kconfig_lint: restrict definition of defaults for choice elements

Defining defaults for symbols used inside choices is not allowed. Add a
check for this, so we can drop the existent, overly restrictive checks
in the follow-up change.

Change-Id: I45bce2633dbd168fceb81ceae9b68621b28526e8
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57715
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by:  Felix Singer <felixsinger@posteo.net>
Reviewed-by: Martin Roth <martinroth@google.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/util/lint/kconfig_lint b/util/lint/kconfig_lint
index 04c582a34eb6..7f26ef298f49 100755
--- a/util/lint/kconfig_lint
+++ b/util/lint/kconfig_lint
@@ -371,6 +371,12 @@ sub check_defaults {
                 # Make sure there's a type set for the symbol
                 next if (!defined $symbols{$sym}{type});
 
+                # Symbols created/used inside a choice must not have a default set. The default is set by the choice itself.
+                if ($symbols{$sym}{choice}) {
+                    show_error("Defining a default for symbol '$sym' at $filename:$line_no, used inside choice at "
+                               . "$symbols{$sym}{choice_loc}, is not allowed.");
+                }
+
                 # skip good defaults
                 if (! ((($symbols{$sym}{type} eq "hex") && ($symbols{$sym}{$sym_num}{default}{$def_num}{default} =~ /^0x/)) ||
                     (($symbols{$sym}{type} eq "int") && ($symbols{$sym}{$sym_num}{default}{$def_num}{default} =~ /^[-0-9]+$/)) ||
@@ -798,6 +804,9 @@ sub add_symbol {
         $symbols{$symbol}{count} = 0;
         if ($inside_choice) {
             $symbols{$symbol}{choice} = 1;
+
+            # remember the location of the choice
+            $symbols{$symbol}{choice_loc} = join(':', (split / /, $inside_choice));
         }
         else {
             $symbols{$symbol}{choice} = 0;