On Thu, Sep 28 2017, NeilBrown wrote:
> Hi,
> One of my Makefiles contains
> MAKEFLAGS += -j
>
> Prior to the above commit, this would cause make to run as if I had run
> make -j
>
> Since that commit, it appears to be ignored. If I run
> make -j
> explicitly I get parallel makes, but setting MAKEFLAGS in the Makefile
> doesn't achieve that result.
>
> This usage is still described as supported by make.texi:
>
> The @code{MAKEFLAGS} variable can also be useful if you want to have
> certain options, such as @samp{-k} (@pxref{Options Summary, ,Summary of
> Options}), set each time you run @code{make}. You simply put a value for
> @code{MAKEFLAGS} in your environment. You can also set @code{MAKEFLAGS} in
> a makefile, to specify additional flags that should also be in effect for
> that makefile. (Note that you cannot use @code{MFLAGS} this way. That
> variable is set only for compatibility; @code{make} does not interpret a
> value you set for it in any way.)
I dug into this a bit.
The regression is caused because the 'j' flag now causes arg_job_slots
to be set, rather than setting job_slots directly.
arg_job_slots is conditionally copied into job_slots after the call to
decode_env_switches (STRING_SIZE_TUPLE ("MAKEFLAGS"));
at line 1453, but that is called again at line 1993 and the value set
then (which is when the value from "MAKEFLAGS += -j" in a Makefile takes
effect) is lost.
A possible fix is:
diff --git a/main.c b/main.c
index 226b26b96862..46e28379d687 100644
--- a/main.c
+++ b/main.c
@@ -1995,6 +1995,10 @@ main (int argc, char **argv, char **envp)
decode_env_switches (STRING_SIZE_TUPLE ("MFLAGS"));
#endif
+ if (!jobserver_auth)
+ /* MAKEFLAGS might have changed arg_job_slots */
+ job_slots = arg_job_slots;
+
/* Reset in case the switches changed our mind. */
syncing = (output_sync == OUTPUT_SYNC_LINE
|| output_sync == OUTPUT_SYNC_TARGET);
but that feels like a bit of a hack. I don't know the code well enough
to be sure.
Thanks,
NeilBrown
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