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Feb 2, 2014
Merged

Substitute type params in default type params using them. #11982

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171 changes: 128 additions & 43 deletions src/librustc/middle/subst.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,18 +13,27 @@
use middle::ty;
use middle::ty_fold;
use middle::ty_fold::TypeFolder;
use util::ppaux::Repr;

use std::rc::Rc;
use syntax::codemap::Span;
use syntax::opt_vec::OptVec;

///////////////////////////////////////////////////////////////////////////
// Public trait `Subst`
//
// Just call `foo.subst(tcx, substs)` to perform a substitution across
// `foo`.
// Or use `foo.subst_spanned(tcx, substs, Some(span))` when there is more
// information available (for better errors).

pub trait Subst {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> Self;
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> Self {
self.subst_spanned(tcx, substs, None)
}
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> Self;
}

///////////////////////////////////////////////////////////////////////////
Expand All @@ -36,19 +45,32 @@ pub trait Subst {
// our current method/trait matching algorithm. - Niko

impl Subst for ty::t {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::t {
if ty::substs_is_noop(substs) {
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> ty::t {
if ty::substs_is_noop(substs) && !ty::type_has_params(*self) {
*self
} else {
let mut folder = SubstFolder {tcx: tcx, substs: substs};
let mut folder = SubstFolder {
tcx: tcx,
substs: substs,
span: span,
root_ty: Some(*self)
};
folder.fold_ty(*self)
}
}
}

struct SubstFolder<'a> {
tcx: ty::ctxt,
substs: &'a ty::substs
substs: &'a ty::substs,

// The location for which the substitution is performed, if available.
span: Option<Span>,

// The root type that is being substituted, if available.
root_ty: Option<ty::t>
}

impl<'a> TypeFolder for SubstFolder<'a> {
Expand All @@ -65,14 +87,42 @@ impl<'a> TypeFolder for SubstFolder<'a> {

match ty::get(t).sty {
ty::ty_param(p) => {
self.substs.tps[p.idx]
if p.idx < self.substs.tps.len() {
self.substs.tps[p.idx]
} else {
let root_msg = match self.root_ty {
Some(root) => format!(" in the substitution of `{}`",
root.repr(self.tcx)),
None => ~""
};
let m = format!("missing type param `{}`{}",
t.repr(self.tcx), root_msg);
match self.span {
Some(span) => self.tcx.sess.span_err(span, m),
None => self.tcx.sess.err(m)
}
ty::mk_err()
}
}
ty::ty_self(_) => {
self.substs.self_ty.expect("ty_self not found in substs")
}
_ => {
ty_fold::super_fold_ty(self, t)
match self.substs.self_ty {
Some(ty) => ty,
None => {
let root_msg = match self.root_ty {
Some(root) => format!(" in the substitution of `{}`",
root.repr(self.tcx)),
None => ~""
};
let m = format!("missing `Self` type param{}", root_msg);
match self.span {
Some(span) => self.tcx.sess.span_err(span, m),
None => self.tcx.sess.err(m)
}
ty::mk_err()
}
}
}
_ => ty_fold::super_fold_ty(self, t)
}
}
}
Expand All @@ -81,112 +131,145 @@ impl<'a> TypeFolder for SubstFolder<'a> {
// Other types

impl<T:Subst> Subst for ~[T] {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ~[T] {
self.map(|t| t.subst(tcx, substs))
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> ~[T] {
self.map(|t| t.subst_spanned(tcx, substs, span))
}
}
impl<T:Subst> Subst for Rc<T> {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> Rc<T> {
Rc::new(self.borrow().subst(tcx, substs))
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> Rc<T> {
Rc::new(self.borrow().subst_spanned(tcx, substs, span))
}
}

impl<T:Subst> Subst for OptVec<T> {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> OptVec<T> {
self.map(|t| t.subst(tcx, substs))
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> OptVec<T> {
self.map(|t| t.subst_spanned(tcx, substs, span))
}
}

impl<T:Subst + 'static> Subst for @T {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> @T {
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> @T {
match self {
t => @(**t).subst(tcx, substs)
t => @(**t).subst_spanned(tcx, substs, span)
}
}
}

impl<T:Subst> Subst for Option<T> {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> Option<T> {
self.as_ref().map(|t| t.subst(tcx, substs))
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> Option<T> {
self.as_ref().map(|t| t.subst_spanned(tcx, substs, span))
}
}

impl Subst for ty::TraitRef {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::TraitRef {
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> ty::TraitRef {
ty::TraitRef {
def_id: self.def_id,
substs: self.substs.subst(tcx, substs)
substs: self.substs.subst_spanned(tcx, substs, span)
}
}
}

