[PATCH v3] libstdc++: Fix reserve of size_t(-1) elements in piecewise_constant_distribution. [PR113761]
Jonathan Wakely
jwakely@redhat.com
Wed May 13 16:32:01 GMT 2026
On Wed, 13 May 2026 at 16:52 +0200, Tomasz Kamiński wrote:
>The piecewise_constant_distribution constructor from std::initializer_list il,
>unconditionally reserve _M_den for il.size()-1 elements. In case when the il.size()
>was zero, this led to unsigned overflow, and attempt to allocate size_t(-1)
>elements.
>
>This patch addresses above, by refactoring the constructors of param_type for
>both piecewise_constant_distribution and piecewise_linear_distribution, to
>exit early (and do not populate internal vectors) if number of intervals range is
>smaller than two. For the constructor accepting pair of iterators, this is done
>by checking result of __detail::__load_first2, that extracts up to two elements,
>and returns false, if less than two is found.
>
>Furthermore, we if the number of intervals is equal to two (for iterator __bbegin
>is at __bend after __load_first2), we store densities value on stack, and call
>newly introduced an _M_initialize2 helper, that does not populate internal vector
>if __ints and __dens values correspond to default configuration.
>
>With both of above changes, we no longer populate _M_int and _M_den with default
>values, and corresponding code that clears them in _M_initialize is not necessary.
>This avoids any unnecessary memory allocators.
>
>For constructor accepting two iterators, we reserve required space in _M_int vector,
>if the iterators are forward (or model sized_sentinel in C++20). The _M_den
>initialization is performed afterwards, so _M_int size is already determined
>(even for input iterators) and it can be used for call to reserve.
>
>Finally, the _M_initialize members are renamed to _M_configure, so the new
>implementation that skips the check, is not used by TU compiler will other
>that would invoke it with empty vector, and thus retrigger the issue.
>
> PR libstdc++/113761
>
>libstdc++-v3/ChangeLog:
>
> * include/bits/random.h
> (piecewise_constant_distribution::param_type::_M_initialize)
> (piecewise_linear_distribution::param_type::_M_initialize): Remove.
> (piecewise_constant_distribution::param_type::_M_configure)
> (piecewise_linear_distribution::param_type::_M_configure): Define.
> (piecewise_constant_distribution::param_type::_M_initialize2)
> (piecewise_linear_distribution::param_type::_M_initialize2): Declare.
> * include/bits/random.tcc (__detail::__load_first2): Define.
> (piecewise_constant_distribution::param_type::_M_initialize)
> (piecewise_linear_distribution::param_type::_M_initialize):
> Rename to...
> (piecewise_constant_distribution::param_type::_M_configure)
> (piecewise_linear_distribution::param_type::_M_configure):
> Renamed implementation of _M_initialize, that removes checks for
> default values.
> (piecewise_constant_distribution::param_type::_M_initialize2)
> (piecewise_linear_distribution::param_type::_M_initialize2): Define.
> (piecewise_constant_distribution::param_type::param_type)
> (piecewise_linear_distribution::param_type::param_type):
> Exit early for less that two intervals. Use _M_initialize2 to handle
> two intervals case. Reserve _M_int for iterators case.
> * testsuite/26_numerics/random/piecewise_constant_distribution/cons/range.cc:
> Test input and forward iterators, in addition to random_access ones.
> * testsuite/26_numerics/random/piecewise_linear_distribution/cons/range.cc:
> Likewise.
> * testsuite/26_numerics/random/piecewise_constant_distribution/cons/fallback.cc:
> New test.
> * testsuite/26_numerics/random/piecewise_linear_distribution/cons/fallback.cc:
> New test.
>---
>v2 changes:
>- rename _M_intialize to _M_configure to avoid ABI break, I used configure
> as name, because we call it with already initialized _M_int and _M_den
>- updated commit description to fix the typos and unclear sentences
>- added explanation for rename to commit description
>- moved * to type in _M_initialize2 signatures
>- used for-each to initialize entities for picewise_linear_distribution
> constructor from initializer_list
>I haven't updated the copying from __wbegin to use _M_assign, as the
>conditions need to look at reference type (if it is _Real), so we add
>complexity, without real benefit.
>
>Testing on x86_64-linux. *picewise* test passed again, so didn't make
>new typos. OK for trunk when all test passes?
