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Improve handling of trait bounds on a trait in default methods.

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This is work on #7460.
It does not properly handle certain cross crate situations,
because we don't properly export vtable resolution information.
This commit is contained in:
Michael Sullivan 2013-06-28 11:18:09 -07:00
parent 649b26f7c6
commit 0252693db2
2 changed files with 93 additions and 39 deletions
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96
src/librustc/middle/trans/callee.rs
View File

@ -195,6 +195,58 @@ pub fn trans_fn_ref_with_vtables_to_callee(
type_params, vtables))}
}
fn get_impl_resolutions(bcx: block,
impl_id: ast::def_id)
-> typeck::vtable_res {
if impl_id.crate == ast::local_crate {
*bcx.ccx().maps.vtable_map.get(&impl_id.node)
} else {
// XXX: This is a temporary hack to work around not properly
// exporting information about resolutions for impls.
// This doesn't actually work if the trait has param bounds,
// but it does allow us to survive the case when it does not.
let trait_ref = ty::impl_trait_ref(bcx.tcx(), impl_id).get();
@vec::from_elem(trait_ref.substs.tps.len(), @~[])
}
}
fn resolve_default_method_vtables(bcx: block,
impl_id: ast::def_id,
method: &ty::Method,
substs: &ty::substs,
impl_vtables: Option<typeck::vtable_res>)
-> typeck::vtable_res {
// Get the vtables that the impl implements the trait at
let trait_vtables = get_impl_resolutions(bcx, impl_id);
// Build up a param_substs that we are going to resolve the
// trait_vtables under.
let param_substs = Some(@param_substs {
tys: copy substs.tps,
self_ty: substs.self_ty,
vtables: impl_vtables,
self_vtable: None
});
let trait_vtables_fixed = resolve_vtables_under_param_substs(
bcx.tcx(), param_substs, trait_vtables);
// Now we pull any vtables for parameters on the actual method.
let num_method_vtables = method.generics.type_param_defs.len();
let method_vtables = match impl_vtables {
Some(vtables) => {
let num_impl_type_parameters =
vtables.len() - num_method_vtables;
vtables.tailn(num_impl_type_parameters).to_owned()
},
None => vec::from_elem(num_method_vtables, @~[])
};
@(*trait_vtables_fixed + method_vtables)
}
pub fn trans_fn_ref_with_vtables(
bcx: block, //
def_id: ast::def_id, // def id of fn
@ -246,9 +298,9 @@ pub fn trans_fn_ref_with_vtables(
// We need to do a bunch of special handling for default methods.
// We need to modify the def_id and our substs in order to monomorphize
// the function.
let (def_id, opt_impl_did, substs, self_vtable) =
let (def_id, opt_impl_did, substs, self_vtable, vtables) =
match tcx.provided_method_sources.find(&def_id) {
None => (def_id, None, substs, None),
None => (def_id, None, substs, None, vtables),
Some(source) => {
// There are two relevant substitutions when compiling
// default methods. First, there is the substitution for
@ -282,49 +334,31 @@ pub fn trans_fn_ref_with_vtables(
let self_vtable =
typeck::vtable_static(source.impl_id, receiver_substs,
receiver_vtables);
// XXX: I think that if the *trait* has vtables on it,
// it is all over
// Compute the first substitution
let first_subst = make_substs_for_receiver_types(
tcx, source.impl_id, trait_ref, method);
// And compose them
let new_substs = first_subst.subst(tcx, &substs);
let vtables =
resolve_default_method_vtables(bcx, source.impl_id,
method, &new_substs, vtables);
debug!("trans_fn_with_vtables - default method: \
substs = %s, trait_subst = %s, \
first_subst = %s, new_subst = %s",
first_subst = %s, new_subst = %s, \
self_vtable = %s, vtables = %s",
substs.repr(tcx), trait_ref.substs.repr(tcx),
first_subst.repr(tcx), new_substs.repr(tcx));
first_subst.repr(tcx), new_substs.repr(tcx),
self_vtable.repr(tcx), vtables.repr(tcx));
(source.method_id, Some(source.impl_id),
new_substs, Some(self_vtable))
new_substs, Some(self_vtable), Some(vtables))
}
};
// XXX: this is *completely* bad and wrong. I feel bad. Handling
// of vtables is currently bogus for default methods, and changing
// to an unflattented representation of vtables causes this to
// show up in cases that it did not previously. We need to make
// the vtables list be the same length as the substs. There is
// nothing right about this. I really need to emphasize just how
// wrong it is: it is completely wrong.
// XXX: bad.
// This will be fixed in the next commit.
let vtables = do vtables.map |vtbls| {
if vtbls.len() < substs.tps.len() {
@(vec::from_elem(substs.tps.len() - vtbls.len(), @~[]) +
**vtbls)
} else if vtbls.len() > substs.tps.len() {
@vtbls.tailn(vtbls.len() - substs.tps.len()).to_owned()
} else {
*vtbls
}
};
// Check whether this fn has an inlined copy and, if so, redirect
// def_id to the local id of the inlined copy.
let def_id = {

