Fix some build warnings

paddle/function/TensorShapeTest.cpp

@@ -44,7 +44,7 @@ TEST(TensorShape, GetAndSet) {
   EXPECT_EQ(t.ndims(), 3U);
   EXPECT_EQ(t.getElements(), 6U);
 
-  EXPECT_EQ(t[1], 2);
+  EXPECT_EQ(t[1], 2U);
   t.setDim(1, 100);
   EXPECT_EQ(t.getElements(), 300U);
   EXPECT_EQ(t[1], 100U);

paddle/gserver/layers/SubNestedSequenceLayer.cpp

@@ -96,7 +96,7 @@ void SubNestedSequenceLayer::calSelectedCols(
   for (size_t i = 0; i < seqNum; ++i) {
     for (size_t j = 0; j < beamSize; ++j) {
       if (selectedIndices->getElement(i, j) == -1.) break;
-      int selSubSeqIdx = selectedIndices->getElement(i, j);
+      size_t selSubSeqIdx = selectedIndices->getElement(i, j);
       CHECK_GT(inputSeqInfoVec_[i].size() - 1, selSubSeqIdx);
 
       size_t subSeqLen = inputSeqInfoVec_[i][selSubSeqIdx + 1] -