bug#19831: 25.0.50; Can't build emacs 25.0.5 with libpng16 support (only libpng15)

[Tory S. Anderson]

I see: 

$ libpng-config --cflags
-I/home/torys/anaconda/include/libpng15

So, I uninstalled libpng and reinstalled it, carefully using the package and 
following the directions from http://www.libpng.org/pub/png/libpng.html
And yet, to my frustration, afterwards I STILL received: 

$ libpng-config --cflags
-I/home/torys/anaconda/include/libpng15

I can't seem to get around this. Any suggestions would be appreciated. 


Eli Zaretskii <eliz@gnu.org> writes:

>> From: torys.anderson@gmail.com (Tory S. Anderson)
>> Date: Tue, 10 Feb 2015 12:57:53 -0500
>> 
>> 
>> I have libpng16 (and 15) installed with dev files; my libpng.so points to 
>> version 16. But emacs 25.0.5 refuses to work with 16. Although the config 
>> log is full of references to lpng16, it seems to choose to load with lib15 
>> (and won't build with png support if I don't make v 15 available). This is 
>> breaking other programs that expect to be using the latest libpng on the 
>> computer.
>
> What does this shell command display:
>
>   libpng-config --cflags
>
> It looks like this is what's responsible for the fact that Emacs
> decides you have libpng15 installed.  So I think the way you installed
> libpng16 is missing the update of libpng-config.