On Fri, May 29, 2026 at 4:53 PM Jonathan Wakely <[email protected]> wrote:
> On Wed, 27 May 2026 at 08:42 +0200, Tomasz Kamiński 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> > >struct, whose type nested typedef points to double in above two cases, > >and _Tp otherwise. The _StorageType is defined in terms of > >__piecewise_distributions_storage_t alias to above, and 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 > >__piecewise_distributions_storage_t being unconditionally defined > >as _Tp, 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) > > (__detail::__piecewise_distributions_storage_t) > > (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. > >--- > >v2: > > - removes unused _StorageType alias from operator<< > > - introduces __piecewise_distributions_storage_t alias, > > and changes commit description > >(Sending due changes to commit description). > > > >Tested on x86_64-linux. OK for trunk? > > > > .../doc/html/manual/using_macros.html | 11 ++ > > libstdc++-v3/doc/xml/manual/using.xml | 17 +++ > > libstdc++-v3/include/bits/random.h | 142 ++++++++++++------ > > libstdc++-v3/include/bits/random.tcc | 8 +- > > .../operators/accessors.cc | 73 +++++++++ > > .../operators/accessors_exact.cc | 5 + > > .../operators/accessors.cc | 75 +++++++++ > > .../operators/accessors_exact.cc | 5 + > > 8 files changed, 291 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> > > Let's rephrase this as follows (and include the magic phrase > "ABI-changing" which that page defines and uses for macros which > affect the ABI: > > Undefined by default. ABI-changing. > When defined, specializations of piecewise_constant_distribution and > piecewise_linear_distribution with a result_type of either float or > long double will manage their internal state using result_type values > (instead of double). This is required for standard conformance, but is > incompatible with the default implementation of those class templates. > > > >+ </listitem></varlistentry> > >+ > > </variablelist> > > > > </section> > >diff --git a/libstdc++-v3/include/bits/random.h > b/libstdc++-v3/include/bits/random.h > >index a0592a00763..6016a56dc21 100644 > >--- a/libstdc++-v3/include/bits/random.h > >+++ b/libstdc++-v3/include/bits/random.h > >@@ -6385,6 +6385,40 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > > { return !(__d1 == __d2); } > > #endif > > > >+ 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; }; > >+ > >+ template<> > >+ struct __piecewise_distributions_storage<float> > >+ { using type = double; }; > >+ > >+# ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT > > Is this necessary? > > Users should only instantiate the <random> distributions with float, > double, or long double. In any given translation unit, they should > only refer to piecewise_linear_distribution<long double> and not > piecewise_linear_distribution</* the other kind of long double */>. > > I suppose it's possible that they need to explicitly refer to > piecewise_linear_distribution<__ibm128> for a class data member to > ensure it has a stable definition in all TUs. > I was thinking about the internal uses in the library, where some template being explicitly instantiated with __ibm128 or __int128 (like format does) will trigger instantiation of piecewise_distributions. With the above, I do not need to concern myself with searching for such situation, however unlikely it may be. > > >+ 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 > >+ > >+ template<typename _Tp> > >+ using __piecewise_distributions_storage_t > >+ = typename __piecewise_distributions_storage<_Tp>::type; > >+#endif // _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES > >+ } > >+ > > /** > > * @brief A piecewise_constant_distribution random number distribution. > > * > >@@ -6407,6 +6441,9 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > > static_assert(std::is_floating_point<_RealType>::value, > > "result_type must be a floating point type"); > > > >+ using _StorageType > >+ = __detail::__piecewise_distributions_storage_t<_RealType>; > >+ > > public: > > /** The type of the range of the distribution. */ > > typedef _RealType result_type; > >@@ -6437,7 +6474,7 @@ _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 +6487,28 @@ _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> > > I wonder if the _GLIBCXX_USE_RESULT_TYPE_FOR_PIECEWISE_DENSITIES macro > should also control this, or a different macro. So that users who > don't want the new return type can select the old one. > > Curently we have a macro to change the _M_den and _M_cp members, but > no way to control the return type here. The abi_tag and always_inline > attributes makes them distinct functions, but it would still be a > source-breaking change for any code doing: > > std::piecewise_constant_distribution<float> dist; > vector<double> d = dist.densities(); > > Maybe that's OK? > > > 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 +6528,8 @@ _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 +6576,17 @@ _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> > > You've changed vector<_RealType> to vector<result_type> elsewhere, > should this be vector<result_type> too? > > > 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. > >@@ -6695,6 +6740,9 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) > > static_assert(std::is_floating_point<_RealType>::value, > > "result_type must be a floating point type"); > > > >+ using _StorageType > >+ = __detail::__piecewise_distributions_storage_t<_RealType>; > >+ > > public: > > /** The type of the range of the distribution. */ > > typedef _RealType result_type; > >@@ -6725,7 +6773,7 @@ _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 +6786,28 @@ _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 +6827,9 @@ _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 +6876,18 @@ _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..6c88d68d3e4 100644 > >--- a/libstdc++-v3/include/bits/random.tcc > >+++ b/libstdc++-v3/include/bits/random.tcc > >@@ -3199,6 +3199,8 @@ 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 +3211,7 @@ 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 +3468,8 @@ 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 +3480,7 @@ 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 > > > > > >
