On 6/3/24 9:19 AM, Masahiro Yamada wrote:
> expr_trans_bool() performs an incorrect transformation.
>
> [Test Code]
>
> config MODULES
> def_bool y
> modules
>
> config A
> def_bool y
> select C if B != n
>
> config B
> def_tristate m
>
> config C
> tristate
>
> [Result]
>
> CONFIG_MODULES=y
> CONFIG_A=y
> CONFIG_B=m
> CONFIG_C=m
>
> This result is incorrect because CONFIG_C=y is expected.
>
> Documentation/kbuild/kconfig-language.rst clearly explains the function
> of the '!=' operator:
>
> (3) If the values of both symbols are equal, it returns 'n',
> otherwise 'y'.
>
> Therefore, the statement:
>
> select C if A != n
>
> should be equivalent to:
>
> select C if y
>
> Hence, the symbol C should be selected by 'y' instead of 'm'.
>
> The comment block of expr_trans_bool() correctly explains its intention:
>
> * bool FOO!=n => FOO
> ^^^^
>
> If FOO is bool, FOO!=n can be simplified into FOO. This is correct.
>
> However, the actual code performs this transformation when FOO is
> tristate.
>
> if (e->left.sym->type == S_TRISTATE) {
> ^^^^^^^^^^
>
> While, it can be fixed to S_BOOLEAN, there is no point in doing so
While it can
> because expr_tranform() already transforms FOO!=n to FOO when FOO is
> bool. (see the "case E_UNEQUAL" part)
>
> expr_trans_bool() is wrong and unnecessary.
>
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Thanks.
> ---
>
> scripts/kconfig/expr.c | 29 -----------------------------
> scripts/kconfig/expr.h | 1 -
> scripts/kconfig/menu.c | 2 --
> 3 files changed, 32 deletions(-)
>
> diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
> index 4d95fce5f9a7..fcc190b67b6f 100644
> --- a/scripts/kconfig/expr.c
> +++ b/scripts/kconfig/expr.c
> @@ -396,35 +396,6 @@ static struct expr *expr_eliminate_yn(struct expr *e)
> return e;
> }
>
> -/*
> - * bool FOO!=n => FOO
> - */
> -struct expr *expr_trans_bool(struct expr *e)
> -{
> - if (!e)
> - return NULL;
> - switch (e->type) {
> - case E_AND:
> - case E_OR:
> - case E_NOT:
> - e->left.expr = expr_trans_bool(e->left.expr);
> - e->right.expr = expr_trans_bool(e->right.expr);
> - break;
> - case E_UNEQUAL:
> - // FOO!=n -> FOO
> - if (e->left.sym->type == S_TRISTATE) {
> - if (e->right.sym == &symbol_no) {
> - e->type = E_SYMBOL;
> - e->right.sym = NULL;
> - }
> - }
> - break;
> - default:
> - ;
> - }
> - return e;
> -}
> -
> /*
> * e1 || e2 -> ?
> */
> diff --git a/scripts/kconfig/expr.h b/scripts/kconfig/expr.h
> index fa50fc45622e..7c0c242318bc 100644
> --- a/scripts/kconfig/expr.h
> +++ b/scripts/kconfig/expr.h
> @@ -284,7 +284,6 @@ void expr_free(struct expr *e);
> void expr_eliminate_eq(struct expr **ep1, struct expr **ep2);
> int expr_eq(struct expr *e1, struct expr *e2);
> tristate expr_calc_value(struct expr *e);
> -struct expr *expr_trans_bool(struct expr *e);
> struct expr *expr_eliminate_dups(struct expr *e);
> struct expr *expr_transform(struct expr *e);
> int expr_contains_symbol(struct expr *dep, struct symbol *sym);
> diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
> index 53151c5a6028..eef9b63cdf11 100644
> --- a/scripts/kconfig/menu.c
> +++ b/scripts/kconfig/menu.c
> @@ -398,8 +398,6 @@ static void _menu_finalize(struct menu *parent, bool inside_choice)
> dep = expr_transform(dep);
> dep = expr_alloc_and(expr_copy(basedep), dep);
> dep = expr_eliminate_dups(dep);
> - if (menu->sym && menu->sym->type != S_TRISTATE)
> - dep = expr_trans_bool(dep);
> prop->visible.expr = dep;
>
> /*
--
#Randy
https://people.kernel.org/tglx/notes-about-netiquette
https://subspace.kernel.org/etiquette.html
