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Message-ID: <874f0d588c3f96e96a3e2971eaa43b070ba4172e.camel@gnu.org>
Subject: Re: [PATCH v2] Makerules: fix MAKEFLAGS assignment for upcoming
 make-4.4 [BZ# 29564]
From: Paul Smith <psmith@gnu.org>
Reply-To: psmith@gnu.org
To: Sergei Trofimovich <slyich@gmail.com>, libc-alpha@sourceware.org
Cc: Siddhesh Poyarekar <siddhesh@gotplt.org>
Date: Mon, 12 Sep 2022 18:47:11 -0400
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References: <b36fd227-a84d-32a4-5306-a0b288e64950@gotplt.org>
	 <20220912212711.2819763-1-slyich@gmail.com>
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On Mon, 2022-09-12 at 22:27 +0100, Sergei Trofimovich wrote:
> +ifeq ($(findstring s, $(filter-out --% , $(MAKEFLAGS))),)

A more reliable, and guaranteed correct, way to do this is:

  ifeq ($(findstring s,$(firstword -$(MAKEFLAGS)),)

GNU make guarantees that all options which can possibly be represented
as single-letter options will always appear in the first word of
MAKEFLAGS (even if the user used the long option on make's command
line).

It also guarantees that there will be a space before any non-short
options, including if there are no short options given.  In that case
"-$(MAKEFLAGS)" would expand to "- --shuffle=3Drandom" (for example) and
firstword would give you just "-".

The filter-out is not as reliable, as it could be possible, someday, to
not filter out something and match incorrectly.