Re: Finding second route through rules

[Steven Simpson]

Hi!

Did this slip under the radar?

Thanks!

On 09/12/15 17:25, Steven Simpson wrote:
> Just noticed a change in behaviour between 3.81 and 4.1:
>
> %.foo: %.bar
>     @echo from bar
>
> %.foo: %.baz
>     @echo from baz
>
> %.baz: %.qux
>     @echo from qux
>
> %.bar: %.quux
>     @echo from quux
>
> gwonk: a.bar
>
>
> So there is a route from a.quux -> a.bar -> a.foo, and from a.qux -> 
> a.baz -> a.foo.  The first is preferred, as implied by the ordering of 
> the first two rules, AIUI.
>
> Create a.qux, and ensure no other a.* files exist, so the second route 
> ought to be chosen.  Then [make a.foo].
>
> $ ls
> a.qux  Makefile
> $ make a.foo
> from qux
> from baz
> $ make -v
> GNU Make 3.81
> Copyright (C) 2006  Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.
> There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
> PARTICULAR PURPOSE.
>
> This program built for x86_64-pc-linux-gnu
>
>
> So Make has chosen the second route, because the first is incomplete.
>
>
>
> $ ls
> a.qux  Makefile
> $ make a.foo
> make: *** No rule to make target 'a.bar', needed by 'a.foo'. Stop.
> $ make -v
> GNU Make 4.1
> Built for x86_64-unknown-linux-gnu
> Copyright (C) 1988-2014 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or 
> later<http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.
>
>
> It seems that Make 4.1 is fixated on the first route, just because the 
> intermediate step a.bar is mentioned as a prerequisite. Disable the 
> gwonk line, and it's fine again.
>
> Just tried on the latest in git, and it is there too.
>
> Is this intended?