P0935R0 Eradicating unnecessarily explicit default constructors

The param_type constructors of each random number distribution should
mirror the constructors of the distribution itself, so make the same
changes w.r.t explicit on default constructors.

	* include/bits/random.h (uniform_real_distribution::param_type)
	(normal_distribution::param_type, lognormal_distribution::param_type)
	(gamma_distribution::param_type, chi_squared_distribution::param_type)
	(cauchy_distribution::param_type, fisher_f_distribution::param_type)
	(student_t_distribution::param_type)
	(bernoulli_distribution::param_type)
	(binomial_distribution::param_type)
	(geometric_distribution::param_type)
	(negative_binomial_distribution::param_type)
	(poisson_distribution::param_type)
	(exponential_distribution::param_type)
	(weibull_distribution::param_type)
	(extreme_value_distribution::param_type): Add non-explicit default
	constructors. Remove default argument for first parameter of explicit
	constructors.
	* include/bits/uniform_int_dist.h
	(uniform_int_distribution::param_type): Likewise.
	* include/ext/random
	(beta_distribution::param_type, rice_distribution::param_type)
	(nakagami_distribution::param_type, pareto_distribution::param_type)
	(k_distribution::param_type, arcsine_distribution::param_type)
	(hoyt_distribution::param_type, triangular_distribution::param_type)
	(von_mises_distribution::param_type)
	(hypergeometric_distribution::param_type)
	(logistic_distribution::param_type)
	(uniform_inside_sphere_distribution::param_type): Likewise.
	(uniform_on_sphere_distribution::param_type): Make default constructor
	non-explicit.
	* testsuite/26_numerics/random/bernoulli_distribution/cons/default.cc:
	Test param_type for non-explicit default constructor.
	* testsuite/26_numerics/random/binomial_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/cauchy_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/chi_squared_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/discrete_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/exponential_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/extreme_value_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/fisher_f_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/gamma_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/geometric_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/lognormal_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/negative_binomial_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/normal_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/piecewise_constant_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/piecewise_linear_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/poisson_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/student_t_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/uniform_int_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/uniform_real_distribution/cons/default.cc:
	Likewise.
	* testsuite/26_numerics/random/weibull_distribution/cons/default.cc:
	Likewise.
	* testsuite/ext/random/arcsine_distribution/cons/default.cc: Likewise.
	* testsuite/ext/random/beta_distribution/cons/default.cc: Likewise.
	* testsuite/ext/random/hoyt_distribution/cons/default.cc: Likewise.
	* testsuite/ext/random/hypergeometric_distribution/cons/default.cc:
	Likewise.
	* testsuite/ext/random/k_distribution/cons/default.cc: Likewise.
	* testsuite/ext/random/logistic_distribution/cons/default.cc: Likewise.
	* testsuite/ext/random/nakagami_distribution/cons/default.cc: Likewise.
	* testsuite/ext/random/normal_mv_distribution/cons/default.cc:
	Likewise.
	* testsuite/ext/random/pareto_distribution/cons/default.cc: Likewise.
	* testsuite/ext/random/rice_distribution/cons/default.cc: Likewise.
	* testsuite/ext/random/triangular_distribution/cons/default.cc:
	Likewise.
	* testsuite/ext/random/uniform_inside_sphere_distribution/cons/default.cc:
	Likewise.
	* testsuite/ext/random/uniform_on_sphere_distribution/cons/default.cc:
	Likewise.
	* testsuite/ext/random/von_mises_distribution/cons/default.cc:
	Likewise.

