Simple problem, simple fix. One cannot use crossdev's mingw-w64 toolchain to build packages using meson at the moment. The fix is the addition of `*-w64-mingw*) system=windows ;;` in the case statement in _meson_create_cross_file() function (plus maybe a bit of formatting and alignment).
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=f4ea3e88f050277653eef242be707079ca5ad03d commit f4ea3e88f050277653eef242be707079ca5ad03d Author: Mike Gilbert <floppym@gentoo.org> AuthorDate: 2017-11-05 21:52:14 +0000 Commit: Mike Gilbert <floppym@gentoo.org> CommitDate: 2017-11-05 21:56:49 +0000 meson.eclass: set system=windows for mingw cross-compiles Closes: https://bugs.gentoo.org/636654 eclass/meson.eclass | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)