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rustc: Universally quantify regions when looking up typeclass implementations

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This commit is contained in:
Patrick Walton 2012-03-14 18:16:42 -07:00
parent a3d2882ffd
commit 383a801993
1 changed files with 17 additions and 1 deletions
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18
src/rustc/middle/typeck.rs
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@ -1466,6 +1466,17 @@ fn instantiate_self_regions(pcx: pat_ctxt, args: [ty::t]) -> [ty::t] {
})
}
// Replaces all region variables in the given type with "inferred regions".
// This is used during method lookup to allow typeclass implementations to
// refer to inferred regions.
fn universally_quantify_regions(tcx: ty::ctxt, ty: ty::t) -> ty::t {
if ty::type_has_rptrs(ty) {
ty::fold_ty(tcx, ty::fm_rptr({|_r| ty::re_inferred}), ty)
} else {
ty
}
}
fn check_pat_variant(pcx: pat_ctxt, pat: @ast::pat, path: @ast::path,
subpats: [@ast::pat], expected: ty::t) {
// Typecheck the path.
@ -1877,7 +1888,12 @@ fn lookup_method_inner(fcx: @fn_ctxt, expr: @ast::expr,
let {n_tps, ty: self_ty} = impl_self_ty(tcx, did);
let {vars, ty: self_ty} = if n_tps > 0u {
bind_params(fcx, self_ty, n_tps)
} else { {vars: [], ty: self_ty} };
} else {
{vars: [], ty: self_ty}
};
let ty = universally_quantify_regions(tcx, ty);
alt unify::unify(fcx, ty, self_ty) {
result::ok(_) {
if option::is_some(result) {