was poking around in include/net.h, and noticed this snippet:

/* * Address Resolution Protocol (ARP) header. */ struct arp_hdr {

... snip ...

#define ar_sha ar_data[0] #define ar_spa ar_data[ARP_HLEN] #define ar_tha ar_data[ARP_HLEN + ARP_PLEN] #define ar_tpa ar_data[ARP_HLEN + ARP_PLEN + ARP_HLEN] #if 0 u8 ar_sha[]; /* Sender hardware address */ u8 ar_spa[]; /* Sender protocol address */ u8 ar_tha[]; /* Target hardware address */ u8 ar_tpa[]; /* Target protocol address */ #endif /* 0 */ };

i just checked, and that "#if 0" has been there since 2002:

2d966958 (Wolfgang Denk 2002-10-31 22:12:35 +0000 421) #if 0 717234e0 (Sergey Temerkhanov 2015-04-08 01:41:23 -0500 422) u8 ar_sha[]; /* Sender hardware address */ 717234e0 (Sergey Temerkhanov 2015-04-08 01:41:23 -0500 423) u8 ar_spa[]; /* Sender protocol address */ 717234e0 (Sergey Temerkhanov 2015-04-08 01:41:23 -0500 424) u8 ar_tha[]; /* Target hardware address */ 717234e0 (Sergey Temerkhanov 2015-04-08 01:41:23 -0500 425) u8 ar_tpa[]; /* Target protocol address */ 2d966958 (Wolfgang Denk 2002-10-31 22:12:35 +0000 426) #endif /* 0 */

is it doing anything, like acting as a comment or something?

rday

p.s. there's quite a lot of "#if 0" throughout the source code, some of which i may submit patches to get rid of just in the areas i'm confortable with.