36
src/librustc/middle/trans/common.rs
View File

@ -1035,18 +1035,37 @@ pub fn node_vtables(bcx: block, id: ast::node_id)
pub fn resolve_vtables_in_fn_ctxt(fcx: fn_ctxt, vts: typeck::vtable_res)
-> typeck::vtable_res {
@vec::map(*vts, |ds|
@vec::map(**ds, |d| resolve_vtable_in_fn_ctxt(fcx, copy *d)))
resolve_vtables_under_param_substs(fcx.ccx.tcx,
fcx.param_substs,
vts)
}
pub fn resolve_vtables_under_param_substs(tcx: ty::ctxt,
param_substs: Option<@param_substs>,
vts: typeck::vtable_res)
-> typeck::vtable_res {
@vec::map(*vts, |ds|
@vec::map(**ds, |d|
resolve_vtable_under_param_substs(tcx, param_substs, copy *d)))
}
// Apply the typaram substitutions in the fn_ctxt to a vtable. This should
// eliminate any vtable_params.
pub fn resolve_vtable_in_fn_ctxt(fcx: fn_ctxt, vt: typeck::vtable_origin)
-> typeck::vtable_origin {
let tcx = fcx.ccx.tcx;
resolve_vtable_under_param_substs(fcx.ccx.tcx,
fcx.param_substs,
vt)
}
pub fn resolve_vtable_under_param_substs(tcx: ty::ctxt,
param_substs: Option<@param_substs>,
vt: typeck::vtable_origin)
-> typeck::vtable_origin {
match vt {
typeck::vtable_static(trait_id, tys, sub) => {
let tys = match fcx.param_substs {
let tys = match param_substs {
Some(substs) => {
do vec::map(tys) |t| {
ty::subst_tps(tcx, substs.tys, substs.self_ty, *t)
@ -1054,11 +1073,12 @@ pub fn resolve_vtable_in_fn_ctxt(fcx: fn_ctxt, vt: typeck::vtable_origin)
}
_ => tys
};
typeck::vtable_static(trait_id, tys,
resolve_vtables_in_fn_ctxt(fcx, sub))
typeck::vtable_static(
trait_id, tys,
resolve_vtables_under_param_substs(tcx, param_substs, sub))
}
typeck::vtable_param(n_param, n_bound) => {
match fcx.param_substs {
match param_substs {
Some(substs) => {
find_vtable(tcx, substs, n_param, n_bound)
}
@ -1070,7 +1090,7 @@ pub fn resolve_vtable_in_fn_ctxt(fcx: fn_ctxt, vt: typeck::vtable_origin)
}
}
typeck::vtable_self(_trait_id) => {
match fcx.param_substs {
match param_substs {
Some(@param_substs
{self_vtable: Some(ref self_vtable), _}) => {
copy *self_vtable