[PATCH] power: supply: move power_supply_attr_group into #ifdef block

[Ricardo B. Marliere]

When building with CONFIG_SYSFS=n, the build error below is triggered:

ld: drivers/power/supply/power_supply_core.o:(.data+0x0): undefined
reference to `power_supply_attr_group'

The problem is that power_supply_attr_group is needed in
power_supply_core.c but defined in power_supply_sysfs.c, which is only
targeted with CONFIG_SYSFS=y. Therefore, move the extern declaration into
the #ifdef block that checks for CONFIG_SYSFS, and define an empty static
const struct otherwise. This is safe because the macro __ATRIBUTE_GROUPS in
power_supply_core.c will expand into an empty attribute_group array.

Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Link: https://lore.kernel.org/all/20240227214916.GA3699076@dev-arch.thelio-3990X/
Fixes: 7b46b60944d7 ("power: supply: core: constify the struct device_type usage")
Signed-off-by: Ricardo B. Marliere <ricardo@xxxxxxxxxxxx>
---
This patch depends on [1].
[1]: 20240227-fix-power_supply_init_attrs-stub-v1-1-43365e68d4b3@xxxxxxxxxx
---
 drivers/power/supply/power_supply.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/power/supply/power_supply.h b/drivers/power/supply/power_supply.h
index 7d05756398b9..06749a534db4 100644
--- a/drivers/power/supply/power_supply.h
+++ b/drivers/power/supply/power_supply.h
@@ -13,16 +13,16 @@ struct device;
 struct device_type;
 struct power_supply;
 
-extern const struct attribute_group power_supply_attr_group;
-
 #ifdef CONFIG_SYSFS
 
 extern void power_supply_init_attrs(void);
 extern int power_supply_uevent(const struct device *dev, struct kobj_uevent_env *env);
+extern const struct attribute_group power_supply_attr_group;
 
 #else
 
 static inline void power_supply_init_attrs(void) {}
+static const struct attribute_group power_supply_attr_group;
 #define power_supply_uevent NULL
 
 #endif /* CONFIG_SYSFS */

---
base-commit: 837af6b0cdb2b8df56d2df35db0444cfa1ea47c2
change-id: 20240228-device_cleanup-power-2dcfaa7b7f2b

Best regards,
-- 
Ricardo B. Marliere <ricardo@xxxxxxxxxxxx>