Re: [PATCH 2/2] kconfig: error on reverse range

[Nicolas Schier]

> As discussed on kconfirm v4 [1], it was decided to move checks directly
> into the kconfig interpreter once where are no findings from kconfirm.

s/where/there/

> This "reverse range" currently has no findings across the tree, so let's
> add the check.
> 
> Currently, if a reverse range is attempted, such as:
> 
>     config EXAMPLE
>         int "Reverse range example"
>         range 2 1
> 
> then the value of the option defaults to its "lower" limit of 2. If the
> option is visible in the frontend, then the user gets trapped in the value
> selection interface, since there is no value that is actually valid for
> the user to set.
> 
> Note that this only checks ranges that use constant values. Statically
> checking ranges using symbols would require SAT solving, or similar.
> 
> Link: https://lore.kernel.org/all/20260904220559.GB2787252@ax162/ [1]
> Assisted-by: LLM
> Signed-off-by: Julian Braha <julianbraha@xxxxxxxxx>
>
> diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
> index 118af2dde722..cc335f6db257 100644
> --- a/scripts/kconfig/menu.c
> +++ b/scripts/kconfig/menu.c
> @@ -274,9 +274,9 @@ static int menu_validate_number(struct symbol *sym, struct symbol *sym2,
>  static int sym_check_prop(struct symbol *sym)
>  {
>  	struct property *prop;
> -	struct symbol *sym2;
> +	struct symbol *sym2, *lower, *upper;
>  	char *use;
> -	int errors = 0;
> +	int errors = 0, numeric_errors = 0;
>  
>  	for (prop = sym->prop; prop; prop = prop->next) {
>  		switch (prop->type) {
> @@ -325,8 +325,22 @@ static int sym_check_prop(struct symbol *sym)
>  			if (sym->type != S_INT && sym->type != S_HEX)
>  				prop_warn(prop, "range is only allowed "
>  						"for int or hex symbols");
> -			errors += menu_validate_number(sym, prop->expr->left.sym, prop);
> -			errors += menu_validate_number(sym, prop->expr->right.sym, prop);
> +			lower = prop->expr->left.sym;
> +			upper = prop->expr->right.sym;
> +			numeric_errors += menu_validate_number(sym, lower, prop);
> +			numeric_errors += menu_validate_number(sym, upper, prop);
> +			errors += numeric_errors;
> +			if (numeric_errors || lower->type != S_UNKNOWN || upper->type != S_UNKNOWN)
> +				break;
> +
> +			if ((sym->type == S_INT &&
> +				strtoll(lower->name, NULL, 10) > strtoll(upper->name, NULL, 10)) ||
> +				(sym->type == S_HEX &&
> +				strtoull(lower->name, NULL, 16) > strtoull(upper->name, NULL, 16))) {
> +				prop_err(prop, "range lower limit '%s' is greater than upper limit '%s'",
> +					lower->name, upper->name);
> +				errors++;
> +			}

Thanks, looks good to me.  I don't like that we do these strto{u,}ll()
conversions everywhere repeated.  But I think it's ok for now.

Tested-by: Nicolas Schier <n.schier@xxxxxxxxx>
Reviewed-by: Nicolas Schier <n.schier@xxxxxxxxx>

-- 
Nicolas