On Mon, 2 Mar 2020, Masahiro Yamada 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@xxxxxxxxxx>
Acked-by: Nicolas Pitre <nico@xxxxxxxxxxx>
> ---
>
> Documentation/kbuild/kconfig-language.rst | 7 +++++--
> scripts/kconfig/symbol.c | 4 +++-
> 2 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst
> index d4d988aea679..68719e78ff85 100644
> --- a/Documentation/kbuild/kconfig-language.rst
> +++ b/Documentation/kbuild/kconfig-language.rst
> @@ -159,11 +159,11 @@ applicable everywhere (see syntax).
> Given the following example::
>
> config FOO
> - tristate
> + tristate "foo"
> imply BAZ
>
> config BAZ
> - tristate
> + tristate "baz"
> depends on BAR
>
> The following values are possible:
> @@ -174,6 +174,9 @@ applicable everywhere (see syntax).
> n y n N/m/y
> m y m M/y/n
> y y y Y/m/n
> + n m n N/m
> + m m m M/n
> + y m n M/n
> y n * N
> === === ============= ==============
>
> diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
> index b101ef3c377a..3dc81397d003 100644
> --- a/scripts/kconfig/symbol.c
> +++ b/scripts/kconfig/symbol.c
> @@ -221,7 +221,7 @@ static void sym_calc_visibility(struct symbol *sym)
> sym_set_changed(sym);
> }
> tri = no;
> - if (sym->implied.expr && sym->dir_dep.tri != no)
> + if (sym->implied.expr)
> tri = expr_calc_value(sym->implied.expr);
> if (tri == mod && sym_get_type(sym) == S_BOOLEAN)
> tri = yes;
> @@ -394,6 +394,8 @@ void sym_calc_value(struct symbol *sym)
> if (sym->implied.tri != no) {
> sym->flags |= SYMBOL_WRITE;
> newval.tri = EXPR_OR(newval.tri, sym->implied.tri);
> + newval.tri = EXPR_AND(newval.tri,
> + sym->dir_dep.tri);
> }
> }
> calc_newval:
> --
> 2.17.1
>
>
