Re: missing isinf declaration on solaris

Oskari Saarenmaa <os(at)ohmu(dot)fi> writes:
> GCC 4.9 build on Solaris 10 shows these warnings about isinf:
> float.c: In function 'is_infinite':
> float.c:178:2: warning: implicit declaration of function 'isinf'

Ugh.

> isinf declaration is in <iso/math_c99.h> which is included by <math.h>,
> but it's surrounded by #if defined(_STDC_C99) || _XOPEN_SOURCE - 0 >=
> 600 || defined(__C99FEATURES__). A couple of quick Google searches
> suggests that some other projects have worked around this by always
> defining __C99FEATURES__ even if compiling in C89 mode. __C99FEATURES__
> is only used by math.h and fenv.h in /usr/include.

> Should we just add -D__C99FEATURES__ to CPPFLAGS in
> src/template/solaris, add our own declaration of isinf() or do something
> else about the warning?

I'm worried that __C99FEATURES__ might do other, not-so-C89-compatible
things in later Solaris releases. Possibly that risk could be addressed
by having src/template/solaris make an OS version check before adding the
switch, but it'd be a bit painful probably.

Based on the #if you show, I'd be more inclined to think about defining
_XOPEN_SOURCE to get the result. There is precedent for that in
src/template/hpux which does
CPPFLAGS="$CPPFLAGS -D_XOPEN_SOURCE_EXTENDED"
I forget what-all _XOPEN_SOURCE_EXTENDED enables exactly, but if memory
serves there were a nontrivial number of now-considered-standard features
turned on by that in ancient HPUX releases. If you want to pursue this
route, you'd need to do a bit of digging to see what else _XOPEN_SOURCE
controls in Solaris and if there is some front-end feature macro (like
_XOPEN_SOURCE_EXTENDED) that you're supposed to set instead of touching
it directly.

regards, tom lane