OK
> libstdc++-v3/include/bits/random.h | 10 +-
> libstdc++-v3/include/bits/random.tcc | 224 ++++++++++++++----
> .../cons/fallback.cc | 108 +++++++++
> .../cons/range.cc | 17 +-
> .../cons/fallback.cc | 127 ++++++++++
> .../cons/range.cc | 17 +-
> 6 files changed, 439 insertions(+), 64 deletions(-)
> create mode 100644 libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/fallback.cc
> create mode 100644 libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/fallback.cc
>
>diff --git a/libstdc++-v3/include/bits/random.h b/libstdc++-v3/include/bits/random.h
>index 3fda69c4399..5d037465d3c 100644
>--- a/libstdc++-v3/include/bits/random.h
>+++ b/libstdc++-v3/include/bits/random.h
>@@ -6466,7 +6466,10 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
>
> private:
> void
>- _M_initialize();
>+ _M_configure();
>+
>+ void
>+ _M_initialize2(const _RealType* __ints, _RealType __den);
>
> std::vector<_RealType> _M_int;
> std::vector<double> _M_den;
>@@ -6746,7 +6749,10 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
>
> private:
> void
>- _M_initialize();
>+ _M_configure();
>+
>+ void
>+ _M_initialize2(const _RealType* __ints, const _RealType* __dens);
>
> std::vector<_RealType> _M_int;
> std::vector<double> _M_den;
>diff --git a/libstdc++-v3/include/bits/random.tcc b/libstdc++-v3/include/bits/random.tcc
>index 4475e365c2d..80b51d099fa 100644
>--- a/libstdc++-v3/include/bits/random.tcc
>+++ b/libstdc++-v3/include/bits/random.tcc
>@@ -2945,18 +2945,8 @@ namespace __detail
> template<typename _RealType>
> void
> piecewise_constant_distribution<_RealType>::param_type::
>- _M_initialize()
>+ _M_configure()
> {
>- if (_M_int.size() < 2
>- || (_M_int.size() == 2
>- && _M_int[0] == _RealType(0)
>- && _M_int[1] == _RealType(1)))
>- {
>- _M_int.clear();
>- _M_den.clear();
>- return;
>- }
>-
> const double __sum = std::accumulate(_M_den.begin(),
> _M_den.end(), 0.0);
> __glibcxx_assert(__sum > 0);
>@@ -2975,6 +2965,46 @@ namespace __detail
> _M_den[__k] /= _M_int[__k + 1] - _M_int[__k];
> }
>
>+ template<typename _RealType>
>+ void
>+ piecewise_constant_distribution<_RealType>::param_type::
>+ _M_initialize2(const _RealType* __ints, _RealType __den)
>+ {
>+ if (__ints[0] == _RealType(0) && __ints[1] == _RealType(1))
>+ return;
>+
>+ _M_int.reserve(2);
>+ _M_int.push_back(__ints[0]);
>+ _M_int.push_back(__ints[1]);
>+
>+ _M_den.reserve(1);
>+ _M_den.push_back(__den);
>+ _M_configure();
>+ }
>+
>+namespace __detail
>+{
>+ template<typename _InputIterator, typename _RealType>
>+ bool
>+ __load_first2(_InputIterator& __first, _InputIterator __last,
>+ _RealType* __out)
>+ {
>+ if (__first == __last)
>+ return false;
>+
>+ *__out = *__first;
>+ ++__first;
>+ if (__first == __last)
>+ return false;
>+
>+ ++__out;
>+ *__out = *__first;
>+ ++__first;
>+ return true;
>+ }
>+} // namespace __detail
>+
>+
> template<typename _RealType>
> template<typename _InputIteratorB, typename _InputIteratorW>
> piecewise_constant_distribution<_RealType>::param_type::
>@@ -2983,21 +3013,39 @@ namespace __detail
> _InputIteratorW __wbegin)
> : _M_int(), _M_den(), _M_cp()
> {
>- if (__bbegin != __bend)
>- {
>- for (;;)
