Fix warnings

paddle/fluid/framework/mixed_vector.h

@@ -121,6 +121,10 @@ class Vector {
   const T* begin() const { return &this->operator[](0); }
   const T* end() const { return &this->operator[](size()); }
 
+  const T* cbegin() const { return begin(); }
+
+  const T* cend() const { return end(); }
+
   const T& back() const {
     auto it = end();
     --it;
@@ -243,7 +247,8 @@ class Vector {
 
   bool operator==(const Vector<T>& other) const {
     if (size() != other.size()) return false;
-    for (auto it1 = begin(), it2 = other.begin(); it1 < end(); ++it1, ++it2) {
+    for (const T *it1 = cbegin(), it2 = other.cbegin(); it1 < cend();
+         ++it1, ++it2) {
       if (*it1 != *it2) {
         return false;
       }

paddle/fluid/framework/mixed_vector_test.cu

@@ -27,10 +27,10 @@ TEST(mixed_vector, CPU_VECTOR) {
   for (int i = 0; i < 10; ++i) {
     tmp.push_back(i);
   }
-  ASSERT_EQ(tmp.size(), 10);
+  ASSERT_EQ(tmp.size(), 10UL);
   vec<int> tmp2;
   tmp2 = tmp;
-  ASSERT_EQ(tmp2.size(), 10);
+  ASSERT_EQ(tmp2.size(), 10UL);
   for (int i = 0; i < 10; ++i) {
     ASSERT_EQ(tmp2[i], i);
     ASSERT_EQ(tmp2[i], tmp[i]);
@@ -59,7 +59,7 @@ TEST(mixed_vector, GPU_VECTOR) {
   for (int i = 0; i < 10; ++i) {
     tmp.push_back(i);
   }
-  ASSERT_EQ(tmp.size(), 10);
+  ASSERT_EQ(tmp.size(), 10UL);
   paddle::platform::CUDAPlace gpu(0);
 
   multiply_10<<<1, 1, 0, GetCUDAStream(gpu)>>>(tmp.MutableData(gpu));
@@ -80,7 +80,7 @@ TEST(mixed_vector, MultiGPU) {
   for (int i = 0; i < 10; ++i) {
     tmp.push_back(i);
   }
-  ASSERT_EQ(tmp.size(), 10);
+  ASSERT_EQ(tmp.size(), 10UL);
   paddle::platform::CUDAPlace gpu0(0);
   paddle::platform::SetDeviceId(0);
   multiply_10<<<1, 1, 0, GetCUDAStream(gpu0)>>>(tmp.MutableData(gpu0));