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auto merge of #11982 : eddyb/rust/generic-default-type-params, r=pcwalton

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Fixes #11964 and closes #8998.
This commit is contained in:
bors 2014-02-02 04:16:17 -08:00
commit 3e0eb3c0bf
7 changed files with 245 additions and 80 deletions
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171
src/librustc/middle/subst.rs
View File

@ -13,8 +13,10 @@
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;
///////////////////////////////////////////////////////////////////////////
@ -22,9 +24,16 @@ use syntax::opt_vec::OptVec;
//
// 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;
}
///////////////////////////////////////////////////////////////////////////
@ -36,11 +45,18 @@ 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)
}
}
@ -48,7 +64,13 @@ impl Subst for ty::t {
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> {
@ -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)
}
}
}
@ -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
@ -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
src/librustc/middle/typeck/astconv.rs
View File

@ -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;
@ -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,

74
src/librustc/middle/typeck/check/mod.rs
View File

@ -3744,6 +3744,7 @@ pub fn instantiate_path(fcx: @FnCtxt,
infer::BoundRegionInTypeOrImpl(span),
num_expected_regions))
};
let regions = ty::NonerasedRegions(regions);
// Special case: If there is a self parameter, omit it from the list of
// type parameters.
@ -3762,12 +3763,12 @@ pub fn instantiate_path(fcx: @FnCtxt,
// determine values for type parameters, using the values given by
// the user (if any) and otherwise using fresh type variables
let tps = if ty_substs_len == 0 {
fcx.infcx().next_ty_vars(ty_param_count)
let (tps, regions) = if ty_substs_len == 0 {
(fcx.infcx().next_ty_vars(ty_param_count), regions)
} else if ty_param_count == 0 {
fcx.ccx.tcx.sess.span_err
(span, "this item does not take type parameters");
fcx.infcx().next_ty_vars(ty_param_count)
(fcx.infcx().next_ty_vars(ty_param_count), regions)
} else if ty_substs_len > user_ty_param_count {
let expected = if user_ty_param_req < user_ty_param_count {
"expected at most"
@ -3778,7 +3779,7 @@ pub fn instantiate_path(fcx: @FnCtxt,
(span,
format!("too many type parameters provided: {} {}, found {}",
expected, user_ty_param_count, ty_substs_len));
fcx.infcx().next_ty_vars(ty_param_count)
(fcx.infcx().next_ty_vars(ty_param_count), regions)
} else if ty_substs_len < user_ty_param_req {
let expected = if user_ty_param_req < user_ty_param_count {
"expected at least"
@ -3789,7 +3790,7 @@ pub fn instantiate_path(fcx: @FnCtxt,
(span,
format!("not enough type parameters provided: {} {}, found {}",
expected, user_ty_param_req, ty_substs_len));
fcx.infcx().next_ty_vars(ty_param_count)
(fcx.infcx().next_ty_vars(ty_param_count), regions)
} else {
if ty_substs_len > user_ty_param_req {
fcx.tcx().sess.add_lint(lint::DefaultTypeParamUsage, node_id, pth.span,
@ -3798,50 +3799,71 @@ pub fn instantiate_path(fcx: @FnCtxt,
// Build up the list of type parameters, inserting the self parameter
// at the appropriate position.
let mut result = ~[];
let mut tps = ~[];
let mut pushed = false;
for (i, ty) in pth.segments.iter()
.flat_map(|segment| segment.types.iter())
.map(|&ast_type| fcx.to_ty(ast_type))
.enumerate() {
match self_parameter_index {
Some(index) if index == i => {
tps.push(fcx.infcx().next_ty_vars(1)[0]);
pushed = true;
}
_ => {}
}
tps.push(ty)
}
let mut substs = substs {
regions: regions,
self_ty: None,
tps: tps
};
let defaults = tpt.generics.type_param_defs().iter()
.enumerate().filter_map(|(i, x)| {
match self_parameter_index {
Some(index) if index == i => None,
_ => Some(x.default)
}
}).skip(ty_substs_len).map(|x| match x {
Some(default) => default,
None => {
fcx.tcx().sess.span_bug(span,
"missing default for a not explicitely provided type param")
}
});
for (i, ty) in pth.segments.iter()
.flat_map(|segment| segment.types.iter())
.map(|&ast_type| fcx.to_ty(ast_type))
.chain(defaults).enumerate() {
for (i, default) in defaults.skip(ty_substs_len).enumerate() {
match self_parameter_index {
Some(index) if index == i => {
result.push(fcx.infcx().next_ty_vars(1)[0]);
Some(index) if index == i + ty_substs_len => {
substs.tps.push(fcx.infcx().next_ty_vars(1)[0]);
pushed = true;
}
_ => {}
}
result.push(ty)
match default {
Some(default) => {
let ty = default.subst_spanned(fcx.tcx(), &substs, Some(span));
substs.tps.push(ty);
}
None => {
fcx.tcx().sess.span_bug(span,
"missing default for a not explicitely provided type param")
}
}
}
// If the self parameter goes at the end, insert it there.
if !pushed && self_parameter_index.is_some() {
result.push(fcx.infcx().next_ty_vars(1)[0])
substs.tps.push(fcx.infcx().next_ty_vars(1)[0])
}
assert_eq!(result.len(), ty_param_count)
result
assert_eq!(substs.tps.len(), ty_param_count)
let substs {tps, regions, ..} = substs;
(tps, regions)
};
let substs = substs {
regions: ty::NonerasedRegions(regions),
fcx.write_ty_substs(node_id, tpt.ty, substs {
regions: regions,
self_ty: None,
tps: tps
};
fcx.write_ty_substs(node_id, tpt.ty, substs);
});
debug!("<<<");
}