>- {
>- _M_int.push_back(*__bbegin);
>- ++__bbegin;
>- if (__bbegin == __bend)
>- break;
>+ _RealType __ints[2];
>+ if (!__detail::__load_first2(__bbegin, __bend, __ints))
>+ return;
>
>- _M_den.push_back(*__wbegin);
>- ++__wbegin;
>- }
>+ if (__bbegin == __bend)
>+ {
>+ _M_initialize2(__ints, *__wbegin);
>+ return;
> }
>
>- _M_initialize();
>+#if __glibcxx_concepts // C++ >= C++20
>+ if constexpr (sized_sentinel_for<_InputIteratorB, _InputIteratorB>
>+ || forward_iterator<_InputIteratorB>)
>+ _M_int.reserve(2 + size_t(ranges::distance(__bbegin, __bend)));
>+#else
>+#pragma GCC diagnostic push
>+#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
>+ if constexpr (is_convertible<__iter_category_t<_InputIteratorB>,
>+ forward_iterator_tag>::value)
>+ _M_int.reserve(2 + size_t(std::distance(__bbegin, __bend)));
>+#pragma GCC diagnostic pop
>+#endif
>+
>+ _M_int.push_back(__ints[0]);
>+ _M_int.push_back(__ints[1]);
>+ for (; __bbegin != __bend; ++__bbegin)
>+ _M_int.push_back(*__bbegin);
>+
>+ _M_den.reserve(_M_int.size() - 1);
>+ for (size_t __k = 0; __k < _M_int.size() - 1; (void)++__k, ++__wbegin)
>+ _M_den.push_back(*__wbegin);
>+
>+ _M_configure();
> }
>
> template<typename _RealType>
>@@ -3006,15 +3054,23 @@ namespace __detail
> param_type(initializer_list<_RealType> __bl, _Func __fw)
> : _M_int(), _M_den(), _M_cp()
> {
>- _M_int.reserve(__bl.size());
>- for (auto __biter = __bl.begin(); __biter != __bl.end(); ++__biter)
>- _M_int.push_back(*__biter);
>+ if (__bl.size() < 2)
>+ return;
>
>+ if (__bl.size() == 2)
>+ {
>+ const _RealType *__ints = __bl.begin();
>+ _RealType __den = __fw(0.5 * (__ints[1] + __ints[0]));
>+ _M_initialize2(__ints, __den);
>+ return;
>+ }
>+
>+ _M_int = __bl;
> _M_den.reserve(_M_int.size() - 1);
> for (size_t __k = 0; __k < _M_int.size() - 1; ++__k)
> _M_den.push_back(__fw(0.5 * (_M_int[__k + 1] + _M_int[__k])));
>
>- _M_initialize();
>+ _M_configure();
> }
>
> template<typename _RealType>
>@@ -3025,6 +3081,13 @@ namespace __detail
> {
> const size_t __n = __nw == 0 ? 1 : __nw;
> const _RealType __delta = (__xmax - __xmin) / __n;
>+ if (__n == 1)
>+ {
>+ _RealType __ints[2] = { __xmin, __xmin + __delta };
>+ _RealType __den = __fw(__xmin * 0.5 * __delta);
>+ _M_initialize2(__ints, __den);
>+ return;
>+ }
>
> _M_int.reserve(__n + 1);
> for (size_t __k = 0; __k <= __nw; ++__k)
>@@ -3034,7 +3097,7 @@ namespace __detail
> for (size_t __k = 0; __k < __nw; ++__k)
> _M_den.push_back(__fw(_M_int[__k] + 0.5 * __delta));
>
>- _M_initialize();
>+ _M_configure();
> }
>
> template<typename _RealType>
>@@ -3159,19 +3222,8 @@ namespace __detail
> template<typename _RealType>
> void
> piecewise_linear_distribution<_RealType>::param_type::
>- _M_initialize()
>+ _M_configure()
> {
>- if (_M_int.size() < 2
>- || (_M_int.size() == 2
>- && _M_int[0] == _RealType(0)
>- && _M_int[1] == _RealType(1)
>- && _M_den[0] == _M_den[1]))
>- {
>- _M_int.clear();
>- _M_den.clear();
>- return;
>- }
>-
> double __sum = 0.0;
> _M_cp.reserve(_M_int.size() - 1);
> _M_m.reserve(_M_int.size() - 1);
>@@ -3194,7 +3246,27 @@ namespace __detail
>
> // Make sure the last cumulative probablility is one.
