From 77a92660d8fe8d29503fae768d9f5eb529c88b36 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 4 Jun 2024 01:19:04 +0900 Subject: kconfig: remove wrong expr_trans_bool() 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 output is incorrect because CONFIG_C=y is expected. Documentation/kbuild/kconfig-language.rst clearly explains the function of the '!=' operator: If the values of both symbols are equal, it returns 'n', otherwise 'y'. Therefore, the statement: select C if B != n should be equivalent to: select C if y Or, more simply: select C Hence, the symbol C should be selected by the value of A, which is 'y'. However, expr_trans_bool() wrongly transforms it to: select C if B Therefore, the symbol C is selected by (A && B), which is '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 Acked-by: Randy Dunlap --- scripts/kconfig/expr.h | 1 - 1 file changed, 1 deletion(-) (limited to 'scripts/kconfig/expr.h') 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); -- cgit