On Wed, Oct 28, 2020 at 2:16 PM Nick Bowler <nbow...@draconx.ca> wrote: > On 2020-10-28, H.J. Lu <hjl.to...@gmail.com> wrote: > > GCC introduced some time ago option -flto=jobserver in order to use the > > GNU Make jobserver when parallelising LTO builds. It is actually a > > similar "recursive make". When doing a recursive make, you need to > > place a '+' character at the beginning of the recipe line in order to > > let GNU Make pass the jobserver file descriptors to the child processes. > > > > Add the --jobserver option to add a '+' character to the recipe line in > > program.am and ltlibrary.am. ... > Surely this needs to be a configure-time option, perhaps combined > with some sort of configure test, since otherwise users won't get > this choice, right? As an automake option the choice made by whomever > prepares the distribution will get baked into distributed Makefile.in > files...
I was going to say something very similar: there shouldn't be an option at all. The decision of whether or not to put + at the beginning of the recipe line should be made _when make is run_, based on whether -flto=jobserver actually appears in $(LDFLAGS) or wherever. > This will break "make -n", won't it? Some sort of test of $(MAKEFLAGS) > is probably required in this command. I concur with this as well. zw