> _M_cp[_M_cp.size() - 1] = 1.0;
>- }
>+ }
>+
>+ template<typename _RealType>
>+ void
>+ piecewise_linear_distribution<_RealType>::param_type::
>+ _M_initialize2(const _RealType* __ints, const _RealType* __dens)
>+ {
>+ if (__ints[0] == _RealType(0)
>+ && __ints[1] == _RealType(1)
>+ && __dens[0] == __dens[1])
>+ return;
>+
>+ _M_int.reserve(2);
>+ _M_int.push_back(__ints[0]);
>+ _M_int.push_back(__ints[1]);
>+
>+ _M_den.reserve(2);
>+ _M_den.push_back(__dens[0]);
>+ _M_den.push_back(__dens[1]);
>+ _M_configure();
>+ }
>
> template<typename _RealType>
> template<typename _InputIteratorB, typename _InputIteratorW>
>@@ -3204,13 +3276,43 @@ namespace __detail
> _InputIteratorW __wbegin)
> : _M_int(), _M_den(), _M_cp(), _M_m()
> {
>- for (; __bbegin != __bend; ++__bbegin, (void) ++__wbegin)
>+ _RealType __ints[2];
>+ if (!__detail::__load_first2(__bbegin, __bend, __ints))
>+ return;
>+
>+ if (__bbegin == __bend)
> {
>- _M_int.push_back(*__bbegin);
>- _M_den.push_back(*__wbegin);
>+ _RealType __dens[2];
>+ __dens[0] = *__wbegin;
>+ ++__wbegin;
>+ __dens[1] = *__wbegin;
>+ _M_initialize2(__ints, __dens);
>+ return;
> }
>
>- _M_initialize();
>+#if __glibcxx_concepts // C++ >= C++20
>+ if constexpr (sized_sentinel_for<_InputIteratorB, _InputIteratorB>
>+ || forward_iterator<_InputIteratorB>)
>+ _M_int.reserve(2 + size_t(ranges::distance(__bbegin, __bend)));
>+#else
>+#pragma GCC diagnostic push
>+#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
>+ if constexpr (is_convertible<__iter_category_t<_InputIteratorB>,
>+ forward_iterator_tag>::value)
>+ _M_int.reserve(2 + size_t(std::distance(__bbegin, __bend)));
>+#pragma GCC diagnostic pop
>+#endif
>+
>+ _M_int.push_back(__ints[0]);
>+ _M_int.push_back(__ints[1]);
>+ for (; __bbegin != __bend; ++__bbegin)
>+ _M_int.push_back(*__bbegin);
>+
>+ _M_den.reserve(_M_int.size());
>+ for (size_t __i = 0; __i < _M_int.size(); (void)++__i, ++__wbegin)
>+ _M_den.push_back(*__wbegin);
>+
>+ _M_configure();
> }
>
> template<typename _RealType>
>@@ -3219,15 +3321,24 @@ namespace __detail
> param_type(initializer_list<_RealType> __bl, _Func __fw)
> : _M_int(), _M_den(), _M_cp(), _M_m()
> {
>- _M_int.reserve(__bl.size());
>- _M_den.reserve(__bl.size());
>- for (auto __biter = __bl.begin(); __biter != __bl.end(); ++__biter)
>+ if (__bl.size() < 2)
>+ return;
>+
>+ if (__bl.size() == 2)
> {
>- _M_int.push_back(*__biter);
>- _M_den.push_back(__fw(*__biter));
>+ const _RealType *__ints = __bl.begin();
>+ _RealType __den[2];
>+ __den[0] = __fw(__ints[0]);
>+ __den[1] = __fw(__ints[1]);
>+ _M_initialize2(__ints, __den);
>+ return;
> }
>
>- _M_initialize();
>+ _M_int = __bl;
>+ _M_den.reserve(__bl.size());
>+ for (_RealType __b : __bl)
>+ _M_den.push_back(__fw(__b));
>+ _M_configure();
> }
>
> template<typename _RealType>
>@@ -3238,6 +3349,15 @@ namespace __detail
> {
> const size_t __n = __nw == 0 ? 1 : __nw;
> const _RealType __delta = (__xmax - __xmin) / __n;
>+ if (__n == 1)
>+ {
>+ _RealType __ints[2] = { __xmin, __xmin + __delta };
>+ _RealType __dens[2];
>+ __dens[0] = __fw(__ints[0]);
>+ __dens[1] = __fw(__ints[1]);
>+ _M_initialize2(__ints, __dens);
>+ return;
>+ }
>
> _M_int.reserve(__n + 1);
> _M_den.reserve(__n + 1);
>@@ -3247,7 +3367,7 @@ namespace __detail
> _M_den.push_back(__fw(_M_int[__k] + __delta));
> }
>
>- _M_initialize();
>+ _M_configure();
> }
>
> template<typename _RealType>
