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rustc: Have demand_pat() extract type parameters from tags. Add a test case.

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This commit is contained in:
Patrick Walton 2011-03-09 14:09:02 -08:00
parent 2986ed43e9
commit 603d820b85
2 changed files with 30 additions and 8 deletions
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27
src/comp/middle/typeck.rs
View File

@ -1071,15 +1071,25 @@ fn demand_pat(&@fn_ctxt fcx, @ty.t expected, @ast.pat pat) -> @ast.pat {
case (ast.pat_tag(?id, ?subpats, ?vdef_opt, ?ann)) {
auto t = demand(fcx, pat.span, expected, ann_to_type(ann));
// Figure out the type parameters of the tag.
auto tag_id = option.get[ast.variant_def](vdef_opt)._0;
auto ty_params = fcx.ccx.item_ty_params.get(tag_id);
// Take the type parameters out of the expected type.
auto ty_param_substs;
alt (t.struct) {
case (ty.ty_tag(_, ?tps)) { ty_param_substs = tps; }
case (_) {
log "demand_pat(): expected type for tag pat isn't " +
"actually a tag?!";
fail;
}
}
// The type of the tag isn't enough; we also have to get the type
// of the variant, which is either a tag type in the case of
// nullary variants or a function type in the case of n-ary
// variants.
//
// TODO: When we have type-parametric tags, this will get a little
// trickier. Basically, we have to instantiate the variant type we
// acquire here with the type parameters provided to us by
// "expected".
auto vdef = option.get[ast.variant_def](vdef_opt);
auto variant_ty = fcx.ccx.item_types.get(vdef._1);
@ -1088,18 +1098,19 @@ fn demand_pat(&@fn_ctxt fcx, @ty.t expected, @ast.pat pat) -> @ast.pat {
alt (variant_ty.struct) {
case (ty.ty_tag(_, _)) {
// Nullary tag variant.
// TODO: ty param substs
check (subpats_len == 0u);
p_1 = ast.pat_tag(id, subpats, vdef_opt,
ast.ann_type(t, none[vec[@ty.t]]));
}
case (ty.ty_fn(_, ?args, ?tag_ty)) {
// N-ary tag variant.
// TODO: ty param substs
let vec[@ast.pat] new_subpats = vec();
auto i = 0u;
for (arg a in args) {
auto new_subpat = demand_pat(fcx, a.ty, subpats.(i));
auto subpat_ty = substitute_ty_params(fcx.ccx, a.ty,
ty_params, ty_param_substs, pat.span);
auto new_subpat = demand_pat(fcx, subpat_ty,
subpats.(i));
new_subpats += vec(new_subpat);
i += 1u;
}

11
src/test/run-pass/simple-generic-alt.rs Normal file
View File

@ -0,0 +1,11 @@
tag clam[T] {
a(T);
}
fn main() {
auto c = a(2);
alt (c) {
case (a[int](_)) {}
}
}