While working on GIMP 3.0 packaging, I stumbled on:

configure:31882: $PKG_CONFIG --exists --print-errors "libjxl >= 0.6.1"
Package libhwy was not found in the pkg-config search path.
Perhaps you should add the directory containing `libhwy.pc'
to the PKG_CONFIG_PATH environment variable
Package 'libhwy', required by 'libjxl', not found

Please add all the required -dev packages to libjxl-dev dependencies,
so building against libjxl is possible without adding any extra
Build-Deps.

The current version in experimental has the following in its .pc file:

Requires.private: libhwy libbrotlicommon libbrotlienc libbrotlidec lcms2

Thank you!
Jordi

We believe that the bug you reported is fixed in the latest version of
jpeg-xl, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1010856@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Mathieu Malaterre <malat@debian.org> (supplier of updated jpeg-xl package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Mon, 04 Jul 2022 11:54:24 +0200
Source: jpeg-xl
Architecture: source
Version: 0.7.0~git20220704.de6a16a-1
Distribution: experimental
Urgency: medium
Maintainer: Debian PhotoTools Maintainers <pkg-phototools-devel@lists.alioth.debian.org>
Changed-By: Mathieu Malaterre <malat@debian.org>
Closes: 1010856
Changes:
 jpeg-xl (0.7.0~git20220704.de6a16a-1) experimental; urgency=medium
 .
   * d/p/manpages.patch: Add missing command line options
   * New upstream version 0.7.0~git20220408.e6264cd+ds
   * d/patches: Refresh patches
   * d/control: Remove dh-exec since not used anymore
   * d/rules: Set SKCMS bundle option to OFF for consistency
   * d/control: Add dependency to libjxl-testdata
   * d/patches: Add support for testdata in /usr
   * d/patches: Fix installation of cjxl_ng
   * d/control: Properly Implement <!nocheck>
   * d/patches: Remove a failing test
   * d/patches: Add a fix when RPATH is not set
   * d/rules: Make sure to remove by-products from test-suite
   * New upstream version 0.7.0~git20220420.6cce649+ds
   * d/patches: Remove patches applied upstream
   * d/rules: Adapt to latest change for jxlinfo
   * d/control: Bump Std-Vers to 4.6.1 no changes needed
   * d/control: make libjxl-dev depend on required libraries. Closes: #1010856
   * d/control: Make sure to use latest of testdata
   * d/copyright: Adapt to latest upstream changes
   * New upstream version 0.7.0~git20220704.de6a16a
   * d/patches: Refresh patches according to latest upstream
   * d/rules: Only apply no-psabi on armel/armhf
   * d/rules: Remove add_noise to match upstream
Checksums-Sha1:
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 d1d2afce8011bac5402b002381504e047d4d62b6 13916 jpeg-xl_0.7.0~git20220704.de6a16a-1.debian.tar.xz
 93fa49490691c64292adad51053e3d667972c8b3 11080 jpeg-xl_0.7.0~git20220704.de6a16a-1_source.buildinfo
Checksums-Sha256:
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 abcc264b33321e35b462442ecb6947e4eb4027262451745c23cc451ae3b4732e 1115176 jpeg-xl_0.7.0~git20220704.de6a16a.orig.tar.xz
 262e5f192a49a46392b62c65abc8550f1da16ac61519f854d2f94cfaaaf4804e 13916 jpeg-xl_0.7.0~git20220704.de6a16a-1.debian.tar.xz
 5d053c8167d2d6c4fa95d0ca285ca56cf7aba9aa5672455258ef6b04894027a9 11080 jpeg-xl_0.7.0~git20220704.de6a16a-1_source.buildinfo
Files:
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 795f2b09ceefba6b9ae5b21a4d1de7a6 1115176 graphics optional jpeg-xl_0.7.0~git20220704.de6a16a.orig.tar.xz
 b35391d06d12e56d182df7d522285745 13916 graphics optional jpeg-xl_0.7.0~git20220704.de6a16a-1.debian.tar.xz
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