RE: Unsigned widening casts of binary "not" operations..

[David Laight]

> > If the narrower type is signed it is probably even more confusing!
> > The high bits will be preserved unless you are masking off bit 31.
> 
> Yes. However, that case doesn't trigger with the normal case of small
> values. So "~4" works fine with widening, in a way that "~4u" does
> not.

Thinks ... converting:
	foo &= ~bar;
to:
	foo = ~(~foo | bar);
would generally DTRT.
Whether the compiler has the relevant patterns to optimise
it is another question.

	David

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