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3208. Boolean's expression requirements are ordered inconsistently

Section: 25.7 [iterator.range] Status: C++20 Submitter: Casey Carter Opened: 2019-06-06 Last modified: 2021-02-25

Priority: 0

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Discussion:

For consistency of presentation, we should group and order the && and || expression requirements similarly to the == and != expression requirements. Note that the suggested change is not quite editorial: evaluation of requirements for satisfaction has short-circuiting behavior, so the declaration order of requirements is normatively significant in general.

[2019-06-13; Priority to 0 and Status to Tentatively Ready after seven positive votes on the reflector.]

Proposed resolution:

This wording is relative to N4810.

1. Modify [concept.boolean] as indicated:

   […]
     { b1 } -> ConvertibleTo<bool>;
     { !b1 } -> ConvertibleTo<bool>;
     { b1 &&  a } -> Same<bool>;
     { b1 ||  a } -> Same<bool>;
     { b1 && b2 } -> Same<bool>;
     { b1 &&  a } -> Same<bool>;
     {  a && b2 } -> Same<bool>;
     { b1 || b2 } -> Same<bool>;
     { b1 ||  a } -> Same<bool>;
     {  a || b2 } -> Same<bool>;
     { b1 == b2 } -> ConvertibleTo<bool>;
     { b1 ==  a } -> ConvertibleTo<bool>;
     {  a == b2 } -> ConvertibleTo<bool>;
     { b1 != b2 } -> ConvertibleTo<bool>;
     { b1 !=  a } -> ConvertibleTo<bool>;
     {  a != b2 } -> ConvertibleTo<bool>;
   };