kconfig: fix return value of do_error_if()

$(error-if,...) is expanded to an empty string. Currently, it relies on
eval_clause() returning xstrdup("") when all attempts for expansion fail,
but the correct implementation is to make do_error_if() return xstrdup("").

Fixes: 1d6272e6fe43 ("kconfig: add 'info', 'warning-if', and 'error-if' built-in functions")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

diff --git a/scripts/kconfig/preprocess.c b/scripts/kconfig/preprocess.c
index 0243086..0590f86 100644 (file)
--- a/scripts/kconfig/preprocess.c
+++ b/scripts/kconfig/preprocess.c
@@ -114,7 +114,7 @@ static char *do_error_if(int argc, char *argv[])
        if (!strcmp(argv[0], "y"))
                pperror("%s", argv[1]);
 
-       return NULL;
+       return xstrdup("");
 }
 
 static char *do_filename(int argc, char *argv[])