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P2614R2 Deprecate numeric_limits::has_denorm #6141

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Mar 12, 2023
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P2614R2 Deprecate numeric_limits::has_denorm #6141

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42 changes: 42 additions & 0 deletions source/future.tex
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Expand Up @@ -218,6 +218,48 @@
unless the function's \throws element
specifies throwing an exception when the precondition is violated.

\rSec1[depr.numeric.limits.has.denorm]{\tcode{has_denorm} members in \tcode{numeric_limits}}

\pnum
The following type is defined
in addition to those specified in \libheaderref{limits}:
\indexlibraryglobal{float_denorm_style}%
\begin{codeblock}
namespace std {
enum float_denorm_style {
denorm_indeterminate = -1,
denorm_absent = 0,
denorm_present = 1
};
}
\end{codeblock}

\pnum
\indextext{denormalized value|see{number, subnormal}}%
\indextext{value!denormalized|see{number, subnormal}}%
\indextext{subnormal number|see{number, subnormal}}%
\indextext{number!subnormal}%
The following members are defined
in addition to those specified in \ref{numeric.limits.general}:
\begin{codeblock}
static constexpr float_denorm_style has_denorm = denorm_absent;
static constexpr bool has_denorm_loss = false;
\end{codeblock}

\pnum
The values of \tcode{has_denorm} and \tcode{has_denorm_loss} of
specializations of \tcode{numeric_limits} are unspecified.

\pnum
The following members of the specialization \tcode{numeric_limits<bool>} are defined
in addition to those specified in \ref{numeric.special}:
\indexlibrarymember{float_denorm_style}{numeric_limits}%
\indexlibrarymember{has_denorm_loss}{numeric_limits}%
\begin{codeblock}
static constexpr float_denorm_style has_denorm = denorm_absent;
static constexpr bool has_denorm_loss = false;
\end{codeblock}

\rSec1[depr.c.macros]{Deprecated C macros}

\pnum
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97 changes: 4 additions & 93 deletions source/support.tex
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Expand Up @@ -759,14 +759,12 @@
\indextext{\idxcode{numeric_limits}}%
\indexlibraryglobal{numeric_limits}%
\indexlibraryglobal{float_round_style}%
\indexlibraryglobal{float_denorm_style}%

\begin{codeblock}
// all freestanding
namespace std {
// \ref{fp.style}, floating-point type properties
// \ref{round.style}, enumeration \tcode{float_round_style}
enum float_round_style;
enum float_denorm_style;

// \ref{numeric.limits}, class template \tcode{numeric_limits}
template<class T> class numeric_limits;
Expand Down Expand Up @@ -800,9 +798,7 @@
}
\end{codeblock}

\rSec2[fp.style]{Floating-point type properties}

\rSec3[round.style]{Type \tcode{float_round_style}}
\rSec2[round.style]{Enum \tcode{float_round_style}}

\indexlibraryglobal{float_round_style}%
\begin{codeblock}
Expand Down Expand Up @@ -843,41 +839,6 @@
if the rounding style is toward negative infinity
\end{itemize}

\rSec3[denorm.style]{Type \tcode{float_denorm_style}}

\indexlibraryglobal{float_denorm_style}%
\begin{codeblock}
namespace std {
enum float_denorm_style {
denorm_indeterminate = -1,
denorm_absent = 0,
denorm_present = 1
};
}
\end{codeblock}

\indextext{denormalized value|see{number, subnormal}}%
\indextext{value!denormalized|see{number, subnormal}}%
\indextext{subnormal number|see{number, subnormal}}%
\indextext{number!subnormal}%
\pnum
The presence or absence of subnormal numbers (variable number of exponent bits)
is characterized by the values:
\begin{itemize}
\item
\indexlibraryglobal{denorm_indeterminate}%
\tcode{denorm_indeterminate}
if it cannot be determined whether or not the type allows subnormal values
\item
\indexlibraryglobal{denorm_absent}%
\tcode{denorm_absent}
if the type does not allow subnormal values
\item
\indexlibraryglobal{denorm_present}%
\tcode{denorm_present}
if the type does allow subnormal values
\end{itemize}

