[BUGFIX] Treatment of non-variadic operands after variadic operands.

- There was a confusion of the index of the variadic ODS operand (i) and the index of its first occurrences (idx).
- Added a test case which triggered an error before this fix.

src/compiler/lowering/RewriteToCallKernelOpPass.cpp

@@ -268,7 +268,7 @@ namespace
                     }
                     else
                         // Non-variadic operand.
-                        newOperands.push_back(op->getOperand(i));
+                        newOperands.push_back(op->getOperand(idx));
                 }
             }
             else

test/api/cli/operations/OperationsTest.cpp

@@ -49,6 +49,7 @@ MAKE_TEST_CASE("operator_minus", 1)
 MAKE_TEST_CASE("operator_plus", 2)
 MAKE_TEST_CASE("operator_slash", 1)
 MAKE_TEST_CASE("operator_times", 1)
+MAKE_TEST_CASE("order", 1)
 MAKE_TEST_CASE("rbind", 1)
 MAKE_TEST_CASE("recode", 3)
 MAKE_TEST_CASE("replace", 1)

test/api/cli/operations/order_1.daphne

@@ -0,0 +1,14 @@
+// Order a matrix by three columns.
+
+// This test case was added to test the correct treatment of
+// the non-variadic last parameter (returnIdxs) after two
+// longer variadic parameters (colIdxs, ascs). There used to
+// be a bug that was only triggered when an unproblematic (res1)
+// and a problematic (res2) use were combined in the same
+// DaphneDSL script.
+
+X = reshape(seq(1, 6, 1), 2, 3);
+res1 = order(X, 0, 1,    false, false,        false);
+res2 = order(X, 0, 1, 2, false, false, false, false);
+print(res1);
+print(res2);

test/api/cli/operations/order_1.txt

@@ -0,0 +1,6 @@
+DenseMatrix(2x3, int64_t)
+4 5 6
+1 2 3
+DenseMatrix(2x3, int64_t)
+4 5 6
+1 2 3