From 4336983087e5f96c1e0ba4b35e0338561270b7bf Mon Sep 17 00:00:00 2001
From: Stefan O'Rear <stefanor@cox.net>
Date: Tue, 10 Jan 2012 02:14:09 -0800
Subject: [PATCH] Treat subsets in MMD as base type + where

---
 lib/CodeGen.cs | 6 ++++++
 src/niecza     | 8 +++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/lib/CodeGen.cs b/lib/CodeGen.cs
index 727eb401..9b7431f0 100644
--- a/lib/CodeGen.cs
+++ b/lib/CodeGen.cs
@@ -4314,6 +4314,12 @@ public class DowncallReceiver : CallReceiver {
             subset.initVar = basety.initVar;
             return null;
         }
+        public static object type_get_basetype(object[] args) {
+            return Handle.Wrap(((STable)Handle.Unbox(args[1])).mo.superclasses[0]);
+        }
+        public static object type_get_type_var(object[] args) {
+            return Handle.Wrap(((STable)Handle.Unbox(args[1])).typeVar);
+        }
         public static object type_set_where(object[] args) {
             STable  subset = (STable)Handle.Unbox(args[1]);
             SubInfo where  = (SubInfo)Handle.Unbox(args[2]);
diff --git a/src/niecza b/src/niecza
index 24436812..c9392ec1 100644
--- a/src/niecza
+++ b/src/niecza
@@ -286,7 +286,13 @@ method parameter($/) {
                 ::Op::GeneralConst.new(value => $tc.ast<value>));
         } else {
             $/.CURSOR.sorry("Parameter coercion NYI") if $tc.ast<as>;
-            $/.ast.tclass = $tc.ast<type>;
+            my $type = $tc.ast<type>;
+            if $type.kind eq 'subset' {
+                push ($/.ast.where //= []), self.thunk_sub(
+                    ::Op::GeneralConst.new(value => $type.get_type_var));
+                $type = $type.get_basetype while $type.kind eq 'subset';
+            }
+            $/.ast.tclass = $type;
             $/.ast.flags +|= $tc.ast<tmode>;
         }
     }