region) - -> cres<'tcx, ty::Region>; - - fn regions(&self, a: ty::Region, b: ty::Region) -> cres<'tcx, ty::Region>; - fn trait_refs(&self, a: &ty::TraitRef<'tcx>, b: &ty::TraitRef<'tcx>) @@ -540,7 +537,8 @@ pub fn super_tys<'tcx, C: Combine<'tcx>>(this: &C, } (&ty::ty_rptr(a_r, ref a_mt), &ty::ty_rptr(b_r, ref b_mt)) => { - let r = try!(this.contraregions(*a_r, *b_r)); + let r = try!(this.regions_with_variance(ty::Contravariant, *a_r, *b_r)); + // FIXME(14985) If we have mutable references to trait objects, we // used to use covariant subtyping. I have preserved this behaviour, // even though it is probably incorrect. So don't go down the usual @@ -644,6 +642,10 @@ impl<'f, 'tcx> CombineFields<'f, 'tcx> { Equate((*self).clone()) } + fn bivariate(&self) -> Bivariate<'f, 'tcx> { + Bivariate((*self).clone()) + } + fn sub(&self) -> Sub<'f, 'tcx> { Sub((*self).clone()) } @@ -697,7 +699,7 @@ impl<'f, 'tcx> CombineFields<'f, 'tcx> { EqTo => { self.generalize(a_ty, b_vid, false) } - SupertypeOf | SubtypeOf => { + BiTo | SupertypeOf | SubtypeOf => { self.generalize(a_ty, b_vid, true) } }); @@ -721,6 +723,10 @@ impl<'f, 'tcx> CombineFields<'f, 'tcx> { // to associate causes/spans with each of the relations in // the stack to get this right. match dir { + BiTo => { + try!(self.bivariate().tys(a_ty, b_ty)); + } + EqTo => { try!(self.equate().tys(a_ty, b_ty)); } @@ -730,7 +736,7 @@ impl<'f, 'tcx> CombineFields<'f, 'tcx> { } SupertypeOf => { - try!(self.sub().contratys(a_ty, b_ty)); + try!(self.sub().tys_with_variance(ty::Contravariant, a_ty, b_ty)); } } } |