bug#47569: ‘qt-build-system’ retains too many references via wrappers

[Maxim Cournoyer]

Hi Ludovic!

Ludovic Courtès <ludo@gnu.org> writes:

> I just noticed this:
>
> $ guix size ktouch | tail -1
> total: 1752.4 MiB
>
>
> Sounds a lot for a touch typing tutor.
>
> Turns out ktouch references all its build-time dependencies: gcc,
> glibc:static, binutils, findutils, everything.  It comes from the
> wrapper:
>
> $ grep -r s3dcqzwqaakv1yx37by9chksdbkgih17  
> /gnu/store/w8i63ghrq64r7f1nxzw50b0j32f2n8v1-ktouch-20.12.1
> /gnu/store/w8i63ghrq64r7f1nxzw50b0j32f2n8v1-ktouch-20.12.1/bin/ktouch:export 
> XDG_DATA_DIRS="/gnu/store/w8i63ghrq64r7f1nxzw50b0j32f2n8v1-ktouch-20.12.1/share:/gnu/store/ah4az84vjkrssdws7ydvdk1f1mcs70i6-cmake-minimal-3.16.5/share:/gnu/store/3x63j4ndhbzkjwr6mhnp4h86r550gs7q-extra-cmake-modules-5.70.0/share:/gnu/store/qcqghpj3550p94pyqwqmwyd3nqcwflpq-kdoctools-5.70.0/share:/gnu/store/krpyb0zi700dcrg9cc8932w4v0qivdg9-pkg-config-0.29.2/share:/gnu/store/v6f44zccwh9z5zk3pjlywjybbi8n2hjh-tar-1.32/share:/gnu/store/ncydgq2znms5n1d2k5yqshhf58nsixwv-gzip-1.10/share:/gnu/store/i8h2pcxqdq07ijm3ibkka8f4smn1w48v-bzip2-1.0.8/share:/gnu/store/9860f1abqj8wjjnwl8a9v54pdcc3bhgf-xz-5.2.4/share:/gnu/store/60g7r3l01fd7c58yjbm6krgcwj1jkpwg-file-5.38/share:/gnu/store/n4n560pfvvw50a9369axw5vj5rrqfj1n-diffutils-3.7/share:/gnu/store/cd5qf3kcnlq35p9k392pjdpdzpsnds70-patch-2.7.6/share:/gnu/store/hic7snhayfl7m6cpfqqr73nmm19bpqkg-findutils-4.7.0/share:/gnu/store/swqdvwri9dbv6zssg6v0by7l05hd6wxp-gawk-5.0.1/share:/gnu/store/ishk7fswcs4gkwcp8mh788z4mvvl9bxh-sed-4.8/share:/gnu/store/bhs4rj58v8j1narb2454raan2ps38xd8-grep-3.4/share:/gnu/store/57xj5gcy1jbl9ai2lnrqnpr0dald9i65-coreutils-8.32/share:/gnu/store/hm40bxnv8jxmbc1lpb7zfimii4xm9m81-make-4.3/share:/gnu/store/pwcp239kjf7lnj5i4lkdzcfcxwcfyk72-bash-minimal-5.0.16/share:/gnu/store/m1z7cdbqsqyp9xnjw5cvlb4a7gkcg3m4-binutils-2.34/share:/gnu/store/rn75fm7adgx3pw5j8pg3bczfqq1y17lk-gcc-7.5.0/share:/gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31/share:/gnu/store/s3dcqzwqaakv1yx37by9chksdbkgih17-glibc-2.31-static/share:/gnu/store/nnri2x0mdfm2y2ci0p5jhlf6xkdsf6i6-kcmutils-5.70.0/share:/gnu/store/ybh1br5ghs1brnwvacfj04jx3203m87p-kcompletion-5.70.0/share:/gnu/store/bnfcann370ad38g7v4pzgklmizk69f7j-kconfig-5.70.0/share:/gnu/store/4w9v0jnx74n542v11ikzxbf352xqrpwy-kconfigwidgets-5.70.0/share:/gnu/store/9nr52vkhj99g4mx1rr349wwsm2aflnv4-kcoreaddons-5.70.0/share:/gnu/store/9ln7cv5s813nf4ny5l56qadq0vnkx5g0-kdeclarative-5.70.0/share:/gnu/store/fg8npcm84k5bii5jpmdypqdwq10k5xrf-ki18n-5.70.0/share:/gnu/store/0b7xb35ihp5h5qzfcdymzi7yn5lngsgf-kiconthemes-5.70.0/share:/gnu/store/gdch1j5vjjzzx9qq29zca2w83h8nz9rj-kitemviews-5.70.0/share:/gnu/store/q8wrlw1g0m35syx5sr3hq44sx6fsxicj-kqtquickcharts-20.04.1/share:/gnu/store/xhcgpv14llkcdcdn39vrm12mbl4b4y07-ktextwidgets-5.70.0/share:/gnu/store/f4ibdx1ldiifdjbpyh75py4q8i24b05w-kwidgetsaddons-5.70.0/share:/gnu/store/x27qq3i8c3vifrj1q5y9p8840k5dvk40-kwindowsystem-5.70.0/share:/gnu/store/ybdzlpnswajsq1acp3l768h21bvzif16-kxmlgui-5.70.0/share:/gnu/store/3x6y8kpbwjmzpndjfhdbn654g7dm85cp-libxcb-1.14/share:/gnu/store/c7vrkq864hsxfvll74wlrxv71arkcd5q-libxkbfile-1.1.0/share:/gnu/store/sbf77k7xzwhkx4ygqjzgkviz9vy4qhf6-qtbase-5.15.2/share:/gnu/store/k6kk02q27nbymwajkvzhlil8c7sym74k-qtdeclarative-5.15.2/share:/gnu/store/hpirydj1mlmhj199z1ng3yn9sb0f1jc1-qtgraphicaleffects-5.15.2/share:/gnu/store/8165pcgy2d1l30vipkv5qz40nkg9qdp3-qtquickcontrols2-5.15.2/share:/gnu/store/63g70yiyvz08v16hdxsnj3c2pqdq9bm0-qtx11extras-5.15.2/share:/gnu/store/9hpw67pf9px9zx75nb8bm21pc0gqwyx9-qtxmlpatterns-5.15.2/share:/gnu/store/gfapkk5c6hvl1d94m4sqnhn7f9l5gqyh-linux-libre-headers-5.4.20/share:/gnu/store/lfizifxrrbmb9dd1wdm5yy7rlqp7mmfp-kservice-5.70.0/share:/gnu/store/yqaafdggah0hac4n6dkw69ib94v03w69-kcodecs-5.70.0/share:/gnu/store/1syzh2ky8qgxzg59g0g97pqn1gb6xm1r-kauth-5.70.0/share:/gnu/store/s7a55hh8gd8r9dr6m04sqxg5kgngnqcj-kpackage-5.70.0/share:/gnu/store/cizh7vg0w09izkv07pxdv8csir8p4sdd-python-3.8.2/share:/gnu/store/n9wx4dp68bfsw9bb1bwmklzl34ggrmgm-gettext-minimal-0.20.1/share:/gnu/store/rqsn0is9frgi7jz1633l4ipa07xfgsbx-sonnet-5.70.0/share:/gnu/store/6cdl970wcv4jhvpgbh8sdj54a5gwhmwj-libxdmcp-1.1.3/share:/gnu/store/h7sy4hr7arjknbyy1aq0xwv6fksnzw9n-libxau-1.0.9/share:/gnu/store/klk98l8czl05lvanrr7xl7a9hksac4ak-libpthread-stubs-0.4/share:/gnu/store/k30a2pgmc6b3ifmq3rn0dr5ng9gr8w81-which-2.21/share:/gnu/store/14qgm67plbh8d3m6lc87b9j6s9296vwn-mesa-20.2.4/share:/gnu/store/wxl57nkbqgamfp73b7v62kk3f1hiv0cz-xorgproto-2019.2/share:/gnu/store/qv7x7pz7gi724lkdz8049mjhy1ryg511-libxxf86vm-1.1.4/share:/gnu/store/jwga98k68l0h5c45jx7z4jdjzhfc34vm-libxshmfence-1.3/share:/gnu/store/1v6vap6jaf3hf4ypjx261k44xmc48drc-libxfixes-5.0.3/share:/gnu/store/b67b0a5vda7pv7yqyjjb9736s96hhybi-libxdamage-1.1.5/share:/gnu/store/rwkqxykm91a75w9afhb41saj0dmf30hw-libx11-1.6.12/share:/gnu/store/kx58xc3hxa9b0mp1hl7pzz43bl7gh18h-libdrm-2.4.103/share:/gnu/store/lc8irxnwazq340ygkbqh0ask446jzy9k-util-macros-1.19.2/share:/gnu/store/3rmazp46f6g8w9qs8n3w7qcg8hhs1lig-libxext-1.3.4/share"
>
> This is bad for the closure size and probably not good for application
> startup time either.

Oh!  Good finding!  That probably explains why my experiments producing
a guix pack for jami-qt was yielding an archive that'd decompress to 2.7
GiB!

> The problem seems that ‘variables-for-wrapping’ in qt-build-system.scm
> is too naive: it collects in XDG_DATA_DIRS all the /share directories.
> Conversely, ‘data-directories’ in glib-or-gtk-build-system.scm is a bit
> more subtle, keeping only meaningful share/ directories.
>
> I think qt-build-system.scm should copy that strategy.
>
> Thoughts?

I'm not sure why a wrapper is needed in the first place; these
environment variables are honored by qtbase and defined as search path
specifications.  It seems if we were to fix '22138 important Search
paths of dependencies are not honored' we might not have to wrap at all,
unless we really want to be able to run things outside of a profile
(directly from the store) -- which is a nice property, but comes at the
cost of wrappers ugliness (e.g., running 'gdb --args sh
/path/to/wrapper', then having to load the symbols with 'file
/path/to/.the-binary-real; or that wrapper's name appearing in manpages
or other places).

But for the short term, perhaps it's best to copy that strategy?

Thanks for the report!

Maxim