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[2026-06 LWG Motion 3] P3798R1 The unexpected in std::expected #9127

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[2026-06 LWG Motion 3] P3798R1 The unexpected in std::expected #9127

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2 changes: 1 addition & 1 deletion source/support.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -674,7 +674,7 @@
#define @\defnlibxname{cpp_lib_exception_ptr_cast}@ 202603L // also in \libheader{exception}
#define @\defnlibxname{cpp_lib_exchange_function}@ 201304L // freestanding, also in \libheader{utility}
#define @\defnlibxname{cpp_lib_execution}@ 201902L // also in \libheader{execution}
#define @\defnlibxname{cpp_lib_expected}@ 202211L // also in \libheader{expected}
#define @\defnlibxname{cpp_lib_expected}@ 202606L // also in \libheader{expected}
#define @\defnlibxname{cpp_lib_filesystem}@ 201703L // also in \libheader{filesystem}
#define @\defnlibxname{cpp_lib_flat_map}@ 202511L // also in \libheader{flat_map}
#define @\defnlibxname{cpp_lib_flat_set}@ 202511L // also in \libheader{flat_set}
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30 changes: 30 additions & 0 deletions source/utilities.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -8524,6 +8524,7 @@
constexpr T&& operator*() && noexcept;
constexpr explicit operator bool() const noexcept;
constexpr bool has_value() const noexcept;
constexpr bool has_error() const noexcept;
constexpr const T& value() const &; // freestanding-deleted
constexpr T& value() &; // freestanding-deleted
constexpr const T&& value() const &&; // freestanding-deleted
Expand Down Expand Up @@ -9417,6 +9418,20 @@
\exposid{has_val}.
\end{itemdescr}

\indexlibrarymember{has_error}{expected}%
\begin{itemdecl}
constexpr bool has_error() const noexcept;
\end{itemdecl}

\begin{itemdescr}
\pnum
\effects
Equivalent to:
\begin{codeblock}
return !has_value();
\end{codeblock}
Comment on lines +9430 to +9432

@jwakely jwakely Jun 23, 2026

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I don't think this needs to be a codeblock, does it?

Suggested change
\begin{codeblock}
return !has_value();
\end{codeblock}
\tcode{return !has_value();}

(Also I wonder why we didn't ask for it to be just Returns: !has_value() since there are no preconditions or other special effects of has_value() that we need to inherit here.

\end{itemdescr}

\indexlibrarymember{value}{expected}%
\begin{itemdecl}
constexpr const T& value() const &;
Expand Down Expand Up @@ -9943,6 +9958,7 @@
// \ref{expected.void.obs}, observers
constexpr explicit operator bool() const noexcept;
constexpr bool has_value() const noexcept;
constexpr bool has_error() const noexcept;
constexpr void operator*() const noexcept;
constexpr void value() const &; // freestanding-deleted
constexpr void value() &&; // freestanding-deleted
Expand Down Expand Up @@ -10445,6 +10461,20 @@
\exposid{has_val}.
\end{itemdescr}

\indexlibrarymember{has_error}{expected<void>}%
\begin{itemdecl}
constexpr bool has_error() const noexcept;
\end{itemdecl}

\begin{itemdescr}
\pnum
\effects
Equivalent to:
\begin{codeblock}
return !has_value();
\end{codeblock}
Comment on lines +10473 to +10475

@jwakely jwakely Jun 23, 2026

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Suggested change
\begin{codeblock}
return !has_value();
\end{codeblock}
\tcode{return !has_value();}

\end{itemdescr}

\indexlibrarymember{operator*}{expected<void>}%
\begin{itemdecl}
constexpr void operator*() const noexcept;
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