From-SVN: r261592

38 files changed, 217 insertions, 47 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 490dd24..738b7ac 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,95 @@
+2018-06-14  Jonathan Wakely  <jwakely@redhat.com>
+
+	P0935R0 Eradicating unnecessarily explicit default constructors
+	* include/bits/random.h (uniform_real_distribution::param_type)
+	(normal_distribution::param_type, lognormal_distribution::param_type)
+	(gamma_distribution::param_type, chi_squared_distribution::param_type)
+	(cauchy_distribution::param_type, fisher_f_distribution::param_type)
+	(student_t_distribution::param_type)
+	(bernoulli_distribution::param_type)
+	(binomial_distribution::param_type)
+	(geometric_distribution::param_type)
+	(negative_binomial_distribution::param_type)
+	(poisson_distribution::param_type)
+	(exponential_distribution::param_type)
+	(weibull_distribution::param_type)
+	(extreme_value_distribution::param_type): Add non-explicit default
+	constructors. Remove default argument for first parameter of explicit
+	constructors.
+	* include/bits/uniform_int_dist.h
+	(uniform_int_distribution::param_type): Likewise.
+	* include/ext/random
+	(beta_distribution::param_type, rice_distribution::param_type)
+	(nakagami_distribution::param_type, pareto_distribution::param_type)
+	(k_distribution::param_type, arcsine_distribution::param_type)
+	(hoyt_distribution::param_type, triangular_distribution::param_type)
+	(von_mises_distribution::param_type)
+	(hypergeometric_distribution::param_type)
+	(logistic_distribution::param_type)
+	(uniform_inside_sphere_distribution::param_type): Likewise.
+	(uniform_on_sphere_distribution::param_type): Make default constructor
+	non-explicit.
+	* testsuite/26_numerics/random/bernoulli_distribution/cons/default.cc:
+	Test param_type for non-explicit default constructor.
+	* testsuite/26_numerics/random/binomial_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/cauchy_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/chi_squared_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/discrete_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/exponential_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/extreme_value_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/fisher_f_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/gamma_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/geometric_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/lognormal_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/negative_binomial_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/normal_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/piecewise_constant_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/piecewise_linear_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/poisson_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/student_t_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/uniform_int_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/uniform_real_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/26_numerics/random/weibull_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/ext/random/arcsine_distribution/cons/default.cc: Likewise.
+	* testsuite/ext/random/beta_distribution/cons/default.cc: Likewise.
+	* testsuite/ext/random/hoyt_distribution/cons/default.cc: Likewise.
+	* testsuite/ext/random/hypergeometric_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/ext/random/k_distribution/cons/default.cc: Likewise.
+	* testsuite/ext/random/logistic_distribution/cons/default.cc: Likewise.
+	* testsuite/ext/random/nakagami_distribution/cons/default.cc: Likewise.
+	* testsuite/ext/random/normal_mv_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/ext/random/pareto_distribution/cons/default.cc: Likewise.
+	* testsuite/ext/random/rice_distribution/cons/default.cc: Likewise.
+	* testsuite/ext/random/triangular_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/ext/random/uniform_inside_sphere_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/ext/random/uniform_on_sphere_distribution/cons/default.cc:
+	Likewise.
+	* testsuite/ext/random/von_mises_distribution/cons/default.cc:
+	Likewise.
+
 2018-06-14  Daniel Trebbien <dtrebbien@gmail.com>
 	    Jonathan Wakely  <jwakely@redhat.com>
 
diff --git a/libstdc++-v3/include/bits/random.h b/libstdc++-v3/include/bits/random.h
index 252b14d..738c62f 100644
--- a/libstdc++-v3/include/bits/random.h
+++ b/libstdc++-v3/include/bits/random.h
@@ -1745,9 +1745,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef uniform_real_distribution<_RealType> distribution_type;
 
+	param_type() : param_type(0) { }
+
 	explicit
-	param_type(_RealType __a = _RealType(0),
-		   _RealType __b = _RealType(1))
+	param_type(_RealType __a, _RealType __b = _RealType(1))
 	: _M_a(__a), _M_b(__b)
 	{
 	  __glibcxx_assert(_M_a <= _M_b);
@@ -1974,9 +1975,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef normal_distribution<_RealType> distribution_type;
 
+	param_type() : param_type(0.0) { }
+
 	explicit
-	param_type(_RealType __mean = _RealType(0),
-		   _RealType __stddev = _RealType(1))
+	param_type(_RealType __mean, _RealType __stddev = _RealType(1))
 	: _M_mean(__mean), _M_stddev(__stddev)
 	{
 	  __glibcxx_assert(_M_stddev > _RealType(0));
@@ -2194,9 +2196,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef lognormal_distribution<_RealType> distribution_type;
 
+	param_type() : param_type(0.0) { }
+
 	explicit
-	param_type(_RealType __m = _RealType(0),
-		   _RealType __s = _RealType(1))
+	param_type(_RealType __m, _RealType __s = _RealType(1))
 	: _M_m(__m), _M_s(__s)
 	{ }
 
@@ -2405,9 +2408,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	typedef gamma_distribution<_RealType> distribution_type;
 	friend class gamma_distribution<_RealType>;
 
