Re: '... | Avoiding implicit rule recursion for rule '%/dir: %'. | ...'

[Dmitry Goncharov]

On Tue, Nov 5, 2024 at 8:55 AM WaitronCharm via Bug reports and
discussion for GNU make <bug-make@gnu.org> wrote:
> Is there any design rationale why 'make' does not like applying the same 
> pattern rule more than once for the same target?

Maybe the authors had some other reason, but the only reason i can see
today for implicit rules (other than match-anything rules) is
avoidance of infinite recursion in cases like the following

all: hello.tsk
%.tsk: %.o; $(info hello.tsk)
%.o: %.c %.tsk; $(info hello.c)


> I am sure there are legitimate cases where recursively (but not infinitely) 
> applying pattern rules should be useful.

How do you teach make to allow some, but not infinite recursion?

> Could this restriction be relaxed with an extra command line option?

A command line switch may not be the best option here. No user will
know to specify the switch. A better option is a special target. A
special target is mentioned in the makefile and relieves the user from
knowing or specifying a switch.

> Or, this would create complications (internal logic, graph structures etc.)?

i don't see complications, as long as the behavior of match-anything
rules stays intact.

regards, Dmitry