if its controlling expression is not a constant expression
Pretty big caveat. If I’m reading this right true definitely qualifies as a constant expression and the loop in the meme would therefore not be optimized away.
Accesses to volatile objects and calls to library I/O functions are observable behavior. The implementation may perform any transformation of a program, provided that the resulting program’s observable behavior is not changed.
So it seems that running forever isn’t an observable property that must be preserved when code is transformed.
Still, I think compilers try to not surprise the developer too badly and would recognize a trivial loop most of the time.
Pretty big caveat. If I’m reading this right
truedefinitely qualifies as a constant expression and the loop in the meme would therefore not be optimized away.There’s also this part of the standard that throws a wrench into this hypothesis:
§5.1.2.3/4: (Program execution, Observable behavior):
So it seems that running forever isn’t an observable property that must be preserved when code is transformed.
Still, I think compilers try to not surprise the developer too badly and would recognize a trivial loop most of the time.