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Support explicit discriminant numbers on tag variants.

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Addresses issue #1393.

For now disallow disr. values unless all variants use nullary
contractors (i.e. "enum-like").

Disr. values are now encoded in the crate metadata, but only when it
will differ from the inferred value based on the order.
This commit is contained in:
Kevin Atkinson 2012-01-10 14:50:40 -07:00 • committed by Graydon Hoare
parent d0fe6723fc
commit 08abf8d37f
12 changed files with 167 additions and 30 deletions
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20
src/comp/metadata/decoder.rs
View file

@ -88,6 +88,17 @@ fn variant_tag_id(d: ebml::doc) -> ast::def_id {
ret parse_def_id(ebml::doc_data(tagdoc));
}
fn variant_disr_val(d: ebml::doc) -> option::t<int> {
alt ebml::maybe_get_doc(d, tag_disr_val) {
some(val_doc) {
let val_buf = ebml::doc_data(val_doc);
let val = int::parse_buf(val_buf, 10u);
ret some(val);
}
_ { ret none;}
}
}
fn doc_type(doc: ebml::doc, tcx: ty::ctxt, cdata: cmd) -> ty::t {
let tp = ebml::get_doc(doc, tag_items_data_item_type);
parse_ty_data(tp.data, cdata.cnum, tp.start, tcx, {|did|
@ -240,6 +251,7 @@ fn get_tag_variants(cdata: cmd, id: ast::node_id, tcx: ty::ctxt)
let item = find_item(id, items);
let infos: [ty::variant_info] = [];
let variant_ids = tag_variant_ids(item, cdata);
let disr_val = 0;
for did: ast::def_id in variant_ids {
let item = find_item(did.node, items);
let ctor_ty = item_type(item, tcx, cdata);
@ -250,7 +262,13 @@ fn get_tag_variants(cdata: cmd, id: ast::node_id, tcx: ty::ctxt)
}
_ { /* Nullary tag variant. */ }
}
infos += [@{args: arg_tys, ctor_ty: ctor_ty, id: did}];
alt variant_disr_val(item) {
some(val) { disr_val = val; }
_ { /* empty */ }
}
infos += [@{args: arg_tys, ctor_ty: ctor_ty, id: did,
disr_val: disr_val}];
disr_val += 1;
}
ret infos;
}