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[2026-06 LWG Motion 8] P3154R3 (Deprecating signed character types in iostreams) #9122

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[2026-06 LWG Motion 8] P3154R3 (Deprecating signed character types in iostreams) #9122

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a2b2fd2
P3154R3 Deprecating signed character types in iostreams
notdanhan Jun 14, 2026
894eac8
fixup: deal with overflowing hbox
notdanhan Jun 15, 2026
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95 changes: 95 additions & 0 deletions source/future.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -1051,3 +1051,98 @@
\returns
\tcode{y}.
\end{itemdescr}

\Sec1[depr.istream.extractors]{Deprecated \tcode{signed char} and \tcode{unsigned char} extraction}
\pnum
The header \libheaderref{istream} has the following additions:

\begin{itemdecl}
template<class traits>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, unsigned char& c);
template<class traits>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, signed char& c);
\end{itemdecl}

\begin{itemdescr}
\pnum
\effects
Behaves like a formatted input member (as described in\iref{istream.formatted.reqmts}) of \tcode{in}.
A character is extracted from \tcode{in}, if one is available, and stored in \tcode{c}. Otherwise,
\tcode{ios_base::failbit} is set in the input function's local error state before setstate is called.
\pnum
\returns
\tcode{in}
\end{itemdescr}

\pnum
\begin{itemdecl}
template<class traits, size_t N>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, unsigned char (&s)[N]);
template<class traits, size_t N>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, signed char (&s)[N]);
\end{itemdecl}

\begin{itemdescr}
\pnum
\effects
Behaves like a formatted input member (as described in\iref{istream.formatted.reqmts}) of \tcode{in}.
After a sentry object is constructed, \tcode{operator>>} extracts characters and stores them into \tcode{s}.
If \tcode{width()} is greater than zero, \tcode{n} is \tcode{min(size_t(width()), N)}.
Otherwise \tcode{n} is \tcode{N}. \tcode{n} is the maximum number of characters stored.

\pnum
Characters are extracted and stored until any of the following occurs:
\begin{itemize}
\item \tcode{n - 1} characters are stored;
\item end of file occurs on the input sequence;
\item letting \tcode{ct} be \tcode{use_facet<ctype<charT>>(in.getloc())}, \tcode{ct.is(ct.space, s)}
is \tcode{true}.
\end{itemize}

\pnum
\tcode{operator>>} then stores a null byte (\tcode{charT()}) in the next position,
which may be the first position if no characters were extracted.
\tcode{operator>>} then calls \tcode{width(0)}.

\pnum
If the function extracted no characters, \tcode{ios_bit::failbit} is set in the input function's local
error state before \tcode{setstate} is called.

\pnum
\returns
\tcode{in}.
\end{itemdescr}

\Sec1[depr.ostream.inserters]{Deprecated \tcode{signed char} and \tcode{unsigned char} insertion}
\pnum
The header \libheaderref{ostream} has the following additions:

\pnum
\begin{itemdecl}
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out, signed char c);
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out, unsigned char c);
\end{itemdecl}

\begin{itemdescr}
\pnum
\effects
Equivalent to: \tcode{return out << static_cast<char>(c);}
\end{itemdescr}

\pnum
\begin{itemdecl}
template<class traits>
basic_ostream<char, traits>&
operator<<(basic_ostream<char, traits>& out, const signed char* s);
template<class traits>
basic_ostream<char, traits>&
operator<<(basic_ostream<char, traits>& out, const unsigned char* s);
\end{itemdecl}

\begin{itemdescr}
\pnum
\effects
Equivalent to: \tcode{return out << reinterpret_cast<const char*>(s);}
\end{itemdescr}
39 changes: 0 additions & 39 deletions source/iostreams.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -4387,17 +4387,9 @@
// \ref{istream.extractors}, character extraction templates
template<class charT, class traits>
basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>&, charT&);
template<class traits>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, unsigned char&);
template<class traits>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, signed char&);

template<class charT, class traits, size_t N>
basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>&, charT(&)[N]);
template<class traits, size_t N>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, unsigned char(&)[N]);
template<class traits, size_t N>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>&, signed char(&)[N]);
}
\end{codeblock}

Expand Down Expand Up @@ -4919,10 +4911,6 @@
\begin{itemdecl}
template<class charT, class traits, size_t N>
basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>& in, charT (&s)[N]);
template<class traits, size_t N>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, unsigned char (&s)[N]);
template<class traits, size_t N>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, signed char (&s)[N]);
\end{itemdecl}

\begin{itemdescr}
Expand Down Expand Up @@ -4976,10 +4964,6 @@
\begin{itemdecl}
template<class charT, class traits>
basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>& in, charT& c);
template<class traits>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, unsigned char& c);
template<class traits>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, signed char& c);
\end{itemdecl}

\begin{itemdescr}
Expand Down Expand Up @@ -6003,11 +5987,6 @@
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, char);

template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, signed char);
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, unsigned char);

template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, wchar_t) = delete;
template<class traits>
Expand All @@ -6033,11 +6012,6 @@
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const char*);

template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const signed char*);
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const unsigned char*);

template<class traits>
basic_ostream<char, traits>&
operator<<(basic_ostream<char, traits>&, const wchar_t*) = delete;
Expand Down Expand Up @@ -6719,11 +6693,6 @@
// specialization
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out, char c);
// signed and unsigned
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out, signed char c);
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out, unsigned char c);
\end{itemdecl}

\begin{itemdescr}
Expand Down Expand Up @@ -6755,11 +6724,6 @@
basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& out, const char* s);
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out, const char* s);
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out, const signed char* s);
template<class traits>
basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>& out,
const unsigned char* s);
\end{itemdecl}

\begin{itemdescr}
Expand Down Expand Up @@ -6791,9 +6755,6 @@
\tcode{basic_ostream<charT, traits>\&}
and the second is of type
\tcode{const char*},
\item
\tcode{traits::length(reinterpret_cast<const char*>(s))}
for the other two overloads.
\end{itemize}
Determines padding for \tcode{seq} as described
in~\ref{ostream.formatted.reqmts}. Inserts \tcode{seq} into
Expand Down
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