I'm working on a no_std application, WITHOUT atomics, becuase my processor doesn't support the necessary instructions for that. (thumbv6-m, cortex-m0, no strex, ldrex instructions). It can be emulated by disabling interrupts, but that doesn't magically make
core::atomics to be compiled in.
lazy_static! unavailable because it relies on
So basically I can't have static variables that are not const, but some of my statics (such as creating a freertos mutex, which calls into C code using FFI) cannot be made const, and I highly doubt FFI will ever be const, especially since it includes heap allocation for the FreeRTOS mutex object
I also propose the ability to create static variables that are initialized when starting up the application. In embedded space, this is requires additional discussion, since we need to pick an place when the statics' initialization will take place. The user needs to be able to inject code before that happens to initialize the RAM controller for example, and to set up the stack. Perhaps a special function could be generated that deals with this, and the user would be responsible to call that at the correct time.
I haven't done the math, but I would suspect the compiler could perhaps create a dependency graph of which non-const static refers to which another one, and initialize them in the correct order.
This would make lazy_static mostly obsolete, because in many cases lazy_static is not used for lazy initialization, but rather to circumvent this limitation of static variables, thus it's used to initialize "stuff" before first use, and the requirement is only that, and it is not necessary for it to happen as late as possible.
Before investing more effort on this, I'd like to hear your thoughts, and perhaps I can make an RFC out of this if there seems to be a general opinion that it's worth exploring.