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[vector.bool.fmt][container.adaptors.format] Add missing constexpr #8768

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jensmaurer merged 1 commit into from
Mar 22, 2026
+5 −5
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[vector.bool.fmt][container.adaptors.format] Add missing constexpr #8768

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10 changes: 5 additions & 5 deletions source/containers.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -10735,7 +10735,7 @@
parse(ParseContext& ctx);

template<class FormatContext>
typename FormatContext::iterator
constexpr typename FormatContext::iterator
format(const T& ref, FormatContext& ctx) const;
};
}
Expand All @@ -10756,7 +10756,7 @@
\indexlibrarymember{format}{formatter}%
\begin{itemdecl}
template<class FormatContext>
typename FormatContext::iterator
constexpr typename FormatContext::iterator
format(const T& ref, FormatContext& ctx) const;
\end{itemdecl}

Expand Down Expand Up @@ -20308,7 +20308,7 @@
\tcode{queue},
\tcode{priority_queue}, and
\tcode{stack},
the library provides the following formatter specialization
the library provides the following constexpr-enabled formatter specialization
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@jensmaurer jensmaurer Mar 20, 2026

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"constexpr-enabled" does not imply "enabled" according to [format.formatter.spec], so this is a normative change.

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@jwakely jwakely Mar 20, 2026

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I think it's just a missing edit from the application of P3391, and similarly for the next change below.

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@jwakely jwakely Mar 20, 2026

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https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p3391r2.html#pnum_14

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@jwakely jwakely Mar 20, 2026

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So yes, it is a normative change, but one that was approved at plenary.

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@jensmaurer jensmaurer Mar 21, 2026 •
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So, you're saying this is a missed edit from the application of P3391R2, beyond a few sprinkled "constexpr" annotations ? That would be good to say in the commit comment.

But that causes an LWG issue, because "constexpr-enabled" doesn't imply "enabled", I think.

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@jwakely jwakely Mar 21, 2026 •
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We have:

If the library provides an explicit or partial specialization of formatter<T, charT>, that specialization is enabled and meets the Formatter requirements except as noted otherwise.

So I think these specializations are enabled just by virtue of being present in the library spec. We don't also need to say they're enabled

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@jensmaurer jensmaurer Mar 22, 2026

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Ok.

where \tcode{\placeholder{adaptor-type}} is the name of the template:

\indexlibraryglobal{formatter}%
Expand All @@ -20330,7 +20330,7 @@
parse(ParseContext& ctx);

template<class FormatContext>
typename FormatContext::iterator
constexpr typename FormatContext::iterator
format(@\exposid{maybe-const-adaptor}@& r, FormatContext& ctx) const;
};
}
Expand All @@ -20352,7 +20352,7 @@
\indexlibrarymember{format}{formatter}%
\begin{itemdecl}
template<class FormatContext>
typename FormatContext::iterator
constexpr typename FormatContext::iterator
format(@\exposid{maybe-const-adaptor}@& r, FormatContext& ctx) const;
\end{itemdecl}

Expand Down