On Tue, May 26, 2026 at 5:09 PM Tomasz Kamiński <[email protected]> wrote:
> This implements the interface changes from > LWG1439, "Return from densities() functions?". > > Due the ABI concerns, we cannot change the the element_type of member > (_M_den, _M_cp, and _M_m) vectors, and we convert the _M_den values > to result_type when function is invoked. However, as the usage of > distributions with types other than float, double, and long double > is either undefined (pre C++26) or implementaiton-defined (post C++26), > this limitation de-fact applies to float, and long double (if it's > different size than double). > > To handle above we introduce the __piecewise_distributions_storage<_Tp> > alias, whose type nested typedef points to double in above two cases, > and _Tp otherwise. This alias is used to define _StorageType nested > type, that is then used in defintion of _M_den, _M_cp, and _M_m members. > In consequence for extended floating point types (__float128, std::float16, > ...) for which ABI can be changed, we store densitiees (and other values) > as result_type. > > For user that can accept above ABI change, we introduce a macro > _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES, that result in > _StorageType being unconditionally defined as _RealType (result_type), > and thus adjust internal storage also for float and long double. > > To avoid symbol conflicts, the param_type::densities member functions > are marked with "__rt" ABI tag. The corresponding members of the > distributions are modified to invoke param_type method, and marked > as always_inline. For consistency intervals methods are adjusted same > way. > > Finally, to preserve current behavior, the operators>> load densities > as values of _StorageType. > > libstdc++-v3/ChangeLog: > > * doc/xml/manual/using.xml > (_GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES): Add entry. > * doc/html/manual/using_macros.html: Regenerate. > * include/bits/random.h > (__detail::__piecewise_distributions_storage) > (piecewise_constant_distribution::_StorageType) > (piecewise_linear_distribution::_StorageType): Define. > (piecewise_constant_distribution::param_type::_M_den) > (piecewise_constant_distribution::param_type::_M_cp) > (piecewise_linear_distribution::param_type::_M_den) > (piecewise_linear_distribution::param_type::_M_cp) > (piecewise_linear_distribution::param_type::_M_m): Use _StorageType > as element type. > (piecewise_constant_distribution::param_type::densities) > (piecewise_linear_distribution::param_type::densities): Change > return type to vector<result_type>, mark with "__rt" ABI tag, > and adjust implementation. > (piecewise_constant_distribution::param_type::intervals) > (piecewise_linear_distribution::param_type::intervals): Use > result_type alias in return type. > (piecewise_constant_distribution::densities) > (piecewise_linear_distribution::densities): Delegate to param_type > method, and mark as always_inline. > (piecewise_constant_distribution::intervals) > (piecewise_linear_distribution::intervals): Delegate to param_type > method and use result_type alias in return type. > * include/bits/random.tcc > (operator<<(basic_ostream&, const > piecewise_constant_distribution&)) > (operator<<(basic_ostream&, const piecewise_linear_distribution&)): > Parse vector of _StorageType for densities, to preserve behavior. > * > testsuite/26_numerics/random/piecewise_constant_distribution/operators/accessors.cc: > New test. > * > testsuite/26_numerics/random/piecewise_linear_distribution/operators/accessors.cc: > New test. > * > testsuite/26_numerics/random/piecewise_constant_distribution/operators/accessors_exact.cc: > Run accessors.cc with > _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES. > * > testsuite/26_numerics/random/piecewise_linear_distribution/operators/accessors_exact.cc: > Likewise. > --- > The commit description is pretty long, but the change are > are not really. Handling extra define to force usage of > correct result type was trivial, so I have added it. > > Testing on x86_64-linux. All *piecewise* test