impl Subst for ty::substs {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::substs {
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> ty::substs {
ty::substs {
regions: self.regions.subst(tcx, substs),
self_ty: self.self_ty.map(|typ| typ.subst(tcx, substs)),
tps: self.tps.map(|typ| typ.subst(tcx, substs))
regions: self.regions.subst_spanned(tcx, substs, span),
self_ty: self.self_ty.map(|typ| typ.subst_spanned(tcx, substs, span)),
tps: self.tps.map(|typ| typ.subst_spanned(tcx, substs, span))
}
}
}

impl Subst for ty::RegionSubsts {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::RegionSubsts {
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> ty::RegionSubsts {
match *self {
ty::ErasedRegions => {
ty::ErasedRegions
}
ty::NonerasedRegions(ref regions) => {
ty::NonerasedRegions(regions.subst(tcx, substs))
ty::NonerasedRegions(regions.subst_spanned(tcx, substs, span))
}
}
}
}

impl Subst for ty::BareFnTy {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::BareFnTy {
let mut folder = SubstFolder {tcx: tcx, substs: substs};
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> ty::BareFnTy {
let mut folder = SubstFolder {
tcx: tcx,
substs: substs,
span: span,
root_ty: None
};
folder.fold_bare_fn_ty(self)
}
}

impl Subst for ty::ParamBounds {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::ParamBounds {
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> ty::ParamBounds {
ty::ParamBounds {
builtin_bounds: self.builtin_bounds,
trait_bounds: self.trait_bounds.subst(tcx, substs)
trait_bounds: self.trait_bounds.subst_spanned(tcx, substs, span)
}
}
}

impl Subst for ty::TypeParameterDef {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::TypeParameterDef {
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> ty::TypeParameterDef {
ty::TypeParameterDef {
ident: self.ident,
def_id: self.def_id,
bounds: self.bounds.subst(tcx, substs),
default: self.default.map(|x| x.subst(tcx, substs))
bounds: self.bounds.subst_spanned(tcx, substs, span),
default: self.default.map(|x| x.subst_spanned(tcx, substs, span))
}
}
}

impl Subst for ty::Generics {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::Generics {
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> ty::Generics {
ty::Generics {
type_param_defs: self.type_param_defs.subst(tcx, substs),
region_param_defs: self.region_param_defs.subst(tcx, substs),
type_param_defs: self.type_param_defs.subst_spanned(tcx, substs, span),
region_param_defs: self.region_param_defs.subst_spanned(tcx, substs, span),
}
}
}

impl Subst for ty::RegionParameterDef {
fn subst(&self, _: ty::ctxt, _: &ty::substs) -> ty::RegionParameterDef {
fn subst_spanned(&self, _: ty::ctxt,
_: &ty::substs,
_: Option<Span>) -> ty::RegionParameterDef {
*self
}
}

impl Subst for ty::Region {
fn subst(&self, _tcx: ty::ctxt, substs: &ty::substs) -> ty::Region {
fn subst_spanned(&self, _tcx: ty::ctxt,
substs: &ty::substs,
_: Option<Span>) -> ty::Region {
// Note: This routine only handles regions that are bound on
// type declarationss and other outer declarations, not those
// bound in *fn types*. Region substitution of the bound
Expand All @@ -206,10 +289,12 @@ impl Subst for ty::Region {
}

impl Subst for ty::ty_param_bounds_and_ty {
fn subst(&self, tcx: ty::ctxt, substs: &ty::substs) -> ty::ty_param_bounds_and_ty {
fn subst_spanned(&self, tcx: ty::ctxt,
substs: &ty::substs,
span: Option<Span>) -> ty::ty_param_bounds_and_ty {
ty::ty_param_bounds_and_ty {
generics: self.generics.subst(tcx, substs),
ty: self.ty.subst(tcx, substs)
generics: self.generics.subst_spanned(tcx, substs, span),
ty: self.ty.subst_spanned(tcx, substs, span)
}
}
}
16 changes: 12 additions & 4 deletions src/librustc/middle/typeck/astconv.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,7 @@

use middle::const_eval;
use middle::lint;
use middle::subst::Subst;
use middle::ty::{substs};
use middle::ty::{ty_param_substs_and_ty};
use middle::ty;
Expand Down Expand Up @@ -228,16 +229,23 @@ fn ast_path_substs<AC:AstConv,RS:RegionScope>(
~"provided type arguments with defaults");
}

let defaults = decl_generics.type_param_defs().slice_from(supplied_ty_param_count)
.iter().map(|&x| x.default.unwrap());
let tps = path.segments.iter().flat_map(|s| s.types.iter())
.map(|&a_t| ast_ty_to_ty(this, rscope, a_t))
.chain(defaults).collect();
substs {
.collect();

let mut substs = substs {
regions: ty::NonerasedRegions(regions),
self_ty: self_ty,
tps: tps
};

for param in decl_generics.type_param_defs()
.slice_from(supplied_ty_param_count).iter() {
let ty = param.default.unwrap().subst_spanned(tcx, &substs, Some(path.span));
substs.tps.push(ty);
}

substs
}

pub fn ast_path_to_substs_and_ty<AC:AstConv,
Expand Down
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