>diff --git a/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/fallback.cc b/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/fallback.cc
>new file mode 100644
>index 00000000000..e03a1e187a7
>--- /dev/null
>+++ b/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/fallback.cc
>@@ -0,0 +1,108 @@
>+// { dg-do run { target c++11 } }
>+// { dg-require-cstdint "" }
>+
>+#include <random>
>+#include <testsuite_hooks.h>
>+#include <testsuite_iterators.h>
>+
>+using dist = std::piecewise_linear_distribution<>;
>+
>+template<typename... Args>
>+bool
>+is_default(Args&&... args)
>+{
>+ std::piecewise_constant_distribution<> u(std::forward<Args>(args)...);
>+
>+ std::vector<double> ints = u.intervals();
>+ if (ints.size() != 2 || ints[0] != 0.0 || ints[1] != 1.0)
>+ return false;
>+
>+ std::vector<double> dens = u.densities();
>+ if (dens.size() != 1 || dens[0] != 1.0)
>+ return false;
>+
>+ return true;
>+}
>+
>+template<template<typename> class Range>
>+void
>+test_it_pair()
>+{
>+ double wt[2];
>+ double x[3];
>+
>+ Range<double> r0(x, x);
>+ VERIFY( is_default(r0.begin(), r0.end(), wt) );
>+
>+ x[0] = 4.2;
>+ Range<double> r1a(x, x+1);
>+ VERIFY( is_default(r1a.begin(), r1a.end(), wt) );
>+
>+ x[0] = 0.0;
>+ Range<double> r1b(x, x+1);
>+ VERIFY( is_default(r1b.begin(), r1b.end(), wt) );
>+
>+ x[1] = 1.0;
>+ wt[0] = 13.0;
>+ Range<double> r2a(x, x+2);
>+ VERIFY( is_default(r2a.begin(), r2a.end(), wt) );
>+
>+ wt[0] = 4.2;
>+ Range<double> r2b(x, x+2);
>+ VERIFY( is_default(r2b.begin(), r2b.end(), wt) );
>+
>+ x[1] = 0.5;
>+ Range<double> r2c(x, x+2);
>+ VERIFY( !is_default(r2c.begin(), r2c.end(), wt) );
>+
>+ x[2] = 1.0;
>+ wt[1] = 2.0;
>+ Range<double> r3(x, x+3);
>+ VERIFY( !is_default(r3.begin(), r3.end(), wt) );
>+}
>+
>+void test_init_list()
>+{
>+ auto c = [](double x) { return 10; };
>+ VERIFY( is_default(std::initializer_list<double>{}, c) );
>+ VERIFY( is_default(std::initializer_list<double>{4.2}, c) );
>+ VERIFY( is_default(std::initializer_list<double>{0.0, 1.0}, c) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 0.5}, c) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 0.5, 1.0}, c) );
>+
>+ auto rel = [](double x) { return x; };
>+ VERIFY( is_default(std::initializer_list<double>{}, rel) );
>+ VERIFY( is_default(std::initializer_list<double>{4.2}, rel) );
>+ VERIFY( is_default(std::initializer_list<double>{0.0, 1.0}, rel) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 0.5}, rel) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 0.5, 1.0}, rel) );
>+}
>+
>+void test_xbound()
>+{
>+ auto c = [](double x) { return 10; };
>+ VERIFY( is_default(0, 0.0, 1.0, c) );
>+ VERIFY( !is_default(0, 0.0, 0.5, c) );
>+ VERIFY( is_default(1, 0.0, 1.0, c) );
>+ VERIFY( !is_default(1, 0.0, 0.5, c) );
>+ VERIFY( !is_default(2, 0.0, 1.0, c) );
>+
>+ auto rel = [](double x) { return x; };
>+ VERIFY( is_default(0, 0.0, 1.0, rel) );
>+ VERIFY( !is_default(0, 0.0, 0.5, rel) );
>+ VERIFY( is_default(1, 0.0, 1.0, rel) );
>+ VERIFY( !is_default(1, 0.0, 0.5, rel) );
>+ VERIFY( !is_default(2, 0.0, 1.0, rel) );
>+}
>+
>+int main()
>+{
>+ using namespace __gnu_test;
>+ test_it_pair<input_container>();
>+ test_it_pair<forward_container>();
>+ test_it_pair<random_access_container>();
>+
>+ test_init_list();
>+ test_xbound();
>+ return 0;
>+}
