I am bootstrapping GNU a2ps git master[1] with automake 1.16.5. When I do a parallel build (in my case, MAKEFLAGS=-j4), I get build failures sometimes:
$ make all make all-am make[1]: Entering directory '/home/rrt/.local/var/repo/a2ps/src' YACC parsessh.c CC libparse_a-lexssh.o /home/rrt/repo/a2ps/src/ylwrap1077905 lexssh.c:38:11: fatal error: parsessh.h: No such file or directory 38 | #include "parsessh.h" | ^~~~~~~~~~~~ compilation terminated. make[1]: *** [Makefile:1710: libparse_a-lexssh.o] Error 1 make[1]: *** Waiting for unfinished jobs.... parsessh.output is unchanged updating parsessh.h make[1]: Leaving directory '/home/rrt/.local/var/repo/a2ps/src' make: *** [Makefile:1514: all] Error 2 But parsessh.h is listed in BUILT_SOURCES, so it should be built before any other target. [1] git clone https://git.savannah.gnu.org/git/a2ps.git -- https://rrt.sc3d.org