Re: [platform-testers] automake-1.16.92 released

On 2024-07-01 10:21, Zack Weinberg wrote:
> # clue Make that gen-foo also updated foo.h whenever foo.c is new
> foo.h: foo.c
>         @:
> 
> If I had to guess, I would guess that someone thought Make would be
> more likely to skip invoking a shell if the command was actually empty
> rather than ":".  As it happens, GNU Make 4.4.1 appears to recognize
> ":" as a no-op; using strace I see it issue the same number of forks
> for both constructs.  But perhaps older versions of gnumake did not do
> this.  (This is clearly not a portable makefile to begin with, so
> questions of what other implementations do are moot.)

FWIW the POSIX-standard way to define a target rule with no commands it
to follow its prerequisites with a semicolon, for example:

  foo.h : foo.c ;

This is supported by literally every make implementation that I am
aware of, all the way back to the original make from UNIX V7.

Cheers,
  Nick