+	param_type() : param_type(1.0) { }
+
 	explicit
-	param_type(_RealType __alpha_val = _RealType(1),
-		   _RealType __beta_val = _RealType(1))
+	param_type(_RealType __alpha_val, _RealType __beta_val = _RealType(1))
 	: _M_alpha(__alpha_val), _M_beta(__beta_val)
 	{
 	  __glibcxx_assert(_M_alpha > _RealType(0));
@@ -2631,8 +2635,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef chi_squared_distribution<_RealType> distribution_type;
 
+	param_type() : param_type(1) { }
+
 	explicit
-	param_type(_RealType __n = _RealType(1))
+	param_type(_RealType __n)
 	: _M_n(__n)
 	{ }
 
@@ -2853,9 +2859,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef cauchy_distribution<_RealType> distribution_type;
 
+	param_type() : param_type(0) { }
+
 	explicit
-	param_type(_RealType __a = _RealType(0),
-		   _RealType __b = _RealType(1))
+	param_type(_RealType __a, _RealType __b = _RealType(1))
 	: _M_a(__a), _M_b(__b)
 	{ }
 
@@ -3060,9 +3067,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef fisher_f_distribution<_RealType> distribution_type;
 
+	param_type() : param_type(1) { }
+
 	explicit
-	param_type(_RealType __m = _RealType(1),
-		   _RealType __n = _RealType(1))
+	param_type(_RealType __m, _RealType __n = _RealType(1))
 	: _M_m(__m), _M_n(__n)
 	{ }
 
@@ -3291,8 +3299,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef student_t_distribution<_RealType> distribution_type;
 
+	param_type() : param_type(1) { }
+
 	explicit
-	param_type(_RealType __n = _RealType(1))
+	param_type(_RealType __n)
 	: _M_n(__n)
 	{ }
 
@@ -3513,8 +3523,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       typedef bernoulli_distribution distribution_type;
 
+      param_type() : param_type(0.5) { }
+
       explicit
-      param_type(double __p = 0.5)
+      param_type(double __p)
       : _M_p(__p)
       {
 	__glibcxx_assert((_M_p >= 0.0) && (_M_p <= 1.0));
@@ -3732,8 +3744,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	typedef binomial_distribution<_IntType> distribution_type;
 	friend class binomial_distribution<_IntType>;
 
+	param_type() : param_type(1) { }
+
 	explicit
-	param_type(_IntType __t = _IntType(1), double __p = 0.5)
+	param_type(_IntType __t, double __p = 0.5)
 	: _M_t(__t), _M_p(__p)
 	{
 	  __glibcxx_assert((_M_t >= _IntType(0))
@@ -3970,8 +3984,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	typedef geometric_distribution<_IntType> distribution_type;
 	friend class geometric_distribution<_IntType>;
 
+	param_type() : param_type(0.5) { }
+
 	explicit
-	param_type(double __p = 0.5)
+	param_type(double __p)
 	: _M_p(__p)
 	{
 	  __glibcxx_assert((_M_p > 0.0) && (_M_p < 1.0));
@@ -4177,8 +4193,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef negative_binomial_distribution<_IntType> distribution_type;
 
+	param_type() : param_type(1) { }
+
 	explicit
-	param_type(_IntType __k = 1, double __p = 0.5)
+	param_type(_IntType __k, double __p = 0.5)
 	: _M_k(__k), _M_p(__p)
 	{
 	  __glibcxx_assert((_M_k > 0) && (_M_p > 0.0) && (_M_p <= 1.0));
@@ -4407,8 +4425,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	typedef poisson_distribution<_IntType> distribution_type;
 	friend class poisson_distribution<_IntType>;
 
+	param_type() : param_type(1.0) { }
+
 	explicit
-	param_type(double __mean = 1.0)
+	param_type(double __mean)
 	: _M_mean(__mean)
 	{
 	  __glibcxx_assert(_M_mean > 0.0);
@@ -4630,8 +4650,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef exponential_distribution<_RealType> distribution_type;
 
+	param_type() : param_type(1.0) { }
+
 	explicit
-	param_type(_RealType __lambda = _RealType(1))
+	param_type(_RealType __lambda)
 	: _M_lambda(__lambda)
 	{
 	  __glibcxx_assert(_M_lambda > _RealType(0));
@@ -4843,9 +4865,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef weibull_distribution<_RealType> distribution_type;
 
