[bug #63981] suppress "-jN forced in submake" warning with -j1

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?63981>

                 Summary: suppress "-jN forced in submake" warning with -j1
                   Group: make
               Submitter: None
               Submitted: Thu 30 Mar 2023 04:03:07 PM UTC
                Severity: 3 - Normal
              Item Group: Enhancement
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: None
        Operating System: None
           Fixed Release: None
           Triage Status: None


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Follow-up Comments:


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Date: Thu 30 Mar 2023 04:03:07 PM UTC By: Anonymous
In a recursive make model there may be a subdirectory which isn't
parallel-safe. This can happen particularly when building third-party code
which you can't or shouldn't fix. In this case you may want to suppress
parallelism in that sub-make by passing -j1 but this results in a warning. The
warning makes sense for any -j value >1 but not, I think, with -j1. And the
manual seems to agree. It says:

_This warning is generated if a recursive invocation of a make process is
forced to have ‘-jN’ in its argument list (*where N is greater than
one*)._

But even make 4.4.1 prints it with -j1.

Test case:

$ head -50 Makefile one.mk
==> Makefile <==
.PHONY: all
all:
        $(info Building $@ in $(lastword $(MAKEFILE_LIST)))
        $(MAKE) -j1 -f one.mk

==> one.mk <==
.PHONY: all
all:
        $(info Building $@ in $(lastword $(MAKEFILE_LIST)))
        @:

$ make-4.4.1 -j12 --no-print
Building all in Makefile
make-4.4.1 -j1 -f one.mk
make-4.4.1[1]: warning: -j1 forced in submake: resetting jobserver mode.
Building all in one.mk







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