Bug#1006009: qtimageformats-opensource-src: FTBFS on mipsel: test failure

[Dmitry Shachnev <mitya57@debian.org>]

Control: reassign -1 libwebp7 1.2.1-7
Control: affects -1 src:qtimageformats-opensource-src

Hi Sebastian and libwebp maintainers!

On Fri, Feb 18, 2022 at 10:39:23PM +0100, Sebastian Ramacher wrote:
> Source: qtimageformats-opensource-src
> Version: 5.15.2-2
> Severity: serious
> Tags: ftbfs
> Justification: fails to build from source (but built successfully in the past)
> X-Debbugs-Cc: sramacher@debian.org
>
> qtimageformats-opensource-src FTBFS on mipsel:
>
> TIFFReadDirectory: Warning, Sum of Photometric type-related color channels and ExtraSamples doesn't match SamplesPerPixel. Defining non-color channels as ExtraSamples..
> TIFFReadDirectory: Warning, Sum of Photometric type-related color channels and ExtraSamples doesn't match SamplesPerPixel. Defining non-color channels as ExtraSamples..
> PASS   : tst_qtiff::tiffGrayscale()
> FAIL!  : tst_qwebp::writeImage(kollada_noalpha-100) '!reread.isNull()' returned FALSE. ()
>    Loc: [tst_qwebp.cpp(174)]
> PASS   : tst_qwebp::cleanupTestCase()
> Totals: 10 passed, 1 failed, 0 skipped, 0 blacklisted, 632ms
> ********* Finished testing of tst_qwebp *********
>
> See
> https://buildd.debian.org/status/fetch.php?pkg=qtimageformats-opensource-src&arch=mipsel&ver=5.15.2-2%2Bb1&stamp=1645209225&raw=0

It looks to me like a bug in new libwebp version: encoder generates broken
webp files on mipsel.

I can reproduce it without any Qt code by encoding the attached PNG file and
then trying to decode it back:

(sid_mipsel-dchroot)mitya57@eller:~$ cwebp kollada_noalpha.png -lossless -o kollada_noalpha.webp
Saving file 'kollada_noalpha.webp'
File:      kollada_noalpha.png
Dimension: 436 x 160
Output:    37004 bytes (4.24 bpp)
Lossless-ARGB compressed size: 37004 bytes
  * Header size: 636 bytes, image data size: 36342
  * Precision Bits: histogram=3 transform=3 cache=1
(sid_mipsel-dchroot)mitya57@eller:~$ dwebp kollada_noalpha.webp
Decoding of kollada_noalpha.webp failed.
Status: 3(BITSTREAM_ERROR)

I am also attaching the generated broken WEBP file.

--
Dmitry Shachnev

Attachment: kollada_noalpha.png
Description: PNG image

Attachment: kollada_noalpha.webp
Description: Binary data

Attachment: signature.asc
Description: PGP signature