bin/50193: convergent circular rules in make

[dholland%netbsd.org@localhost]

>Number:         50193
>Category:       bin
>Synopsis:       convergent circular rules in make
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Thu Sep 03 07:35:00 +0000 2015
>Originator:     David A. Holland
>Release:        n/a
>Organization:
>Environment:
n/a
>Description:

It would be useful for some process automation tasks (and even some
build tasks) if make supported circular rules that were expected to
converge after some (fixed) number of times around.

e.g. something like

   foo: foo.c foo.h foo.gmon
           $(CC) -pg -O2 -fuse-profile-data=foo.gmon foo.c -o foo.new
	   if diff foo foo.new > /dev/null 2>&1; then mv -f foo.new foo; fi
   foo.gmon: foo
           ./foo
	   mv -f gmon.out foo.gmon
   .CONVERGE(20): foo

where you'd pick 20 or whatever based on your expectation.

This needs further refinement, and I am thinking out loud, but I
wanted to file this somewhere so it doesn't get forgotten.

>How-To-Repeat:
n/a
>Fix:
n/a