+	param_type() : param_type(1.0) { }
+
 	explicit
-	param_type(_RealType __a = _RealType(1),
-		   _RealType __b = _RealType(1))
+	param_type(_RealType __a, _RealType __b = _RealType(1.0))
 	: _M_a(__a), _M_b(__b)
 	{ }
 
@@ -5052,9 +5075,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef extreme_value_distribution<_RealType> distribution_type;
 
+	param_type() : param_type(0.0) { }
+
 	explicit
-	param_type(_RealType __a = _RealType(0),
-		   _RealType __b = _RealType(1))
+	param_type(_RealType __a, _RealType __b = _RealType(1.0))
 	: _M_a(__a), _M_b(__b)
 	{ }
 
diff --git a/libstdc++-v3/include/bits/uniform_int_dist.h b/libstdc++-v3/include/bits/uniform_int_dist.h
index 3b6d504..f339f62 100644
--- a/libstdc++-v3/include/bits/uniform_int_dist.h
+++ b/libstdc++-v3/include/bits/uniform_int_dist.h
@@ -68,9 +68,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef uniform_int_distribution<_IntType> distribution_type;
 
+	param_type() : param_type(0) { }
+
 	explicit
-	param_type(_IntType __a = 0,
-		   _IntType __b = std::numeric_limits<_IntType>::max())
+	param_type(_IntType __a,
+		   _IntType __b = numeric_limits<_IntType>::max())
 	: _M_a(__a), _M_b(__b)
 	{
 	  __glibcxx_assert(_M_a <= _M_b);
@@ -108,7 +110,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        */
       explicit
       uniform_int_distribution(_IntType __a,
-			   _IntType __b = std::numeric_limits<_IntType>::max())
+			       _IntType __b = numeric_limits<_IntType>::max())
       : _M_param(__a, __b)
       { }
 
diff --git a/libstdc++-v3/include/ext/random b/libstdc++-v3/include/ext/random
index 3c714f5..7b2d1ea 100644
--- a/libstdc++-v3/include/ext/random
+++ b/libstdc++-v3/include/ext/random
@@ -424,9 +424,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	typedef beta_distribution<_RealType> distribution_type;
 	friend class beta_distribution<_RealType>;
 
+	param_type() : param_type(1) { }
+
 	explicit
-	param_type(_RealType __alpha_val = _RealType(1),
-		   _RealType __beta_val = _RealType(1))
+	param_type(_RealType __alpha_val, _RealType __beta_val = _RealType(1))
 	: _M_alpha(__alpha_val), _M_beta(__beta_val)
 	{
 	  __glibcxx_assert(_M_alpha > _RealType(0));
@@ -972,7 +973,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef rice_distribution<result_type> distribution_type;
 
-	param_type(result_type __nu_val = result_type(0),
+	param_type() : param_type(0) { }
+
+	param_type(result_type __nu_val,
 		   result_type __sigma_val = result_type(1))
 	: _M_nu(__nu_val), _M_sigma(__sigma_val)
 	{
@@ -1224,7 +1227,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef nakagami_distribution<result_type> distribution_type;
 
-	param_type(result_type __mu_val = result_type(1),
+	param_type() : param_type(1) { }
+
+	param_type(result_type __mu_val,
 		   result_type __omega_val = result_type(1))
 	: _M_mu(__mu_val), _M_omega(__omega_val)
 	{
@@ -1467,7 +1472,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef pareto_distribution<result_type> distribution_type;
 
-	param_type(result_type __alpha_val = result_type(1),
+	param_type() : param_type(1) { }
+
+	param_type(result_type __alpha_val,
 		   result_type __mu_val = result_type(1))
 	: _M_alpha(__alpha_val), _M_mu(__mu_val)
 	{
@@ -1712,7 +1719,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef k_distribution<result_type> distribution_type;
 
-	param_type(result_type __lambda_val = result_type(1),
+	param_type() : param_type(1) { }
+
+	param_type(result_type __lambda_val,
 		   result_type __mu_val = result_type(1),
 		   result_type __nu_val = result_type(1))
 	: _M_lambda(__lambda_val), _M_mu(__mu_val), _M_nu(__nu_val)
@@ -1964,8 +1973,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef arcsine_distribution<result_type> distribution_type;
 