>diff --git a/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/range.cc b/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/range.cc
>index 3714e460391..4bfa20ea3bb 100644
>--- a/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/range.cc
>+++ b/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/range.cc
>@@ -25,13 +25,17 @@
>
> #include <random>
> #include <testsuite_hooks.h>
>+#include <testsuite_iterators.h>
>
>+template<template<typename> class Range>
> void
>-test01()
>+test_it_pair()
> {
>- std::vector<double> x = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0};
>- std::vector<double> wt = {0.5, 1.0, 2.5, 1.5, 0.5};
>- std::piecewise_constant_distribution<> u(x.begin(), x.end(), wt.begin());
>+ double x[6] = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0};
>+ double wt[5] = {0.5, 1.0, 2.5, 1.5, 0.5};
>+
>+ Range<double> r(x, x+6);
>+ std::piecewise_constant_distribution<> u(r.begin(), r.end(), wt);
> std::vector<double> interval = u.intervals();
> std::vector<double> density = u.densities();
> VERIFY( interval.size() == 6 );
>@@ -44,6 +48,9 @@ test01()
>
> int main()
> {
>- test01();
>+ using namespace __gnu_test;
>+ test_it_pair<input_container>();
>+ test_it_pair<forward_container>();
>+ test_it_pair<random_access_container>();
> return 0;
> }
>diff --git a/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/fallback.cc b/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/fallback.cc
>new file mode 100644
>index 00000000000..b2e6ca65123
>--- /dev/null
>+++ b/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/fallback.cc
>@@ -0,0 +1,127 @@
>+// { dg-do run { target c++11 } }
>+// { dg-require-cstdint "" }
>+
>+#include <random>
>+#include <testsuite_hooks.h>
>+#include <testsuite_iterators.h>
>+
>+using dist = std::piecewise_linear_distribution<>;
>+
>+template<typename... Args>
>+bool
>+is_default(Args&&... args)
>+{
>+ std::piecewise_linear_distribution<> u(std::forward<Args>(args)...);
>+
>+ std::vector<double> ints = u.intervals();
>+ if (ints.size() != 2 || ints[0] != 0.0 || ints[1] != 1.0)
>+ return false;
>+
>+ std::vector<double> dens = u.densities();
>+ if (dens.size() != 2 || dens[0] != 1.0 || dens[1] != 1.0)
>+ return false;
>+
>+ return true;
>+}
>+
>+template<template<typename> class Range>
>+void
>+test_it_pair()
>+{
>+ double wt[3];
>+ double x[3];
>+
>+ Range<double> r0(x, x);
>+ VERIFY( is_default(r0.begin(), r0.end(), wt) );
>+
>+ x[0] = 4.2;
>+ Range<double> r1a(x, x+1);
>+ VERIFY( is_default(r1a.begin(), r1a.end(), wt) );
>+
>+ x[0] = 0.0;
>+ Range<double> r1b(x, x+1);
>+ VERIFY( is_default(r1b.begin(), r1b.end(), wt) );
>+
>+ x[1] = 1.0;
>+ wt[0] = wt[1] = 13.0;
>+ Range<double> r2a(x, x+2);
>+ VERIFY( is_default(r2a.begin(), r2a.end(), wt) );
>+
>+ wt[0] = wt[1] = 1.0;
>+ Range<double> r2b(x, x+2);
>+ VERIFY( is_default(r2b.begin(), r2b.end(), wt) );
>+
>+ wt[1] = 2.0;
>+ Range<double> r2c(x, x+2);
>+ VERIFY( !is_default(r2c.begin(), r2c.end(), wt) );
>+
>+ x[1] = 0.5;
>+ wt[0] = wt[1] = 2.0;
>+ Range<double> r2d(x, x+2);
>+ VERIFY( !is_default(r2d.begin(), r2d.end(), wt) );
>+
>+ x[2] = 1.0;
>+ wt[2] = wt[0];
>+ Range<double> r3(x, x+3);
>+ VERIFY( !is_default(r3.begin(), r3.end(), wt) );
>+}
>+
>+void test_init_list()
>+{
>+ auto c1 = [](double x) { return 1.0; };
>+ VERIFY( is_default(std::initializer_list<double>{}, c1) );
>+ VERIFY( is_default(std::initializer_list<double>{4.2}, c1) );
