Suggest using volatile attribute on ptYielded

[Xeenych]

If protothread does not have any PT_YIELD() in its Run method then compiler produces a warning, that ptYielded is set but never used.

I suggest using volatile attribute on ptYilded so compiler won't optimize (void) ptYielded; statement and won't produce any warnings.

#define PT_BEGIN() bool volatile ptYielded = true; (void) ptYielded; switch (_ptLine) { case 0:

For example I have this code without any PT_YILED()

		PT_BEGIN();
		PT_SPAWN(task1);
		PT_SPAWN(task2);
		
		readtask.Run();
		task3.Run();
		PT_WAIT_THREAD(readtask);
		PT_WAIT_THREAD(task3);
		//PT_YIELD();
		PT_END();

[benhoyt]

Sorry for not responding to this earlier! I'm curious (and I haven't written a lot of C for a while): why doesn't the (void) ptYielded cause the compiler to not produce a warning here?

[marek22k]

Alternatively, you could use __attribute__((unused)).

[marek22k]

why doesn't the (void) ptYielded cause the compiler to not produce a warning here?

This will cast it to the type void. The compiler then seems to think that the value is used because it was casted.

[cmorty]

volatile is a very bad idea and was deprecated in current C++ - standards, except for hardware-registers, for good reasons (mainly because a lot of people did not understand the implications on multi-core systems).
@Xeenych : I wonder which compiler ignores the void-cast and gives you a warning about unused ptYielded.
@marek22k : __attribute__((unused)) is a gcc extension (and [maybe_unused] is C++23 ;-) )