Re: makefile rules

[Paul Eggert]

On 12/21/21 11:50, Jim Meyering wrote:
> One must delete $@ and the potential $@-t temporary file in any rule
> that creates a generated file and marks it (as I prefer always to do) as
> read-only by using chmod to subtract write permissions.
>
> Otherwise, the attempt to redirect to $@-t (when it is read-only) will fail.

Gnulib isn't doing a chmod -w so that shouldn't be an issue here.

Quite possibly Gnulib's 'rm -f $@' got copied from earlier recipes that 
did 'chmod -w' for the reason you mention.

If we were going to do a 'chmod -w' then we could do "create $@-t; chmod 
a-w $@-t; mv -f $@-t $@' which (though not perfect) would be good 
enough. Perhaps we didn't do that long ago in coreutils etc. because 'mv 
-f' wasn't universal way back then? It's safe to assume 'mv -f' 
nowadays, though.

My preference is to not do the chmod -w, though, as I've found it to be 
more of a hassle than a help. Even though 'configure' creates a bunch of 
files that could be read-only, it's nice to be able to edit them easily 
while debugging a 'make' gone wrong. Similarly for the .h files that the 
Gnulib recipes generate.