[cfe-dev] #ifndef not working

[Chris Lattner]

On Aug 29, 2007, at 12:50 PM, Patrick Flannery wrote:

> The following code will cause a segfault.
>
> #include "/usr/lib/gcc/xb6_64-redhat-linux/4.1.1/include/stddef.h"
>
> #ifndef offsetof
> #define offsetof (TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
> #endif

I'm pretty sure ifndef works.  Can you elaborate on the problem  
you're hitting?  I don't have "/usr/lib/gcc/xb6_64-redhat-linux/4.1.1/ 
include/stddef.h".  When I changed it to just #include "stddef.h", I  
get:

t.c:19:5: error: use of undeclared identifier 'intcode'
     intcode->c_regs_pos = offsetof(struct external_sun3_core, c_regs);
     ^
1 diagnostic generated.

with no crash.

-chris

>
> struct external_sun3_core
> {
>     size_t c_regs;
> };
> struct internal_sunos_core
> {
>     size_t c_regs_pos;
>     size_t c_regs_size;
> };
> static void swap(char * ext, struct internal_sunos_code *intcore)
> {
>     struct external_sun3_core * extcore = (struct  
> external_sun3_core *) ext;
>     intcode->c_regs_pos = offsetof(struct external_sun3_core, c_regs);
> }
>
> Patrick
>
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