bug#55025: Automake should allow one to enable POSIX make behavior

[Nick Bowler]

On 14/01/2023, Mike Frysinger <vapier@gentoo.org> wrote:
[...]
>> I tried several other implementations and they follow the POSIX
>> behaviour by default, adding -e only when errors are not suppressed.
>
> this is exactly my point.  if i'm developing a project with automake
> and i'm using gnu make, i can easily produce bad code that is not
> portable.  but the insidious part is that it doesn't fail for me, it
> fails for my users who are not using gnu make, but using a
> POSIX-compliant implementation that respects the `set -e` behavior.

But as I demonstrated, adding .POSIX doesn't actually make GNU make
work the same as these "POSIX-by-default" implementations.  It just
gives it a different, GNU-specific behaviour, since GNU make apparently
enables -e regardless of whether or not errors are suppressed.

Does changing the behaviour in this way really improve anything for a
maintainer that is only testing with GNU make?

Without putting .POSIX in the Makefile, GNU is at least consistent with
NetBSD here (which never uses -e) and probably also other modern BSD
derivatives, as I think many have these days adopted NetBSD make.

Cheers,
  Nick