On netbsd 9.3, the following configure options will let gmake build to completion.

  > ./configure --without-all --without-x --without-compress-install --localstatedir=/var --disable-autodepend --prefix=/path/to/emacs-29.0.92 --build=x86_64--netbsd --host=x86_64--netbsd --enable-option-checking=yes --without-pop --without-mailutils 'CFLAGS=-O2 -D_FORTIFY_SOURCE=2 -I/usr/include' 'CPPFLAGS=-DTERMINFO -I/usr/include' 'LDFLAGS=-L/usr/lib -Wl,-R/usr/lib -Wl,-R/usr/pkg/lib'

The following steps in the build process fail after unpacking the source distribution files.

 > $ sh ./autogen.sh
 > $ ./configure --without-x
 > $ gmake
 >
 > ...
 >
 > ***
 > *** "make all" failed with exit status 2.
 > ***
 > *** You could try to:
 > *** - run "make bootstrap", which might fix the problem
 > *** - run "make V=1", which displays the full commands invoked by make,
 > ***   to further investigate the problem
 > ***
 > gmake[1]: *** [Makefile:414: advice-on-failure] Error 2
 > gmake[1]: Leaving directory '/usr/X/23/src/emacs/emacs-29.0.92'
 > gmake: *** [Makefile:370: all] Error 2
 > 
 > $ gmake bootstrap
 >
 > ...
 > 
 > ***
 > *** "make bootstrap" failed with exit status 2.
 > ***
 > *** You could try to:
 > *** - run "make extraclean" and run "make" again (or, equivalently, run
 > ***   "make bootstrap configure=default"), to rebuild Emacs with the
 > ***   default configuration options, which might fix the problem
 > *** - run "git clean -fdx" and run "make bootstrap" again, which might
 > ***   fix the problem if "make bootstrap configure=default" did not
 > ***   !BEWARE! "git clean -fdx" deletes all files that are not under
 > ***   !BEWARE! version control, which means that all changes to such
 > ***   !BEWARE! files will be lost and cannot be restored later
 > *** - run "make V=1", which displays the full commands invoked by make,
 > ***   to further investigate the problem
 > *** - report the problem and ask for help by sending an email to
 > ***   bug-gnu-emacs@gnu.org, mentioning at least the build error
 > ***   message, the platform, and the repository revision displayed by
 > ***   "git rev-parse HEAD"
 > ***
 > gmake[1]: *** [Makefile:414: advice-on-failure] Error 2
 > gmake[1]: Leaving directory '/usr/X/23/src/emacs/emacs-29.0.92'
 > gmake: *** [Makefile:1246: bootstrap] Error 2