Hi, On 05/11/2015 09:02 AM, m-h-l wrote: > sorry, it was not my intention to complain about gcc and I never said it's a > defect. OK, I too am sorry for being rude. I thought your question rather aggressive, which it clearly was not intended to be. Mea culpa. I should not assume the worst. > I thought this is a help forum and so I thought I can get a hint or > trick how to work-around this. I really like gcc and you make a > great job with it. > > I just did not understand the idea behind this restriction. Perhaps > there is a good reason (beside the standard) for this. I don't think there is. There has to be some limit on how far to do constant propagation. This limit is necessarily arbitrary: there is no obvious point at which to say "this far, and no further." The need for a limit is especially true when the compiler is at -O0, with all optimizations turned off. There have to be rules about what expressions must be evaluated as constant expressions because we can use a constant expression as a key in a switch statement. Is it reasonable, then, to expect a simple C compiler always to look through all complex expressions at compile time? Where would you stop? The point I'm making is this: there is no one true answer. The standard makes a cut. Andrew.
