(address . bug-guix@gnu.org)
861qv8elr5.fsf@gmail.com
Hi,
Following discussions [1,2], this report tracks issue when
cross-compiling the package ’azpainter’, if it would make sense to
cross-compile such package. ;-)
For the record, upstream [3] does not have a clear bug tracker where to
report the issue.
Cheers,
simon
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Subject: [bug#55541] [PATCH] gnu: Add azpainter.
From: Maxime Devos <maximedevos@telenet.be>
Date: Fri, 20 May 2022 18:00:22 +0200
Tobias Kortkamp schreef op vr 20-05-2022 om 13:18 [+0200]:
Toggle quote (11 lines)
> + (build-system gnu-build-system) ;actually a home grown build system
> + (arguments
> + (list #:tests? #f
> + #:phases
> + #~(modify-phases %standard-phases
> + (replace 'configure
> + (lambda _
> + (invoke "./configure"
> + (string-append "--prefix="
> + #$output))))
As-is, this home-grown build system is broken when cross-compiling:
* When cross-compiling, TARGET-gcc needs to be used instead of gcc.
Maybe do (setenv "CC" #$(cc-for-target)) first?
* Likewise, TARGET-pkg-config instead of pkg-config (not 100% sure)
* It tries to run binaries during ./configure. When cross-compiling,
./conftest will always fail (unless using emulation) and hence
always detect ‘little endian’ but this is incorrect when
cross-compiling for big-endian architectures.
(Needs some fixes or work-arounds.) You can test with "guix build
azpainter --target=aarch64-linux-gnu" or such.
Also, some other problems. From mlk_studio.c
int mFILEreadBE32(FILE *fp,void *buf)
{
uint8_t v[4];
if(fread(v, 1, 4, fp) < 4)
return 1;
else
{
*((uint32_t *)buf) = ((uint32_t)v[0] << 24) | (v[1] <<
16) | (v[2] << 8) | v[3];
return 0;
}
}
looks like a potential strict-aliasing violation to me, resulting in
undefined behaviour -- what if buf is a pointer to an array of, say,
doubles? Also a potential alignment problem, though maybe it's only
called for sufficiently aligned 'buf'. The strict-aliasing problem
can be worked around with -fno-strict-aliasing or maybe just -fno-ipa-
strict-aliasing , though I don't know if that's sufficient.
Greetings,
Maxime.
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