passed, > including serializaiton one. > OK for trunk when all test passes? > > .../doc/html/manual/using_macros.html | 11 ++ > libstdc++-v3/doc/xml/manual/using.xml | 17 +++ > libstdc++-v3/include/bits/random.h | 141 ++++++++++++------ > libstdc++-v3/include/bits/random.tcc | 10 +- > .../operators/accessors.cc | 73 +++++++++ > .../operators/accessors_exact.cc | 5 + > .../operators/accessors.cc | 75 ++++++++++ > .../operators/accessors_exact.cc | 5 + > 8 files changed, 292 insertions(+), 45 deletions(-) > create mode 100644 > libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/operators/accessors.cc > create mode 100644 > libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/operators/accessors_exact.cc > create mode 100644 > libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/operators/accessors.cc > create mode 100644 > libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/operators/accessors_exact.cc > > diff --git a/libstdc++-v3/doc/html/manual/using_macros.html > b/libstdc++-v3/doc/html/manual/using_macros.html > index f1d8492fb9e..ea32f065bea 100644 > --- a/libstdc++-v3/doc/html/manual/using_macros.html > +++ b/libstdc++-v3/doc/html/manual/using_macros.html > @@ -156,4 +156,15 @@ > <code class="option">-fexec-charset=UTF-8</code> so might give > incorrect results > if called from a source file that uses a non-Unicode encoding, > especially for format strings using non-ASCII fill characters. > + </p></dd><dt><span class="term"><code > class="code">_GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES</code></span></dt><dd><p> > + Undefined by default. When defined specializations of > + <code class="code">piecewise_constant_distribution</code> and > + <code class="code">piecewise_linear_distribution</code> for <code > class="code">float</code> or > + <code class="code">long double</code> <code > class="code">result_type</code>, stores value of > + densities (and other state) as <code > class="code">result_type</code> (instead of > + <code class="code">double</code>). This complete the resolution of > library issue > + <a class="link" href="https://cplusplus.github.io/LWG/issue1439"; > target="_top"> > + 1449. Return from densities() functions?</a>, however makes their > + representation ABI incompatible with one used by translation units > + compiled without this flag, including older GCC releases. > </p></dd></dl></div></div><div class="navfooter"><hr /><table > width="100%" summary="Navigation footer"><tr><td width="40%" > align="left"><a accesskey="p" href="using_headers.html">Prev</a> </td><td > width="20%" align="center"><a accesskey="u" > href="using.html">Up</a></td><td width="40%" align="right"> <a > accesskey="n" href="using_dual_abi.html">Next</a></td></tr><tr><td > width="40%" align="left" valign="top">Headers </td><td width="20%" > align="center"><a accesskey="h" href="../index.html">Home</a></td><td > width="40%" align="right" valign="top"> Dual > ABI</td></tr></table></div></body></html> > \ No newline at end of file > diff --git a/libstdc++-v3/doc/xml/manual/using.xml > b/libstdc++-v3/doc/xml/manual/using.xml > index e2e75e8fe28..d71dd13703b 100644 > --- a/libstdc++-v3/doc/xml/manual/using.xml > +++ b/libstdc++-v3/doc/xml/manual/using.xml > @@ -1379,6 +1379,23 @@ g++ -Winvalid-pch -I. -include stdc++.h -H -g -O2 > hello.cc -o test.exe > especially for format strings using non-ASCII fill characters. > </para> > </listitem></varlistentry> > + > <varlistentry><term><code>_GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES</code></term> > + <listitem> > + <para> > + Undefined by default. When defined specializations of > + <code>piecewise_constant_distribution</code> and > + <code>piecewise_linear_distribution</code> for <code>float</code> > or > + <code>long double</code> <code>result_type</code>, stores value of > + densities (and other state) as <code>result_type</code> (instead of > + <code>double</code>). This complete the resolution of library issue > + <link xmlns:xlink="http://www.w3.org/1999/xlink"; > + xlink:href="https://cplusplus.github.io/LWG/issue1439";> > + 1449. Return from densities() functions?