kconfig_lint: Check for IS_ENABLED used on symbols without CONFIG_

This looks at the coreboot codebase for the IS_ENABLED macro, and
gives an error if there is a symbol used without the CONFIG_ prefix.
This only works for symbols of type bool.

A future check will be added for all symbols, but that will take
a significant amount of time to run, because each symbol will need
to be searched for individually.

Change-Id: I92f2de2d231610d1a788da965f21966d89c2f25c
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/13538
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

util/lint/kconfig_lint

@@ -210,6 +210,27 @@ sub check_for_ifdef {
             }
         }
     }
+
+    my @collected_is_enabled;
+    if ($dont_use_git_grep) {
+        @collected_is_enabled =
+            `grep -Irn -- "[[:space:]]IS_ENABLED[[:space:]]*(.*)" | grep -v '$exclude_dirs_and_files' | grep -v "kconfig.h"`;
+    }
+    else {
+        @collected_is_enabled =
+            `git grep -In -- "[[:space:]]IS_ENABLED[[:space:]]*(.*)" | grep -v '$exclude_dirs_and_files' | grep -v "kconfig.h"`;
+    }
+
+    while ( my $line = shift @collected_is_enabled ) {
+        if ($line !~ /CONFIG_/ && $line =~ /^([^:]+):(\d+):.+IS_ENABLED\s*\(\s*(\w+)/ ) {
+            my $file   = $1;
+            my $lineno = $2;
+            my $symbol = $3;
+            if ( ( exists $symbols{$symbol} ) ) {
+                show_error("IS_ENABLED missing CONFIG_ prefix on symbol '$symbol' at $file:$lineno.");
+            }
+        }
+    }
 }
 
 #-------------------------------------------------------------------------------

util/lint/kconfig_lint_README

@@ -93,5 +93,6 @@ Errors in coreboot source files:
   defined in coreboot's version of Kconfig.
 - The IS_ENABLED macro is only valid for bool symbols.
 - The IS_ENABLED used on unknown CONFIG_ value, like an obsolete symbol.
+- The IS_ENABLED macro is used on a symbol without the CONFIG_ prefix.
 
 TODO: check for choice entries at the top level