False positive memory leak unless there is named return variable

[William Fulton]

Put the code posted at the bottom into file a file called runme.c and run cppcheck:

$ cppcheck runme.c 
Checking runme.c...
[runme.c:30]: (error) Memory leak: s.str
Checking runme.c: WORKAROUND...
$ 

The memory leak is a false positive unless WORKAROUND is defined. The workaround requires an extra temporary variable, which is odd!

// file runme.c
#include <string.h>
#include <stdlib.h>
#include <stdio.h>

typedef struct String {
  char *str;
} String;

typedef struct Object {
  String *data;
} Object;

Object * NewObject(String *s) {
  Object *obj = malloc(sizeof(Object));
  obj->data = s;
  return obj;
}

Object * NewString(const char *str) {
  String *s = malloc(sizeof(String));
  s->str = malloc(strlen(str) + 1);
  strcpy(s->str, str);
#if defined(WORKAROUND)
  {
    Object *obj = NewObject(s);
    return obj;
  }
#else
  return NewObject(s);
#endif
}

void DeleteObject(Object *o) {
  Object *obj = (Object *)o;
  String *s = (String *)obj->data;
  free(s->str);
  free(s);
  free(obj);
};

int main() {
  Object *obj = NewString("hello there");
  printf("%s\n", obj->data->str);
  DeleteObject(obj);
  return 0;
}

[CHR]

I can reproduce with v2.3.

[CHR]

I have created a ticket here: https://trac.cppcheck.net/ticket/10158