Support explicit discriminant numbers on tag variants.

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.

1 files changed, 5 insertions, 2 deletions

diff --git a/src/comp/middle/ty.rs b/src/comp/middle/ty.rs
index 76a9b4c69c7..dbd688de402 100644
--- a/src/comp/middle/ty.rs
+++ b/src/comp/middle/ty.rs
@@ -2686,7 +2686,8 @@ fn impl_iface(cx: ctxt, id: ast::def_id) -> option::t<t> {
 }
 
 // Tag information
-type variant_info = @{args: [ty::t], ctor_ty: ty::t, id: ast::def_id};
+type variant_info = @{args: [ty::t], ctor_ty: ty::t, id: ast::def_id,
+                      disr_val: int};
 
 fn tag_variants(cx: ctxt, id: ast::def_id) -> @[variant_info] {
     alt cx.tag_var_cache.find(id) {
@@ -2705,7 +2706,9 @@ fn tag_variants(cx: ctxt, id: ast::def_id) -> @[variant_info] {
                 } else { [] };
                 @{args: arg_tys,
                   ctor_ty: ctor_ty,
-                  id: ast_util::local_def(variant.node.id)}
+                  id: ast_util::local_def(variant.node.id),
+                  disr_val: variant.node.disr_val
+                 }
             })
           }
         }