Re: [PATCH] Makefile: ASCII-sort += lists

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Peff,

On Thu, 8 Oct 2020, Jeff King wrote:

> On Thu, Oct 08, 2020 at 12:06:47PM +0200, Johannes Schindelin wrote:
>
> > My little script also finds this:
> >
> > -- snip --
> > @@ -1231,8 +1231,8 @@ space := $(empty) $(empty)
> >
> >  ifdef SANITIZE
> >  SANITIZERS := $(foreach flag,$(subst $(comma),$(space),$(SANITIZE)),$(flag))
> > -BASIC_CFLAGS += -fsanitize=$(SANITIZE) -fno-sanitize-recover=$(SANITIZE)
> >  BASIC_CFLAGS += -fno-omit-frame-pointer
> > +BASIC_CFLAGS += -fsanitize=$(SANITIZE) -fno-sanitize-recover=$(SANITIZE)
> >  ifneq ($(filter undefined,$(SANITIZERS)),)
> >  BASIC_CFLAGS += -DSHA1DC_FORCE_ALIGNED_ACCESS
> >  endif
> > -- snap --
> >
> > I am not _so_ sure that we want to order `BASIC_CFLAGS`, but then, it does
> > not hurt, does it?
>
> I agree it would not be wrong to reorder here from the compiler's
> perspective, but:
>
>   - the current ordering is not arbitrary; the intent was to show that
>     we are enabling -fsanitize, and then follow it up with any other
>     related options (first any that apply to all sanitizers, of which
>     there is only one, and then any sanitizer-specific ones). The patch
>     above splits that logic apart.
>
>   - I'd worry that there are cases in which order _does_ matter to the
>     compiler. I'm not sure if anything that goes in CFLAGS might
>     qualify, but certainly order can matter for other parts of the
>     command-line (e.g., static library order).
>
>     So it might be setting us up for confusion later.

Fair enough. It's easy to exclude `.*_CFLAGS` via a negative look-behind:

	$key = '';
	@to_sort = ();
	while (<>) {
		if ($#to_sort >= 0) {
			if (/^$key \+=/) {
				push @to_sort, $_;
				next;
			}
			print join('', sort @to_sort);
			@to_sort = ();
		}
		if (/^(\S+(?<!_CFLAGS)) \+=/) {
			$key = $1;
			push @to_sort, $_;
		} else {
			print $_;
		}
	}

	if ($#to_sort >= 0) {
		print join('', sort @to_sort);
	}

Ciao,
Dscho