zimoun <zimon.toutoune@gmail.com> writes:

> My question is: is it possible to specify 'inputs' only for specific
> 'outputs'?

No, but only because the two concepts are not directly related.

A derivation has inputs, an output doesn't, but it does have references.

Take git as an example.

→ guix build git
/gnu/store/76f7iracvzjqwzxldcdr9055ia1vdgw7-git-2.26.2-credential-netrc
/gnu/store/fmxq1pawy32zw0a0qb371a36lr58rwzf-git-2.26.2-gui
/gnu/store/axbf1db65bk316c44csnf6bgkzb4ilvx-git-2.26.2
/gnu/store/826y3r09kjl0fg1c51xwrlxvjd4kb8ff-git-2.26.2-send-email
/gnu/store/dw4c975zfnvabpzl0sg7n7fv8spdflv6-git-2.26.2-subtree
/gnu/store/sz27ibw6f3icyvwjvhlvqjn2kp2x6mbp-git-2.26.2-svn

→ guix gc --references /gnu/store/sz27ibw6f3icyvwjvhlvqjn2kp2x6mbp-git-2.26.2-svn
/gnu/store/0bnp4bh1cid0xb415n6h4iyl52cmwpgd-perl-term-readkey-2.38
/gnu/store/8zvc5mvk0xm3ygrxsgpyy5ilxb5rzjry-perl-5.30.2
/gnu/store/axbf1db65bk316c44csnf6bgkzb4ilvx-git-2.26.2
/gnu/store/fvhj74pghapbjvsvj27skvkra1by1965-bash-minimal-5.0.16
/gnu/store/sz27ibw6f3icyvwjvhlvqjn2kp2x6mbp-git-2.26.2-svn
/gnu/store/wn07ns1i8pqjfz92xkbicm5azg5jx2lc-subversion-1.14.0

→ guix gc --references /gnu/store/axbf1db65bk316c44csnf6bgkzb4ilvx-git-2.26.2
/gnu/store/01b4w3m6mp55y531kyi1g8shh722kwqm-gcc-7.5.0-lib
/gnu/store/09a5iq080g9b641jyl363dr5jkkvnhcn-python-3.8.2
/gnu/store/85lvkhmvr3a75j6rl4y7xj67qdnb9ssr-perl-cgi-4.47
/gnu/store/8zvc5mvk0xm3ygrxsgpyy5ilxb5rzjry-perl-5.30.2
/gnu/store/axbf1db65bk316c44csnf6bgkzb4ilvx-git-2.26.2
/gnu/store/d48261l1a5xvyibj5vlnravwlkwcil8c-perl-html-parser-3.72
/gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31
/gnu/store/fvhj74pghapbjvsvj27skvkra1by1965-bash-minimal-5.0.16
/gnu/store/hcxpkksmbql6s4al8yy2myr25kh4cic0-openssl-1.1.1g
/gnu/store/imh5xxqw10dql4crlngbbjh4r24raf4j-expat-2.2.9
/gnu/store/qvahafxrr2mcl4anjxdkkprrvd4k0xjj-pcre2-10.34
/gnu/store/rykm237xkmq7rl1p0nwass01p090p88x-zlib-1.2.11
/gnu/store/wlz0dsvc00s59cbjlyb04v9rvxiprqsz-curl-7.69.1


Looking at different outputs, the references are different. If you're
just using the "out" output, then you don't need subversion in your
store, but if you're using the "svn" output, then you do, as that output
references an output for subversion.

The references for an output isn't something specified, but something
decided by what references that output actually contains.

Hope that helps,

Chris