Using if directives in headers

I have a working generic graph. The type for vertex is currently defined as:

typedef struct vertex {  void *data;  char *label;  bool inGraph;} vertex;

The void pointer can then be customized for any algorithm, like BFS, DFS, etc. This works, but I want to simplify the code by using a separate header file for a vertex that specifies its type as needed, and is included in graph.h. Something like this:

#ifndef VERTEX_H_INCLUDED#define VERTEX_H_INCLUDED#include <stdlib.h>#include <stdbool.h>#if defined (GRAPH_VERTEX1)typedef struct vertex {  struct vertex *parent;        char *label;          bool inGraph;       } vertex;#elif defined (GRAPH_VERTEX2)typedef struct vertex {  size_t dist;      char *label;          bool inGraph;       } vertex;#else  // defaulttypedef struct vertex {     char *label;          bool inGraph;       } vertex;#endif#endif

This does not work, however. The right vertex type is not selected and allocated.

I have made an example to reproduce the issue.

main.c

#include <stdio.h>#define GRAPH_VERTEX1#include "graph.h"int main() {  vertex *v = createVertex("test");  v->inGraph = true;  vertex *parent = createVertex("parent");  printf("Vertex: %s\n", v->label);  printf("Parent: %s\n", parent->label);  printf("In graph: %d\n", parent->inGraph);  freeVertex(v);  freeVertex(parent);  return 0;}

graph.h

#ifndef GRAPH_H_INCLUDED#define GRAPH_H_INCLUDED#include <stdlib.h>#include "vertex.h"vertex *createVertex(char *label);void freeVertex(vertex *v);#endif

graph.c

#include "graph.h"#include <string.h>vertex *createVertex(char *label) {  vertex *v = calloc(1, sizeof(vertex));  v->label = calloc(strlen(label) + 1, sizeof(char));  v->inGraph = false;  strcpy(v->label, label);  return v;}void freeVertex(vertex *v) {  free(v->label);  free(v);}

The example works fine if I put a single definition in vertex.h. However, if I try to use the if directives, I get the following errors:

==986== Memcheck, a memory error detector==986== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.==986== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info==986== Command: ./a.out==986====986== Invalid write of size 1==986==    at 0x1090FD: main ==986==  Address 0x4a8e050 is 0 bytes after a block of size 16 alloc'd==986==    at 0x484DA83: calloc ==986==    by 0x109279: createVertex ==986==    by 0x1090F5: main ==986====986== Invalid read of size 1==986==    at 0x10913A: main ==986==  Address 0x4a8e0f0 is 0 bytes after a block of size 16 alloc'd==986==    at 0x484DA83: calloc ==986==    by 0x109279: createVertex ==986==    by 0x109108: main ==986==Vertex: (null)Parent: (null)In graph: 0==986== ==986== HEAP SUMMARY:==986==     in use at exit: 0 bytes in 0 blocks==986==   total heap usage: 5 allocs, 5 frees, 4,140 bytes allocated==986====986== All heap blocks were freed -- no leaks are possible==986====986== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)==986====986== 1 errors in context 1 of 2:==986== Invalid read of size 1==986==    at 0x10913A: main ==986==  Address 0x4a8e0f0 is 0 bytes after a block of size 16 alloc'd==986==    at 0x484DA83: calloc ==986==    by 0x109279: createVertex ==986==    by 0x109108: main ==986====986====986== 1 errors in context 2 of 2:==986== Invalid write of size 1==986==    at 0x1090FD: main ==986==  Address 0x4a8e050 is 0 bytes after a block of size 16 alloc'd==986==    at 0x484DA83: calloc ==986==    by 0x109279: createVertex ==986==    by 0x1090F5: main ==986====986== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)