unused function warning message（转）

This object function is static,
static function if no other access to the function, then
at the compile time, unused error will occur,
can be added before the function  attribute ((unused)) to avoid unused error,
but if the real function of the body when there is for error, will be detected.

Case 1

function not being accessed

1335 static irqreturn_t xxx_handler(int irq, void *data)                                                                       
 1336 {
 1337         struct smbchg_chip *chip = (struct smbchg_chip *)data;
  .....
  .....

.....
.....
android/kernel/msm-3.18/drivers/power/qpnp-smbcharger.c:1335:20: warning: 'xxx_handler' defined but not used [-Wunused-function]
error, forbidden warning: qpnp-smbcharger.c:1335
make[3]: *** [drivers/power/qpnp-smbcharger.o] Error 1
make[2]: *** [drivers/power] Error 2
make[1]: *** [drivers] Error 2
make[1]: *** Waiting for unfinished jobs....
.....
.....
.....

Case 2

function has not been accessed and adding  attribute ((unused))

1335 __attribute__((unused)) static irqreturn_t xxx_handler(int irq, void *data)                                                                       
 1336 {
 1337         struct smbchg_chip *chip = (struct smbchg_chip *)data;
  .....
  .....
  .....

compile success

Case 3

function has not been accessed and adding  attribute ((unused)) and the error function has a body

1335 static _attribute__((unused)) irqreturn_t xxx_handler(int irq, void *data)
 1336 {
 1337         asfadsf
 1338         struct smbchg_chip *chip = (struct smbchg_chip *)data;  .....
  .....
  .....

.....
.....
android/kernel/msm-3.18/drivers/power/qpnp-smbcharger.c:1337:9: error: 'asfadsf' undeclared (first use in this function)
         asfadsf
         ^
.....
.....

The timing of the application

When the coder is still under implementation function of the body, and want to check whether there is an error, you can use

 

Transfer: https://www.cnblogs.com/youchihwang/p/8986370.html