</link>, however makes > their > + representation ABI incompatible with one used by translation units > + compiled without this flag, including older GCC releases. > + </para> > + </listitem></varlistentry> > + > </variablelist> > > </section> > diff --git a/libstdc++-v3/include/bits/random.h > b/libstdc++-v3/include/bits/random.h > index a0592a00763..05cdb44ff95 100644 > --- a/libstdc++-v3/include/bits/random.h > +++ b/libstdc++-v3/include/bits/random.h > @@ -6385,6 +6385,33 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > { return !(__d1 == __d2); } > #endif > > +#ifndef _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES > + namespace __detail > + { > + template<typename _Tp> > + struct __piecewise_distributions_storage > + { using type = _Tp; }; > + > + template<> > + struct __piecewise_distributions_storage<float> > + { using type = double; }; > + > +# ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT > + template<> > + struct __piecewise_distributions_storage<__ibm128> > + { using type = double; }; > + > + template<> > + struct __piecewise_distributions_storage<__ieee128> > + { using type = double; }; > +# elif __LDBL_MANT_DIG__ != __DBL_MANT_DIG__ > + template<> > + struct __piecewise_distributions_storage<long double> > + { using type = double; }; > +# endif > + } > +#endif // _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES > + > /** > * @brief A piecewise_constant_distribution random number distribution. > * > @@ -6406,6 +6433,12 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > { > static_assert(std::is_floating_point<_RealType>::value, > "result_type must be a floating point type"); > + using _StorageType > +#ifdef _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES > + = _RealType; > +#else > + = typename > __detail::__piecewise_distributions_storage<_RealType>::type; > +#endif > I think it would be better to introduce __detail::__piecewise_distributions_storage_t alias defined as follows, and keep the logic in one place: namespace __detail { +#ifdef _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES + template<typename _Tp> + using __piecewise_distributions_storage_t = _Tp; +#else template<typename _Tp> struct __piecewise_distributions_storage { using type = _Tp; }; @@ -6409,8 +6412,12 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) struct __piecewise_distributions_storage<long double> { using type = double; }; # endif - } + + template<typename _Tp> + using __piecewise_distributions_storage_t + = typename __piecewise_distributions_storage<_Tp>::type; #endif // _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES + } Done the change above locally: > public: > /** The type of the range of the distribution. */ > @@ -6437,7 +6470,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > param_type(const param_type&) = default; > param_type& operator=(const param_type&) = default; > > - std::vector<_RealType> > + std::vector<result_type> > intervals() const > { > if (_M_int.empty()) > @@ -6450,9 +6483,28 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > return _M_int; > } > > - std::vector<double> > + // _GLIBCXX_RESOLVE_LIB_DEFECTS > + // 1439. Return from densities() functions? > + [[__gnu__::__abi_tag__("__rt")]] > + std::vector<result_type> > densities() const > - { return _M_den.empty() ? std::vector<double>(1, 1.0) : _M_den; } > + { > +#pragma GCC diagnostic push > +#pragma GCC diagnostic ignored "-Wc++17-extensions" > + if (_M_den.empty()) > + return std::vector<_RealType>(1, _RealType(1)); > + else if constexpr (is_same<_RealType, _StorageType>::value) > + return _M_den; > + else > + { > + std::vector<_RealType> __res; > + __res.reserve(_M_den.size()); > + for (_RealType __v : _M_den) > + __res.push_back(__v); > + return __res; > + } > +#pragma GCC diagnostic pop > + } > > friend bool > operator==(const param_type& __p1, const param_type& __p2) > @@ -6472,8 +6524,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > _M_initialize2(const _RealType* __ints, _RealType __den); > > std::vector<_RealType> _M_int; > - std::vector<double> _M_den; > - std::vector<double> _M_cp; > + std::vector<_StorageType> _M_den; > + std::vector<_StorageType> _M_cp; > > template<typename _RealType1, typename _CharT, typename _Traits> > friend std::basic_ostream<_CharT, _Traits>& > @@ -6520,28 +6572,17 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > /** > * @brief Returns a vector of the intervals. > */ > - std::vector<_RealType> > + std::vector<result_type> > intervals() const > - { > - if (_M_param._M_int.empty()) > - { > - std::vector<_RealType> __tmp(2); > - __tmp[1] = _RealType(1); > - return __tmp; > - } > - else > - return _M_param._M_int; > - } > + { return _M_param.intervals(); } > > /** > * @brief Returns a vector of the probability densities. > */ > - std::vector<double> > + [[__gnu__::__always_inline__]] > + std::vector<_RealType> > densities() const > - { > - return _M_param._M_den.empty() > - ? std::vector<double>(1, 1.0) : _M_param._M_den; > - } > + { return _M_param.densities(); } > > /** > * @brief Returns the parameter set of the distribution. > @@ -6694,6 +6735,12 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > { > static_assert(std::is_floating_point<_RealType>::value, > "result_type must be a floating point type"); > + using _StorageType > +#ifdef _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES > + = _RealType; > +#else > + = typename > __detail::__piecewise_distributions_storage<_RealType>::type; > +#endif > > public: > /** The type of the range of the distribution. */ > @@ -6725,7 +6772,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > param_type(const param_type&) = default; > param_type& operator=(const param_type&) = default; > > - std::vector<_RealType> > + std::vector<result_type> > intervals() const > { > if (_M_int.empty()) > @@ -6738,9 +6785,28 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > return _M_int; > } > > - std::vector<double> > + // _GLIBCXX_RESOLVE_LIB_DEFECTS > + // 1439. Return from densities() functions? > + [[__gnu__::__abi_tag__("__rt")]] > + std::vector<result_type> > densities() const > - { return _M_den.empty() ? std::vector<double>(2, 1.0) : _M_den; } > + { > +#pragma GCC diagnostic push > +#pragma GCC diagnostic ignored "-Wc++17-extensions" > + if (_M_den.empty()) > + return std::vector<_RealType>(2, _RealType(1)); > + else if constexpr (is_same<_RealType, _StorageType>::value) > + return _M_den; > + else > + { > + std::vector<_RealType> __res; > + __res.reserve(_M_den.size()); > + for (_RealType __v : _M_den) > + __res.push_back(__v); > + return __res; > + } > +#pragma GCC diagnostic pop > + } > > friend bool > operator==(const param_type& __p1, const param_type& __p2) > @@ -6760,9 +6826,9 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > _M_initialize2(const _RealType* __ints, const _RealType* __dens); > > std::vector<_RealType> _M_int; > - std::vector<double> _M_den; > - std::vector<double> _M_cp; > - std::vector<double> _M_m; > + std::vector<_StorageType> _M_den; > + std::vector<_StorageType> _M_cp; > + std::vector<_StorageType> _M_m; > > template<typename _RealType1, typename _CharT, typename _Traits> > friend std::basic_ostream<_CharT, _Traits>& > @@ -6809,29 +6875,18 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > /** > * @brief Return the intervals of the distribution. > */ > - std::vector<_RealType> > + std::vector<result_type> > intervals() const > - { > - if (_M_param._M_int.empty()) > - { > - std::vector<_RealType> __tmp(2); > - __tmp[1] = _RealType(1); > - return __tmp; > - } > - else > - return _M_param._M_int; > - } > + { return _M_param.intervals(); } > > /** > * @brief Return a vector of the probability densities of the > * distribution. > */ > - std::vector<double> > + [[__gnu__::__always_inline__]] > + std::vector<result_type> > densities() const > - { > - return _M_param._M_den.empty() > - ? std::vector<double>(2, 1.0) : _M_param._M_den; > - } > + { return _M_param.densities(); } > > /** > * @brief Returns the parameter set of the distribution. > diff --git a/libstdc++-v3/include/bits/random.tcc > b/libstdc++-v3/include/bits/random.tcc > index e581f912764..f0e2a0d5849 100644 > --- a/libstdc++-v3/include/bits/random.tcc > +++ b/libstdc++-v3/include/bits/random.tcc > @@ -3164,6 +3164,8 @@ namespace __detail > const piecewise_constant_distribution<_RealType>& __x) > { > using __ios_base = typename basic_ostream<_CharT, > _Traits>::ios_base; > + using _StorageType > + = typename > piecewise_constant_distribution<_RealType>::_StorageType; > > const typename __ios_base::fmtflags __flags = __os.flags(); > const _CharT __fill = __os.fill(); > @@ -3199,6 +3201,8 @@ namespace __detail > piecewise_constant_distribution<_RealType>& __x) > { > using __ios_base = typename basic_istream<_CharT, > _Traits>::ios_base; > + using _StorageType > + = typename > piecewise_constant_distribution<_RealType>::_StorageType; > > const typename __ios_base::fmtflags __flags = __is.flags(); > __is.flags(__ios_base::dec | __ios_base::skipws); > @@ -3209,7 +3213,7 @@ namespace __detail > std::vector<_RealType> __int_vec; > if (__detail::__extract_params(__is, __int_vec, __n + 1)) > { > - std::vector<double> __den_vec; > + std::vector<_StorageType> __den_vec; > if (__detail::__extract_params(__is, __den_vec, __n)) > { > __x.param({ __int_vec.begin(), __int_vec.end(), > @@ -3466,6 +3470,8 @@ namespace __detail > piecewise_linear_distribution<_RealType>& __x) > { > using __ios_base = typename basic_istream<_CharT, > _Traits>::ios_base; > + using _StorageType > + = typename piecewise_linear_distribution<_RealType>::_StorageType; > > const typename __ios_base::fmtflags __flags = __is.flags(); > __is.flags(__ios_base::dec | __ios_base::skipws); > @@ -3476,7 +3482,7 @@ namespace __detail > vector<_RealType> __int_vec; > if (__detail::__extract_params(__is, __int_vec, __n + 1)) > { > - vector<double> __den_vec; > + vector<_StorageType> __den_vec; > if (__detail::__extract_params(__is, __den_vec, __n + 1)) > { > __x.param({ __int_vec.begin(), __int_vec.end(), > diff --git > a/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/operators/accessors.cc > b/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/operators/accessors.cc > new file mode 100644 > index 00000000000..6d466d83cd5 > --- /dev/null > +++ > b/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/operators/accessors.cc > @@ -0,0 +1,73 @@ > +// { dg-do run { target c++11 } } > +// { dg-require-cstdint "" } > + > +#include <random> > +#include <testsuite_hooks.h> > + > +template<typename RealType> > +void > +test_exact() > +{ > + RealType x[6] = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0}; > + RealType wt[5] = {0.5, 1.0, 3.5, 2.5, 0.5}; > + > + std::piecewise_constant_distribution<RealType> > + u(std::begin(x), std::end(x), wt); > + > + const std::vector<RealType>& interval = u.intervals(); > + VERIFY( interval.size() == 6 ); > + VERIFY( interval[0] == RealType(0.0) ); > + VERIFY( interval[5] == RealType(5.0) ); > + > + const std::vector<RealType>& density = u.densities(); > + VERIFY( density.size() == 5 ); > + VERIFY( density[0] == RealType(0.5 / 8.0) ); > + VERIFY( density[1] == RealType(1.0 / 8.0) ); > + VERIFY( density[2] == RealType(3.5 / 8.0) ); > + VERIFY( density[3] == RealType(2.5 / 8.0) ); > + VERIFY( density[4] == RealType(0.5 / 8.0) ); > +} > + > +template<typename RealType> > +void > +test_precision_depended() > +{ > + constexpr bool preserved > +#ifdef _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES > + = true; > +#else > + = sizeof(RealType) <= sizeof(double); > +#endif > + > + RealType x[3]{0.0, 0.5, 1.0}; > + constexpr RealType step > + = std::numeric_limits<RealType>::epsilon(); > + RealType wt[2]{RealType(1) - step, RealType(1) + step}; > + > + std::piecewise_constant_distribution<RealType> > + u(std::begin(x), std::end(x), wt); > + > + const std::vector<RealType>& interval = u.intervals(); > + VERIFY( interval.size() == 3 ); > + VERIFY( interval[0] == RealType(0.0) ); > + VERIFY( interval[2] == RealType(1.0) ); > + > + const std::vector<RealType>& density = u.densities(); > + VERIFY( density.size() == 2 ); > + VERIFY( density[0] == (preserved ? wt[0] : RealType(1)) ); > + VERIFY( density[1] == (preserved ? wt[1] : RealType(1)) ); > +} > + > +int main() > +{ > + using namespace __gnu_test; > + test_exact<float>(); > + test_exact<double>(); > + test_exact<long double>(); > + > + test_precision_depended<float>(); > + test_precision_depended<double>(); > + test_precision_depended<long double>(); > + > + return 0; > +} > diff --git > a/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/operators/accessors_exact.cc > b/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/operators/accessors_exact.cc > new file mode 100644 > index 00000000000..469ed3fac46 > --- /dev/null > +++ > b/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/operators/accessors_exact.cc > @@ -0,0 +1,5 @@ > +// { dg-options "-D_GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES" } > +// { dg-do run { target c++11 } } > +// { dg-require-cstdint "" } > +#include "accessors.cc" > + > diff --git > a/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/operators/accessors.cc > b/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/operators/accessors.cc > new file mode 100644 > index 00000000000..23d10696fdb > --- /dev/null > +++ > b/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/operators/accessors.cc > @@ -0,0 +1,75 @@ > +// { dg-do run { target c++11 } } > +// { dg-require-cstdint "" } > + > +#include <random> > +#include <testsuite_hooks.h> > + > +template<typename RealType> > +void > +test_exact() > +{ > + RealType x[6] = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0}; > + RealType wt[6] = {0.0, 1.0, 1.0, 6.0, -1.0, 2.0}; > + > + std::piecewise_linear_distribution<RealType> > + u(std::begin(x), std::end(x), wt); > + > + const std::vector<RealType>& interval = u.intervals(); > + VERIFY( interval.size() == 6 ); > + VERIFY( interval[0] == RealType(0.0) ); > + VERIFY( interval[5] == RealType(5.0) ); > + > + const std::vector<RealType>& density = u.densities(); > + VERIFY( density.size() == 6 ); > + VERIFY( density[0] == RealType(0.0 / 8.0) ); > + VERIFY( density[1] == RealType(1.0 / 8.0) ); > + VERIFY( density[2] == RealType(1.0 / 8.0) ); > + VERIFY( density[3] == RealType(6.0 / 8.0) ); > + VERIFY( density[4] == RealType(-1.0 / 8.0) ); > + VERIFY( density[5] == RealType(2.0 / 8.0) ); > +} > + > +template<typename RealType> > +void > +test_precision_depended() > +{ > + constexpr bool preserved > +#ifdef _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES > + = true; > +#else > + = sizeof(RealType) <= sizeof(double); > +#endif > + > + RealType x[3]{0.0, 0.5, 1.0}; > + constexpr RealType step > + = std::numeric_limits<RealType>::epsilon() * 2; > + RealType wt[3]{RealType(1) - step, RealType(1), RealType(1) + step}; > + > + std::piecewise_linear_distribution<RealType> > + u(std::begin(x), std::end(x), wt); > + > + const std::vector<RealType>& interval = u.intervals(); > + VERIFY( interval.size() == 3 ); > + VERIFY( interval[0] == RealType(0.0) ); > + VERIFY( interval[2] == RealType(1.0) ); > + > + const std::vector<RealType>& density = u.densities(); > + VERIFY( density.size() == 3 ); > + VERIFY( density[0] == (preserved ? wt[0] : RealType(1)) ); > + VERIFY( density[1] == RealType(1) ); > + VERIFY( density[2] == (preserved ? wt[2] : RealType(1)) ); > +} > + > +int main() > +{ > + using namespace __gnu_test; > + test_exact<float>(); > + test_exact<double>(); > + test_exact<long double>(); > + > + test_precision_depended<float>(); > + test_precision_depended<double>(); > + test_precision_depended<long double>(); > + > + return 0; > +} > diff --git > a/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/operators/accessors_exact.cc > b/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/operators/accessors_exact.cc > new file mode 100644 > index 00000000000..469ed3fac46 > --- /dev/null > +++ > b/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/operators/accessors_exact.cc > @@ -0,0 +1,5 @@ > +// { dg-options "-D_GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES" } > +// { dg-do run { target c++11 } } > +// { dg-require-cstdint "" } > +#include "accessors.cc" > + > -- > 2.54.0 > >