\rSec2[numeric.limits]{Class template \tcode{numeric_limits}}

\rSec3[numeric.limits.general]{General}
Expand Down Expand Up @@ -918,8 +879,6 @@
static constexpr bool has_infinity = false;
static constexpr bool has_quiet_NaN = false;
static constexpr bool has_signaling_NaN = false;
static constexpr float_denorm_style has_denorm = denorm_absent;
static constexpr bool has_denorm_loss = false;
static constexpr T infinity() noexcept { return T(); }
static constexpr T quiet_NaN() noexcept { return T(); }
static constexpr T signaling_NaN() noexcept { return T(); }
Expand Down Expand Up @@ -1340,46 +1299,6 @@
\tcode{is_iec559 != false}.
\end{itemdescr}

\indexlibrarymember{float_denorm_style}{numeric_limits}%
\begin{itemdecl}
static constexpr float_denorm_style has_denorm;
\end{itemdecl}

\indextext{number!subnormal}%
\begin{itemdescr}
\pnum
\tcode{denorm_present}
if the type allows subnormal values
(variable number of exponent bits),
\begin{footnote}
Required by LIA-1.
\end{footnote}
\tcode{denorm_absent}
if the type does not allow subnormal values,
and
\tcode{denorm_indeterminate}
if it is indeterminate at compile time whether the type allows
subnormal values.

\pnum
Meaningful for all floating-point types.
\end{itemdescr}

\indexlibrarymember{has_denorm_loss}{numeric_limits}%
\begin{itemdecl}
static constexpr bool has_denorm_loss;
\end{itemdecl}

\begin{itemdescr}
\pnum
\tcode{true} if loss of accuracy is detected as a
denormalization loss, rather than as an inexact result.
\begin{footnote}
See
ISO/IEC/IEEE 60559.
\end{footnote}
\end{itemdescr}

\indexlibrarymember{infinity}{numeric_limits}%
\begin{itemdecl}
static constexpr T infinity() noexcept;
Expand Down Expand Up @@ -1445,18 +1364,14 @@
\begin{itemdescr}
\indextext{number!subnormal}%
\pnum
Minimum positive subnormal value.
Minimum positive subnormal value, if available.
\begin{footnote}
Required by LIA-1.
\end{footnote}
Otherwise, minimum positive normalized value.

\pnum
Meaningful for all floating-point types.

\pnum
In specializations for which
\tcode{has_denorm == false},
returns the minimum positive normalized value.
\end{itemdescr}

\indexlibrarymember{is_iec559}{numeric_limits}%
Expand Down Expand Up @@ -1630,8 +1545,6 @@
static constexpr bool has_infinity = true;
static constexpr bool has_quiet_NaN = true;
static constexpr bool has_signaling_NaN = true;
static constexpr float_denorm_style has_denorm = denorm_absent;
static constexpr bool has_denorm_loss = false;

static constexpr float infinity() noexcept { return @\textit{value}@; }
static constexpr float quiet_NaN() noexcept { return @\textit{value}@; }
Expand Down Expand Up @@ -1683,8 +1596,6 @@
static constexpr bool has_infinity = false;
static constexpr bool has_quiet_NaN = false;
static constexpr bool has_signaling_NaN = false;
static constexpr float_denorm_style has_denorm = denorm_absent;
static constexpr bool has_denorm_loss = false;
static constexpr bool infinity() noexcept { return 0; }
static constexpr bool quiet_NaN() noexcept { return 0; }
static constexpr bool signaling_NaN() noexcept { return 0; }
Expand Down
4 changes: 4 additions & 0 deletions source/xrefdelta.tex
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Expand Up @@ -110,5 +110,9 @@
\movedxref{expos.only.func}{expos.only.entity}
\removedxref{expos.only.types}

% P2614R2 Deprecate numeric_limits::has_denorm
\movedxref{denorm.style}{depr.numeric.limits.has.denorm}
\removedxref{fp.style}

% Deprecated features.
%\deprxref{old.label} (if moved to depr.old.label, otherwise use \movedxref)