I have committed a Go frontend patch by Than McIntosh that fixes Array_type::do_export to not emit a type conversion, by fetching the constant value and exporting that. This fixes Go issue 30628. Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu. Committed to mainline.
Unfortunately it appears that I cannot attach the patch to this e-mail message, because every attempt to do so causes my e-mail to be blocked by GMail. I have no idea why. So if you want to see the actual diffs, please see https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=269443 . Ian