>+ VERIFY( is_default(std::initializer_list<double>{0.0, 1.0}, c1) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 0.5}, c1) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 0.5, 1.0}, c1) );
>+
>+ auto c2 = [](double x) { return 4.2; };
>+ VERIFY( is_default(std::initializer_list<double>{}, c2) );
>+ VERIFY( is_default(std::initializer_list<double>{4.2}, c2) );
>+ VERIFY( is_default(std::initializer_list<double>{0.0, 1.0}, c2) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 0.5}, c2) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 0.5, 1.0}, c2) );
>+
>+ auto id = [](double x) { return x; };
>+ VERIFY( is_default(std::initializer_list<double>{}, id) );
>+ VERIFY( is_default(std::initializer_list<double>{4.2}, id) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 1.0}, id) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 0.5}, id) );
>+ VERIFY( !is_default(std::initializer_list<double>{0.0, 0.5, 1.0}, id) );
>+}
>+
>+void test_xbound()
>+{
>+ auto c1 = [](double x) { return 1.0; };
>+ VERIFY( is_default(0, 0.0, 1.0, c1) );
>+ VERIFY( !is_default(0, 0.0, 0.5, c1) );
>+ VERIFY( is_default(1, 0.0, 1.0, c1) );
>+ VERIFY( !is_default(1, 0.0, 0.5, c1) );
>+ VERIFY( !is_default(2, 0.0, 1.0, c1) );
>+
>+ auto c2 = [](double x) { return 4.2; };
>+ VERIFY( is_default(0, 0.0, 1.0, c2) );
>+ VERIFY( !is_default(0, 0.0, 0.5, c2) );
>+ VERIFY( is_default(1, 0.0, 1.0, c2) );
>+ VERIFY( !is_default(1, 0.0, 0.5, c2) );
>+ VERIFY( !is_default(2, 0.0, 1.0, c2) );
>+
>+ auto id = [](double x) { return x; };
>+ VERIFY( !is_default(0, 0.0, 1.0, id) );
>+ VERIFY( !is_default(0, 0.0, 0.5, id) );
>+ VERIFY( !is_default(1, 0.0, 1.0, id) );
>+ VERIFY( !is_default(1, 0.0, 0.5, id) );
>+ VERIFY( !is_default(2, 0.0, 1.0, id) );
>+}
>+
>+int main()
>+{
>+ using namespace __gnu_test;
>+ test_it_pair<input_container>();
>+ test_it_pair<forward_container>();
>+ test_it_pair<random_access_container>();
>+
>+ test_init_list();
>+ test_xbound();
>+ return 0;
>+}
>diff --git a/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/range.cc b/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/range.cc
>index c698e7a66e6..af979fdac42 100644
>--- a/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/range.cc
>+++ b/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/range.cc
>@@ -25,13 +25,17 @@
>
> #include <random>
> #include <testsuite_hooks.h>
>+#include <testsuite_iterators.h>
>
>+template<template<typename> class Range>
> void
>-test01()
>+test_it_pair()
> {
>- std::vector<double> x = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0};
>- std::vector<double> wt = {0.0, 1.0, 2.5, 1.5, 3.5, 0.0};
>- std::piecewise_linear_distribution<> u(x.begin(), x.end(), wt.begin());
>+ double x[] = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0};
>+ double wt[] = {0.0, 1.0, 2.5, 1.5, 3.5, 0.0};
>+
>+ Range<double> r(x, x+6);
>+ std::piecewise_linear_distribution<> u(r.begin(), r.end(), wt);
> std::vector<double> interval = u.intervals();
> std::vector<double> density = u.densities();
> VERIFY( interval.size() == 6 );
>@@ -44,6 +48,9 @@ test01()
>
> int main()
> {
>- test01();
>+ using namespace __gnu_test;
>+ test_it_pair<input_container>();
>+ test_it_pair<forward_container>();
>+ test_it_pair<random_access_container>();
> return 0;
> }
>--
>2.54.0
>
>
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