Should the g_once_init_enter() argument be marked as volatile?

[dnn (Daniele Nicolodi)]

Hello,

the documentation https://developer.gnome.org/glib/stable/glib-Threads.html#g-once-init-enter says that g_once_init_enter() and g_once_init_leave() should not be marked volatile. And, indeed, I get an incompatible pointer type warning if I declare the parameter variable as such. However, if I don’t use volatileit seems that the function does not do what it is supposed to be doing.

I am working on Tracker and I wanted to get to a warning-free build, thus I tried to remove the volatile from the declarations of g_once_init_enter() sentinel variables . However, when I do this, a lot of tests fail.

Am I misinterpreting the documentation?

Thank you.

Cheers,
Dan

[dnn (Daniele Nicolodi)]

Ops. Please ignore. I found the problem and it does not have to do with volatile

[pwithnall (Philip Withnall)]

Glad you found the problem.

@dnn

Am I misinterpreting the documentation?

From what you’ve said, you are interpreting the documentation correctly (although I’d have to see a diff of what you’ve done to be sure). Previously, people (myself included) thought that volatile should be used to indicate a variable which is accessed atomically or by multiple threads, but that’s now understood to not be correct. volatile should basically never be used in C.