DESTDIR not respected
if configured with --enable-mbc
make[3]: Entering directory '/var/tmp/portage/sci-physics/mbdyn-1.7.3_p20210902/work/mbdyn-51f6082658fe8ba5b85a0edb32fab461aa6855fa/libraries/libmbc'
/bin/sh /var/tmp/portage/sci-physics/mbdyn-1.7.3_p20210902/work/mbdyn-51f6082658fe8ba5b85a0edb32fab461aa6855fa/build/install-sh -d /usr/libexec/mbpy
/bin/mkdir -p '/var/tmp/portage/sci-physics/mbdyn-1.7.3_p20210902/image/usr/include'
/bin/mkdir -p '/var/tmp/portage/sci-physics/mbdyn-1.7.3_p20210902/image/usr/lib64'
/bin/sh ../../libtool --mode=install /usr/lib/portage/pypy3/ebuild-helpers/xattr/install -c libmbc.la _mbc_py.la '/var/tmp/portage/sci-physics/mbdyn-1.7.3_p20210902/image/usr/lib64'
/usr/lib/portage/pypy3/ebuild-helpers/xattr/install -c -m 644 mbc.h mbcxx.h '/var/tmp/portage/sci-physics/mbdyn-1.7.3_p20210902/image/usr/include'
libtool: install: /usr/lib/portage/pypy3/ebuild-helpers/xattr/install -c .libs/libmbc.so.0.0.0 /var/tmp/portage/sci-physics/mbdyn-1.7.3_p20210902/image/usr/lib64/libmbc.so.0.0.0
* ACCESS DENIED: mkdir: /usr/libexec/mbpy
mkdir: cannot create directory ‘/usr/libexec/mbpy’: Permission denied
libtool: install: (cd /var/tmp/portage/sci-physics/mbdyn-1.7.3_p20210902/image/usr/lib64 && { ln -s -f libmbc.so.0.0.0 libmbc.so.0 || { rm -f libmbc.so.0 && ln -s libmbc.so.0.0.0 libmbc.so.0; }; })
* ACCESS DENIED: mkdir: /usr/libexec/mbpy
mkdir: cannot create directory ‘/usr/libexec/mbpy’: Permission denied
libtool: install: (cd /var/tmp/portage/sci-physics/mbdyn-1.7.3_p20210902/image/usr/lib64 && { ln -s -f libmbc.so.0.0.0 libmbc.so || { rm -f libmbc.so && ln -s libmbc.so.0.0.0 libmbc.so; }; })
make[3]: *** [Makefile:931: install-exec-local] Error 1
make[3]: *** Waiting for unfinished jobs....
in gentoo we use a sandbox to avoid installing to the live filesystem, in this case the libraries/libmbc/Makefile.am
isn't respecting DESTDIR