Re: [Plplot-devel] [plplot:bugs] #179 Detection of snprintf fails with VC14 (fwd)

[Alan W. I. <ir...@be...>]

On 2015-09-03 22:06+0100 Phil Rosenberg wrote:

> [...] Note that both snprintf and _snprintf are listed as not found by
> cmake. But this isn't a blanket loss of the check_function_exists()
> function. isnan and isfinite are both found and I presume they use
> check_function_exists()?
>
> I then reread your email and found you provided a rather shorter test.
> I dumped this in a cmakelists.txt file and this could not find
> snprintf either
>
>
> I figured we can't be the only people having this issue so I googled
> it and found this page
> http://public.kitware.com/Bug/bug_relationship_graph.php?bug_id=15659&graph=relation
>
> It seems that snprintf and a number of other io related functions are
> now defined inline in stdio.h. This explains my linker errors above
> when shapelib was included - snprintf was not found because it is no
> longer in the library. The answer apparently is to use
> CheckSymbolExists instead.
>
> The following works correctly
>
> cmake_minimum_required(VERSION 2.8.9)
> project(test_check C)
> include(CheckSymbolExists)
> check_symbol_exists(snprintf stdio.h PL_HAVE_SNPRINTF)
> message(STATUS "PL_HAVE_SNPRINTF = ${PL_HAVE_SNPRINTF}")

> So this is really nothing to do with the new "Universal" nature of the
> CRT, it's just that the new CRT has inlined those particular
> functions.

Hi Phil:

Thanks very much for the above investigation.

>
> Alan I will leave you to integrate this how you see fit as I wouldn't
> know where to start.
>

It turns out we use check_function_exists a lot of places in our build
system, but I don't think any of those have to do with io-related
functions other than the checks for snprintf and _snprintf.  So I have
only changed those two instances (see commit id ac0f09f) to use the
check_symbol_exists form that you found above works for you (and
which also works for me on Linux).

To finish off this topic, please test this latest version of PLplot
for your Visual Studio 2015 platform and assuming that the PLplot
build shows no other check_function_exists failures, then please close
the bug report appropriately.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
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