26
src/librustc/util/ppaux.rs
View File

@ -525,13 +525,25 @@ pub fn parameterized(cx: ctxt,
} else {
ty::lookup_item_type(cx, did).generics
};
let ty_params = generics.type_param_defs().iter();
let num_defaults = ty_params.zip(tps.iter()).rev().take_while(|&(def, &actual)| {
match def.default {
Some(default) => default == actual,
None => false
}
}).len();
let ty_params = generics.type_param_defs();
let has_defaults = ty_params.last().map_or(false, |def| def.default.is_some());
let num_defaults = if has_defaults {
// We should have a borrowed version of substs instead of cloning.
let mut substs = ty::substs {
tps: tps.to_owned(),
regions: regions.clone(),
self_ty: None
};
ty_params.iter().zip(tps.iter()).rev().take_while(|&(def, &actual)| {
substs.tps.pop();
match def.default {
Some(default) => ty::subst(cx, &substs, default) == actual,
None => false
}
}).len()
} else {
0
};
for t in tps.slice_to(tps.len() - num_defaults).iter() {
strs.push(ty_to_str(cx, *t))

19
src/test/compile-fail/generic-type-params-forward-mention.rs Normal file
View File

@ -0,0 +1,19 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[feature(default_type_params)];
// Ensure that we get an error and not an ICE for this problematic case.
struct Foo<T = Option<U>, U = bool>;
fn main() {
let x: Foo;
//~^ ERROR missing type param `U` in the substitution of `std::option::Option<U>`
}

9
src/test/compile-fail/generic-type-params-name-repr.rs
View File

@ -15,6 +15,9 @@ struct B;
struct C;
struct Foo<T = A, U = B, V = C>;
struct Hash<T>;
struct HashMap<K, V, H = Hash<K>>;
fn main() {
// Ensure that the printed type doesn't include the default type params...
let _: Foo<int> = ();
@ -24,6 +27,12 @@ fn main() {
let _: Foo<int, B, C> = ();
//~^ ERROR mismatched types: expected `Foo<int>` but found `()`
// Including cases where the default is using previous type params.
let _: HashMap<~str, int> = ();
//~^ ERROR mismatched types: expected `HashMap<~str,int>` but found `()`
let _: HashMap<~str, int, Hash<~str>> = ();
//~^ ERROR mismatched types: expected `HashMap<~str,int>` but found `()`
// But not when there's a different type in between.
let _: Foo<A, int, C> = ();
//~^ ERROR mismatched types: expected `Foo<A,int>` but found `()`

10
src/test/run-pass/generic-default-type-params.rs
View File

@ -52,6 +52,16 @@ fn default_foo(x: Foo) {
assert_eq!(x.baz(), (1, 'a'));
}
#[deriving(Eq)]
struct BazHelper<T>(T);
#[deriving(Eq)]
// Ensure that we can use previous type parameters in defaults.
struct Baz<T, U = BazHelper<T>, V = Option<U>>(T, U, V);
fn main() {
default_foo(Foo { a: (1, 'a') });
let x: Baz<bool> = Baz(true, BazHelper(false), Some(BazHelper(true)));
assert_eq!(x, Baz(true, BazHelper(false), Some(BazHelper(true))));
}