Experimental Physics and
Industrial Control System

[email protected] (Jeff Hill) · Fri, 5 Jun 1998 16:00:06 -0600

Jeff,

> gmake[1]: Entering directory
> `/projects/711/online_1/epics/v3_13b11/base/src/gdd/O.sgi'
> CC +p +w  -O   -DSGI  -I. -I..  -I../../../include -I../../../include
> -I../../../include/os/sgi -DUNIX     -c  ../genApps.cc
> "../aitTypes.h", line 83: error(3337): invalid redeclaration of type name
>           "timespec" (declared at line 11 of "/usr/include/sys/ptimers.h")
>   struct timespec

The current version of the conditional in aitTypes.h is:

#if (_POSIX_C_SOURCE < 3) && !defined(SOLARIS) && !defined(HP_UX) && !defined(linux)

It would appear that the trend is that all UNIX OS are providing this declaration
even if _POSIX_C_SOURCE is less than 3. The os that do not supply struct  timespec
are currently (I think) WIN32, VMS, CYGWIN32, ALPHA, and SUN4. It appears that 
struct timespec is supplied by SOLARIS, HPUX, LINUX, and SGI irregardless of
what _POSIX_C_SOURCE is set to. I will add only "!defined(sgi)" because I have
seen this elsewhere in the EPICS source code. I will not add "SGI" so that we can
keep the list reasonably short.

> I could not find where _POSIX_C_SOURCE is defined in the configure
> files.   Can someone tell me where I can set this variable so that the
> fix can avoid changing the code?  

Attached is a description of POSIX_C_SOURCE that I found on the internet.

PS: if anyone knows of a cleaner (read less maintenance) solution to this mess 
please send your suggestions.

Jeff

A new symbol, _POSIX_C_SOURCE was introduced in POSIX.2
(V1 P720, L51) as a mechanism to enable POSIX.1 and
POSIX.2 symbols. Its values are as follows:

/*
* Values of _POSIX_C_SOURCE
*
* undefined not a POSIX compilation
* 1 POSIX.1-1990 compilation
* 2 POSIX.2-1992 compilation
* 1993xxL POSIX.4-1993 compilation
*/

This means that POSIX.2 says that a value of 1 = POSIX.1
and a value of 2 = POSIX.1 & POSIX.2. The idea here is
to provide a single control point over the POSIX namespace,
rather than having to edit each file individually. 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System