Fix incorrect overloading resolution for polymorphic functions when called with empty set literals as arguments. Fix handling of duplicate polymorphic function definitions with empty bodies. Fixes #875.

Author: guidotack

changes.rst

@@ -40,6 +40,10 @@ Bug fixes:
    the bounds cannot be computed (:bugref:`917`).
 -  Fix an incorrect comparison function that could trigger assertions in debug builds
    (and likely incorrect behaviour in optimised builds).
+-  Fix incorrect overloading resolution for polymorphic functions when called
+   with empty set literals as arguments (:bugref:`875`).
+-  Fix handling of duplicate polymorphic function definitions with empty bodies
+   (:bugref:`875`).
 
 .. _v2.9.3:
 

lib/ast.cpp

@@ -1569,13 +1569,13 @@ Type return_type(EnvI& env, FunctionI* fi, const std::vector<T>& ta, Expression*
     if (tii->ranges().size() == 1 && isa_tiid(tii->ranges()[0]->domain())) {
       ASTString tiid = Expression::cast<TIId>(tii->ranges()[0]->domain())->v();
       Type orig_tiit = get_type(cur.second);
-      if (orig_tiit.dim() == 0) {
+      if (orig_tiit.dim() == 0 && !orig_tiit.isSet()) {
         std::ostringstream ss;
         ss << "type-inst variable $" << tiid << " must be an array index";
         throw TypeError(env, get_loc(cur.second, call, fi), ss.str());
       }
-      Type tiit = Type::top(orig_tiit.dim());
-      if (orig_tiit.typeId() != 0) {
+      Type tiit = Type::top(orig_tiit.dim() == 0 && orig_tiit.isSet() ? 1 : orig_tiit.dim());
+      if (orig_tiit.typeId() != 0 && orig_tiit.dim() != 0) {
         std::vector<unsigned int> enumIds = env.getArrayEnum(orig_tiit.typeId());
         enumIds[enumIds.size() - 1] = 0;
         tiit.typeId(env.registerArrayEnum(enumIds));

lib/model.cpp

@@ -480,7 +480,9 @@ bool Model::registerFn(EnvI& env, FunctionI* fi, bool keepSorted, bool throwIfDu
               fi->ann().add(deprecated);
             }
             FunctionI* old_fi = i.fi;
-            i = FnEntry(env, fi);
+            if (!fe.isPolymorphic) {
+              i = fe;
+            }
             // If we are replacing a polymorphic function using a new polymorphic function, then
             // replace in all entries generated using addPolymorphicInstances
             if (i.isPolymorphic) {
@@ -924,10 +926,11 @@ FunctionI* Model::matchFn(EnvI& env, const ASTString& id, const std::vector<Expr
   if (matched.size() == 1) {
     return matched[0];
   }
-  Type t = matched[0]->ti()->type();
+  auto t = matched[0]->rtype(env, args, nullptr, false);
   t.mkPar(env);
   for (unsigned int i = 1; i < matched.size(); i++) {
-    if (!env.isSubtype(t, matched[i]->ti()->type(), strictEnums)) {
+    auto rt = matched[i]->rtype(env, args, nullptr, false);
+    if (!env.isSubtype(t, rt, strictEnums)) {
       throw TypeError(env, Expression::loc(botarg),
                       "ambiguous overloading on return type of function");
     }

tests/spec/unit/compilation/test_bug_875.mzn

@@ -0,0 +1,9 @@
+/***
+!Test
+solvers: [gecode]
+expected: !Result
+  solution: !Solution
+***/
+
+function set of $T: 'union'(set of $T:x, set of $T: y);
+any: x = {1,2,3} union {};