In /usr/portage/app-misc/gcstar/gcstar-1.7.0.ebuild, SRC_URI="http://download.gna.org/gcstar/${P}.tar.gz" is offline due to Gentoo bug #606784 (GNA! shutdown). The homepage at http://www.gcstar.org/ is still up, but most hyperlinks on the website are now broken... This bug might also obsolete #606784 (version bump request).
Sorry, the first bug report number is wrong: Should be bug #612500 And now I cannot edit the description anymore.
http://www.gcstar.org/ is listed for debian found with https://repology.org/metapackage/gcstar/versions
the repository moved to https://gitlab.com/Kerenoc/GCstar see: http://forums.gcstar.org/viewtopic.php?pid=29049#p29049
@Alexandre You did not work on this package since a very long time and there was no reaction on this ticket. Was it correct to assign the ticket to you?
Fixed by commit 114177d63df112e931fcb8dc5d674466152009ff (SRC_URI changed to dev.gentoo.org) I must apologize for the very long delay in addressing this; I have had almost no time for Gentoo for several months.