View Compilation Error

0_0_24364265_13361.cpp: In function 'bool cmp(node, node)':
0_0_24364265_13361.cpp:12:22: error: 'a' has incomplete type
 bool cmp(struct node a,struct node b) {
                      ^
0_0_24364265_13361.cpp:12:17: error: forward declaration of 'struct node'
 bool cmp(struct node a,struct node b) {
                 ^
0_0_24364265_13361.cpp:12:36: error: 'b' has incomplete type
 bool cmp(struct node a,struct node b) {
                                    ^
0_0_24364265_13361.cpp:12:17: error: forward declaration of 'struct node'
 bool cmp(struct node a,struct node b) {
                 ^