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[iterator.concept.winc] Refactor definition of "integer-like type" #8763

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[iterator.concept.winc] Refactor definition of "integer-like type" #8763

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15 changes: 6 additions & 9 deletions source/iterators.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -1445,15 +1445,12 @@
that of every integral type of the same signedness.

\pnum
A type \tcode{I} other than \cv{}~\tcode{bool} is \defn{integer-like}
if it models \tcode{\libconcept{integral}<I>} or
if it is an integer-class type.
An integer-like type \tcode{I} is \defn{signed-integer-like}
if it models \tcode{\libconcept{signed_integral}<I>} or
if it is a signed-integer-class type.
An integer-like type \tcode{I} is \defn{unsigned-integer-like}
if it models \tcode{\libconcept{unsigned_integral}<I>} or
if it is an unsigned-integer-class type.
Integer-class types and integral types\iref{basic.fundamental} other than \cv{}~\tcode{bool}
are collectively called \defnadjx{integer-like}{types}{type}.
Signed-integer-class types and types that model \tcode{\libconcept{signed_integral}}
are collectively called \defnadjx{signed-integer-like}{types}{type}.
Unsigned-integer-class types, and types other than \cv{}~\tcode{bool} that model \tcode{\libconcept{unsigned_integral}},
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@jensmaurer jensmaurer Feb 26, 2026

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Where is this "bool" exclusion coming from? It's not in the original text for unsigned-integer-like.

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@Quuxplusone Quuxplusone Feb 26, 2026

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The original text is

An integer-like type I is unsigned-integer-like if it models unsigned_integral<I> or if it is an unsigned-integer-class type.

Now, is bool an unsigned-integer-like type? Arguably the reader can't use the original sentence to say one way or the other, since the original sentence tells us anything at all only for "an integer-like type," which bool isn't.

But the intent, I think, is that the unsigned-integer-like types should be a strict subset of the integer-like types.

Suppose the new text was:

Unsigned-integer-class types, and types other than cv bool that model unsigned_integral, are collectively called unsigned-integer-like types.

Then bool (which models unsigned_integral) would be considered unsigned-integer-like but not integer-like. I'm sure we don't intend that.

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@Quuxplusone Quuxplusone Feb 26, 2026

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Alternatively, how about this? (Signed-integer-class types and unsigned-integer-class types are collectively known as integer-class types: [iterator.concept.winc]/3.)

Signed-integer-class types and types that model \tcode{\libconcept{signed_integral}}
are collectively called \defnadjx{signed-integer-like}{types}{type}.
Unsigned-integer-class types, and types other than \cv{}~\tcode{bool} that model \tcode{\libconcept{unsigned_integral}},
are collectively called \defnadjx{unsigned-integer-like}{types}{type}.
Signed-integer-like types and unsigned-integer-like types
are collectively called \defnadjx{integer-like}{types}{type}.

This puts the "except bool" exception in just one place instead of two, and makes it very clear that integer-like types are precisely partitioned into signed and unsigned just like integer-class types are partitioned into signed and unsigned and integral types are partitioned into signed and unsigned.

are collectively called \defnadjx{unsigned-integer-like}{types}{type}.

\pnum
For every integer-class type \tcode{I},
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