Fix for concat op shape function (empty shapes) (#167)

Signed-off-by: AlexDBlack <blacka101@gmail.com>

libnd4j/include/ops/declarable/generic/transforms/concat.cpp

@@ -167,9 +167,7 @@ DECLARE_SHAPE_FN(concat) {
     }
 
     for(int i = 1; i < numOfArrs; ++i)
-        if (!shape::isEmpty(arrShapes[i])) {
+        outShapeInfo[axis + 1] += arrShapes[i][axis + 1];
-            outShapeInfo[axis + 1] += arrShapes[i][axis + 1];
-        }
 
     ShapeUtils::updateStridesAndType(outShapeInfo, arrShapes[0], shape::order(arrShapes[0]));
 

nd4j/nd4j-backends/nd4j-tests/src/test/java/org/nd4j/autodiff/opvalidation/ShapeOpValidation.java

@@ -2109,6 +2109,38 @@ public class ShapeOpValidation extends BaseOpValidation {
         Nd4j.exec(op);
     }
 
+    @Test
+    public void testConcatEmpty2(){
+        INDArray empty10a = Nd4j.create(DataType.INT, 1, 0);
+        INDArray empty10b = Nd4j.create(DataType.INT, 1, 0);
+
+        DynamicCustomOp op = DynamicCustomOp.builder("concat")
+                .addInputs(empty10a, empty10b)
+                .addIntegerArguments(0) //axis = 0
+                .build();
+
+        List<LongShapeDescriptor> l = op.calculateOutputShape();
+        assertEquals(1, l.size());
+        assertTrue(l.get(0).isEmpty());
+        assertArrayEquals(new long[]{2, 0}, l.get(0).getShape());
+        assertEquals(DataType.INT, l.get(0).dataType());
+
+        op.addOutputArgument(Nd4j.create(DataType.INT, 2, 0));
+        Nd4j.exec(op);
+
+
+        op = DynamicCustomOp.builder("concat")
+                .addInputs(empty10a, empty10b)
+                .addIntegerArguments(1) //axis = 1
+                .build();
+        l = op.calculateOutputShape();
+        assertEquals(1, l.size());
+        assertTrue(l.get(0).isEmpty());
+        assertArrayEquals(new long[]{1, 0}, l.get(0).getShape());
+        op.addOutputArgument(Nd4j.create(DataType.INT, 1, 0));
+        Nd4j.exec(op);
+    }
+
     @Test
     public void testEmptyGather(){
         /*
@@ -2434,4 +2466,5 @@ public class ShapeOpValidation extends BaseOpValidation {
                 .addInputs(Nd4j.createFromArray(1, 0))
                 .build();
     }
+
 }