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 <masahiroy@kernel.org> Acked-by: Randy Dunlap <rdunlap@infradead.org>
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@ -396,35 +396,6 @@ static struct expr *expr_eliminate_yn(struct expr *e)
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return e;
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}
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/*
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* bool FOO!=n => FOO
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*/
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struct expr *expr_trans_bool(struct expr *e)
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{
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if (!e)
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return NULL;
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switch (e->type) {
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case E_AND:
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case E_OR:
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case E_NOT:
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e->left.expr = expr_trans_bool(e->left.expr);
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e->right.expr = expr_trans_bool(e->right.expr);
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break;
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case E_UNEQUAL:
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// FOO!=n -> FOO
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if (e->left.sym->type == S_TRISTATE) {
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if (e->right.sym == &symbol_no) {
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e->type = E_SYMBOL;
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e->right.sym = NULL;
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}
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}
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break;
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default:
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;
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}
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return e;
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}
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/*
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* e1 || e2 -> ?
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*/
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@ -284,7 +284,6 @@ void expr_free(struct expr *e);
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void expr_eliminate_eq(struct expr **ep1, struct expr **ep2);
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int expr_eq(struct expr *e1, struct expr *e2);
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tristate expr_calc_value(struct expr *e);
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struct expr *expr_trans_bool(struct expr *e);
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struct expr *expr_eliminate_dups(struct expr *e);
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struct expr *expr_transform(struct expr *e);
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int expr_contains_symbol(struct expr *dep, struct symbol *sym);
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@ -398,8 +398,6 @@ static void _menu_finalize(struct menu *parent, bool inside_choice)
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dep = expr_transform(dep);
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dep = expr_alloc_and(expr_copy(basedep), dep);
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dep = expr_eliminate_dups(dep);
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if (menu->sym && menu->sym->type != S_TRISTATE)
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dep = expr_trans_bool(dep);
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prop->visible.expr = dep;
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/*
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