Make snoopy compile on 64-bit Arch Linux with GCC 7.1.1

[xyproto]

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• My submission is passing test suite run (./configure --enable-everything && make tests) - test suite reports zero unexpected failures. One of the tests fails, but I can not test if it already failed before this commit, since it does not compile here.
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Pull request description

This commit makes snoopy compile, but someone must confirm that the functionality is the same.

The error messages I get before this commit are:

  CC       cmdline.lo
cmdline.c: In function ‘snoopy_datasource_cmdline’:
cmdline.c:71:79: error: comparison between pointer and zero character constant [-Werror=pointer-compare]
     for (cmdLineArgCount=0 ; *(snoopy_inputdatastorage->argv+cmdLineArgCount) != '\0' ; cmdLineArgCount++);
                                                                               ^~
cmdline.c:71:30: note: did you mean to dereference the pointer?
     for (cmdLineArgCount=0 ; *(snoopy_inputdatastorage->argv+cmdLineArgCount) != '\0' ; cmdLineArgCount++);
                              ^
cc1: all warnings being treated as errors
make[2]: *** [Makefile:788: cmdline.lo] Error 1

After this commit, snoopy at least compiles.

[bostjan]

Hi @xyproto, thanks for the contribution.

Did you run the test suite locally on arch, did it work?

Arch is rolling-release distro, right? Can you give any point of reference if I would want to replicate the behaviour locally?

[xyproto]

@bostjan Yes, I ran the test suit locally and it did not work, but I don't know if it did not work also before my patch or not. I commented this in the form above.

I guess the easiest way to test this is to run Arch Linux in a virtual machine or as a docker image. If you don't want any manual setup, something like installing Antergos in VirtualBox should work as well.

[lukas227]

We have this problem in Debian as well (see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=853664) now that gcc-7 is default. I am thinking of applying the same patch (except that I'd rather use NULL instead of 0). With the patch, the test suite run after the build passes (except for 4 specific tests which we needed to disable in Debian due to the special environment in which the build is run, see https://sources.debian.net/src/snoopy/2.4.6-1/debian/patches/03_disable-tests.patch/).

[bostjan]

Tests were working the last time I checked. Which ones are failing?

[bostjan]

Looks good. Thanks!

About config.h.in change: I guess I'll start maintaining Snoopy on Ubuntu 18.04 now :)