gcc: why is "abcdef" not a constant (error: initializer element is not constant)
Mon May 11 09:40:00 GMT 2015
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
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.
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