[BUILD] Fix reflection build for gcc-8 (#1304)

dmlc-core @ e864aa67

-Subproject commit 9b3f9753ae81d657743c555e0cacc4e43f0bed2d
+Subproject commit e864aa6757cdbe78b1296fe5231fd3050b7802c3

src/lang/reflection.cc

@@ -375,41 +375,43 @@ class NodeAttrSetter : public AttrVisitor {
   std::string type_key;
   std::unordered_map<std::string, runtime::TVMArgValue> attrs;
 
-  template<typename T>
-  void SetValue(const char* key, T* value) {
-    auto it = attrs.find(key);
-    if (it == attrs.end()) {
-      LOG(FATAL) << type_key << ": require field " << key;
-    }
-    *value = it->second.operator T();
-    attrs.erase(it);
-  }
   void Visit(const char* key, double* value) final {
-    SetValue(key, value);
+    *value = GetAttr(key).operator double();
   }
   void Visit(const char* key, int64_t* value) final {
-    SetValue(key, value);
+    *value = GetAttr(key).operator int64_t();
   }
   void Visit(const char* key, uint64_t* value) final {
-    SetValue(key, value);
+    *value = GetAttr(key).operator uint64_t();
   }
   void Visit(const char* key, int* value) final {
-    SetValue(key, value);
+    *value = GetAttr(key).operator int();
   }
   void Visit(const char* key, bool* value) final {
-    SetValue(key, value);
+    *value = GetAttr(key).operator bool();
   }
   void Visit(const char* key, std::string* value) final {
-    SetValue(key, value);
+    *value = GetAttr(key).operator std::string();
   }
   void Visit(const char* key, void** value) final {
-    SetValue(key, value);
+    *value = GetAttr(key).operator void*();
   }
   void Visit(const char* key, Type* value) final {
-    SetValue(key, value);
+    *value = GetAttr(key).operator Type();
   }
   void Visit(const char* key, NodeRef* value) final {
-    SetValue(key, value);
+    *value = GetAttr(key).operator NodeRef();
+  }
+
+ private:
+  runtime::TVMArgValue GetAttr(const char* key) {
+    auto it = attrs.find(key);
+    if (it == attrs.end()) {
+      LOG(FATAL) << type_key << ": require field " << key;
+    }
+    runtime::TVMArgValue v = it->second;
+    attrs.erase(it);
+    return v;
   }
 };
 

src/pass/unroll_loop.cc

@@ -29,14 +29,14 @@ class LoopUnroller : public IRMutator {
 
   Stmt Mutate_(const AttrStmt* op, const Stmt& stmt) final {
     if (op->attr_key == "pragma_auto_unroll_max_step") {
-      int value;
+      int value = 0;
       CHECK(arith::GetConstInt(op->value, &value));
       std::swap(value, auto_max_step_);
       Stmt ret = this->Mutate(op->body);
       std::swap(value, auto_max_step_);
       return ret;
     } else if (op->attr_key == "pragma_unroll_explicit") {
-      int value;
+      int value = 0;
       CHECK(arith::GetConstInt(op->value, &value));
       bool explicit_unroll = value;
       std::swap(explicit_unroll, explicit_unroll_);