linux-kernel - Re: [PATCH 2/2] kconfig: make 'imply' obey the direct dependency

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Message-ID: <CAMuHMdWUvKXOU1LWZ-Vmb_tTe8b1wHrWFW6dEnENNSs0S7AvWQ@mail.gmail.com>
Date:   Fri, 6 Mar 2020 13:17:15 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Nicolas Pitre <nico@...xnic.net>,
        Ulf Magnusson <ulfalizer@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Michal Marek <michal.lkml@...kovi.net>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH 2/2] kconfig: make 'imply' obey the direct dependency

Hi Yamada-san,

On Mon, Mar 2, 2020 at 7:24 AM Masahiro Yamada <masahiroy@...nel.org> wrote:
> The 'imply' statement may create unmet direct dependency when the
> implied symbol depends on m.
>
> [Test Code]
>
>   config FOO
>           tristate "foo"
>           imply BAZ
>
>   config BAZ
>           tristate "baz"
>           depends on BAR
>
>   config BAR
>           def_tristate m
>
>   config MODULES
>           def_bool y
>           option modules
>
> If you set FOO=y, BAZ is also promoted to y, which results in the
> following .config file:
>
>   CONFIG_FOO=y
>   CONFIG_BAZ=y
>   CONFIG_BAR=m
>   CONFIG_MODULES=y
>
> This does not meet the dependency 'BAZ depends on BAR'.
>
> Unlike 'select', what is worse, Kconfig never shows the
> 'WARNING: unmet direct dependencies detected for ...' for this case.
>
> Because 'imply' is considered to be weaker than 'depends on', Kconfig
> should take the direct dependency into account.
>
> For clarification, describe this case in kconfig-language.rst too.
>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>

This fixes some issue with "imply SND_SOC_WCD934X".
Tested-by: Geert Uytterhoeven <geert@...ux-m68k.org>

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds