https://gcc.gnu.org/g:c638dae26f3134951e11aafe696787f83121571c
commit r17-4385-gc638dae26f3134951e11aafe696787f83121571c Author: Tomasz Kamiński <[email protected]> Date: Wed Sep 16 10:10:00 2026 +0200 libstdc++: Update underlying gamma_distribution in param() [PR123409] This updates the underlying gamma distribution in the param function by invoking the param function on the corresponding member: * _M_gd for negative_binomial_distribution, student_t_distribution; * _M_gd_x, _M_gd_y for fisher_f_distribution. The distribution_param.cc test, validates that for all distributions, constructing from or setting params results in equal distribution that produces same values. The test uses -ffloat-store for -m32, following chi_squared_distribution test for PR83833 - that is removed, as all cases are covered in new test. libstdc++-v3/ChangeLog: PR libstdc++/123409 * include/bits/random.h (negative_binomial_distribution::param) (fisher_f_distribution::param, student_t_distribution::param): Updated underlying gamma distributions, by calling param. (chi_squared_distribution::param): Use type alias and parenthesis for consistency. * testsuite/26_numerics/random/distribution_param.cc: New test. * testsuite/26_numerics/random/chi_squared_distribution/83833.cc: Removed, covered by above. Reviewed-by: Jonathan Wakely <[email protected]> Diff: --- libstdc++-v3/include/bits/random.h | 32 +++++++++--- .../random/chi_squared_distribution/83833.cc | 41 --------------- .../26_numerics/random/distribution_param.cc | 60 ++++++++++++++++++++++ 3 files changed, 86 insertions(+), 47 deletions(-) diff --git a/libstdc++-v3/include/bits/random.h b/libstdc++-v3/include/bits/random.h index cfec087f0cd2..1a2900e2b9d8 100644 --- a/libstdc++-v3/include/bits/random.h +++ b/libstdc++-v3/include/bits/random.h @@ -3559,9 +3559,10 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) param(const param_type& __param) { _M_param = __param; - typedef typename std::gamma_distribution<result_type>::param_type - param_type; - _M_gd.param(param_type{__param.n() / 2}); + + using param_type + = typename std::gamma_distribution<result_type>::param_type; + _M_gd.param(param_type(__param.n() / 2)); } /** @@ -4015,7 +4016,14 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) */ void param(const param_type& __param) - { _M_param = __param; } + { + _M_param = __param; + + using param_type + = typename std::gamma_distribution<result_type>::param_type; + _M_gd_x.param(param_type(__param.m() / 2)); + _M_gd_y.param(param_type(__param.n() / 2)); + } /** * @brief Returns the greatest lower bound value of the distribution. @@ -4244,7 +4252,13 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) */ void param(const param_type& __param) - { _M_param = __param; } + { + _M_param = __param; + + using param_type + = typename std::gamma_distribution<result_type>::param_type; + _M_gd.param(param_type(__param.n() / 2, 2)); + } /** * @brief Returns the greatest lower bound value of the distribution. @@ -5175,7 +5189,13 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) */ void param(const param_type& __param) - { _M_param = __param; } + { + _M_param = __param; + + using param_type + = typename std::gamma_distribution<double>::param_type; + _M_gd.param(param_type(__param.k(), (1.0 - __param.p()) / __param.p())); + } /** * @brief Returns the greatest lower bound value of the distribution. diff --git a/libstdc++-v3/testsuite/26_numerics/random/chi_squared_distribution/83833.cc b/libstdc++-v3/testsuite/26_numerics/random/chi_squared_distribution/83833.cc deleted file mode 100644 index 4008f7db89c9..000000000000 --- a/libstdc++-v3/testsuite/26_numerics/random/chi_squared_distribution/83833.cc +++ /dev/null @@ -1,41 +0,0 @@ -// Copyright (C) 2018-2026 Free Software Foundation, Inc. -// -// This file is part of the GNU ISO C++ Library. This library is free -// software; you can redistribute it and/or modify it under the -// terms of the GNU General Public License as published by the -// Free Software Foundation; either version 3, or (at your option) -// any later version. - -// This library is distributed in the hope that it will be useful, -// but WITHOUT ANY WARRANTY; without even the implied warranty of -// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -// GNU General Public License for more details. - -// You should have received a copy of the GNU General Public License along -// with this library; see the file COPYING3. If not see -// <http://www.gnu.org/licenses/>. - -// { dg-do run { target c++11 } } -// { dg-additional-options "-ffloat-store" { target { m68*-*-* || ia32 } } } -// { dg-require-cstdint "" } - -#include <random> -#include <testsuite_hooks.h> - -void -test01() -{ - std::default_random_engine r1, r2; - using chi = std::chi_squared_distribution<double>; - chi::param_type p(5); - chi d1(p); - chi d2; - d2.param(p); - VERIFY( d1(r1) == d2(r2) ); // PR libstdc++/83833 -} - -int -main() -{ - test01(); -} diff --git a/libstdc++-v3/testsuite/26_numerics/random/distribution_param.cc b/libstdc++-v3/testsuite/26_numerics/random/distribution_param.cc new file mode 100644 index 000000000000..d6c067662336 --- /dev/null +++ b/libstdc++-v3/testsuite/26_numerics/random/distribution_param.cc @@ -0,0 +1,60 @@ +// { dg-do run { target c++11 } } +// { dg-additional-options "-ffloat-store" { target { m68*-*-* || ia32 } } } +// { dg-require-cstdint "" } + +#include <random> +#include <testsuite_hooks.h> + +template<typename Distribution> +void +validate(Distribution&& source) +{ + const auto& params = source.param(); + + Distribution constr(params); + VERIFY( constr == source ); + + Distribution setter; + setter.param(params); + VERIFY( setter == source ); + + std::mt19937_64 e1(0x19650809ull), e2 = e1, e3 = e1; + for (int i = 0; i < 10; ++i) + { + const auto expected = source(e1); + VERIFY( constr(e2) == expected ); + VERIFY( setter(e3) == expected ); + } +} + +int main() +{ + // PR83833, PR123409 + validate(std::uniform_int_distribution<>(13, 22)); + validate(std::uniform_real_distribution<>(1.0, 9.0)); + + validate(std::bernoulli_distribution(0.478)); + validate(std::binomial_distribution<>(7, 0.334)); + validate(std::negative_binomial_distribution<>(726, 0.65)); + validate(std::geometric_distribution<>(0.545)); + + validate(std::poisson_distribution<>(6)); + validate(std::exponential_distribution<>(3)); + validate(std::gamma_distribution<>(1.1, 2.2)); + validate(std::weibull_distribution<>(1.7, 3.0)); + validate(std::extreme_value_distribution<>(-1.628, 1.628)); + + validate(std::normal_distribution<>(5.0, 2.0)); + validate(std::lognormal_distribution<>(1.67, 0.25)); + validate(std::chi_squared_distribution<>(5)); + validate(std::cauchy_distribution<>(-3, 0.25)); + validate(std::fisher_f_distribution<>(26.0, 7.0)); + validate(std::student_t_distribution<>(65.0)); + + const auto wf = [](double x) { return 1 + x; }; + validate(std::discrete_distribution<>(4, 1.2, 4.5, wf)); + validate(std::piecewise_constant_distribution<>(5, 0.5, 9, wf)); + validate(std::piecewise_linear_distribution<>(3, 1.2, 3.4, wf)); + + return 0; +}
