| Message ID | 20240603161904.1663388-3-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/3] kconfig: doc: fix a typo in the note about 'imply' | expand |
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@kernel.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> 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; > > /*
On Tue, Jun 4, 2024 at 1:19 AM Masahiro Yamada <masahiroy@kernel.org> 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 This is wrong. I meant this: select C if B != n
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; /*
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 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@kernel.org> --- scripts/kconfig/expr.c | 29 ----------------------------- scripts/kconfig/expr.h | 1 - scripts/kconfig/menu.c | 2 -- 3 files changed, 32 deletions(-)