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poly_int marker value ¶It is sometimes useful to have a special “marker value” that is notmeant to be taken literally. For example, some code uses a sizeof -1 to represent an unknown size, rather than having to carry arounda separate boolean to say whether the size is known.
The best way of checking whether something is a marker value isknown_eq. Conversely the best way of checking whether somethingisnot a marker value ismaybe_ne.
Thus in the size example just mentioned, ‘known_eq (size, -1)’ wouldcheck for an unknown size and ‘maybe_ne (size, -1)’ would check for aknown size.