c - What is the correct type to use for declaring a metavariable that possibly could match either variables or members in a struct? -

what correct type use declaring metavariable possibly match either variables or members in struct?

take instance following example source code:

#include <stdio.h> #include <stdlib.h>  struct some_struct {         int i;         char *s; };  void test(void) {         struct some_struct *ptr;         char *s;          s = malloc(100);         ptr = malloc(sizeof(struct some_struct));         ptr->s = malloc(100);          puts("done"); } 

with following semantic patch:

@@ identifier ptr; //idexpression ptr; //expression ptr; expression e; @@  ptr = malloc(e); +if (ptr == null) +       return; 

the ptr->s allocation not matched unless expression ptr used. use expression seems bit broadly me. correct , way it?

in general, want catch lvalue pointer - since you're matching places expression assigned value malloc, plain expression job fine (since non-pointer or non-lvalue should make compiler complain).

the problem you're going have if expression has sideeffects, eg:

struct some_struct *a[10]; int = 0;  a[i++] = malloc(sizeof(struct some_struct));