-	param_type(result_type __a = result_type(0),
-		   result_type __b = result_type(1))
+	param_type() : param_type(0) { }
+
+	param_type(result_type __a, result_type __b = result_type(1))
 	: _M_a(__a), _M_b(__b)
 	{
 	  __glibcxx_assert(_M_a <= _M_b);
@@ -2210,8 +2220,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef hoyt_distribution<result_type> distribution_type;
 
-	param_type(result_type __q = result_type(0.5L),
-		   result_type __omega = result_type(1))
+	param_type() : param_type(0.5) { }
+
+	param_type(result_type __q, result_type __omega = result_type(1))
 	: _M_q(__q), _M_omega(__omega)
 	{
 	  __glibcxx_assert(_M_q > result_type(0));
@@ -2450,8 +2461,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	friend class triangular_distribution<_RealType>;
 
+	param_type() : param_type(0) { }
+
 	explicit
-	param_type(_RealType __a = _RealType(0),
+	param_type(_RealType __a,
 		   _RealType __b = _RealType(0.5),
 		   _RealType __c = _RealType(1))
 	: _M_a(__a), _M_b(__b), _M_c(__c)
@@ -2715,9 +2728,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	friend class von_mises_distribution<_RealType>;
 
+	param_type() : param_type(0) { }
+
 	explicit
-	param_type(_RealType __mu = _RealType(0),
-		   _RealType __kappa = _RealType(1))
+	param_type(_RealType __mu, _RealType __kappa = _RealType(1))
 	: _M_mu(__mu), _M_kappa(__kappa)
 	{
 	  const _RealType __pi = __gnu_cxx::__math_constants<_RealType>::__pi;
@@ -2958,8 +2972,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	typedef hypergeometric_distribution<_UIntType> distribution_type;
 	friend class hypergeometric_distribution<_UIntType>;
 
+	param_type() : param_type(10) { }
+
 	explicit
-	param_type(result_type __N = 10, result_type __K = 5,
+	param_type(result_type __N, result_type __K = 5,
 		   result_type __n = 1)
 	: _M_N{__N}, _M_K{__K}, _M_n{__n}
 	{
@@ -3224,8 +3240,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	typedef logistic_distribution<result_type> distribution_type;
 
-	param_type(result_type __a = result_type(0),
-		   result_type __b = result_type(1))
+	param_type() : param_type(0) { }
+
+	explicit
+	param_type(result_type __a, result_type __b = result_type(1))
 	: _M_a(__a), _M_b(__b)
 	{
 	  __glibcxx_assert(_M_b > result_type(0));
@@ -3436,9 +3454,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       /** Parameter type. */
       struct param_type
       {
-	explicit
-	param_type()
-	{ }
+	param_type() { }
 
 	friend bool
 	operator==(const param_type&, const param_type&)
@@ -3634,8 +3650,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  = uniform_inside_sphere_distribution<_Dimen, _RealType>;
 	friend class uniform_inside_sphere_distribution<_Dimen, _RealType>;
 
+	param_type() : param_type(1.0) { }
+
 	explicit
-	param_type(_RealType __radius = _RealType(1))
+	param_type(_RealType __radius)
 	: _M_radius(__radius)
 	{
 	  __glibcxx_assert(_M_radius > _RealType(0));
diff --git a/libstdc++-v3/testsuite/26_numerics/random/bernoulli_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/bernoulli_distribution/cons/default.cc
index 42096c0..2d5cb07 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/bernoulli_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/bernoulli_distribution/cons/default.cc
@@ -42,6 +42,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::bernoulli_distribution>();
+  test.operator()<std::bernoulli_distribution::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/26_numerics/random/binomial_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/binomial_distribution/cons/default.cc
index 6cf82f1..b5d616e 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/binomial_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/binomial_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::binomial_distribution<>>();
+  test.operator()<std::binomial_distribution<>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/26_numerics/random/cauchy_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/cauchy_distribution/cons/default.cc
index c1c71ce..5bcf183 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/cauchy_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/cauchy_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::cauchy_distribution<>>();
+  test.operator()<std::cauchy_distribution<>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/26_numerics/random/chi_squared_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/chi_squared_distribution/cons/default.cc
index 8ecf7c0..bdd397f 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/chi_squared_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/chi_squared_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::chi_squared_distribution<>>();
+  test.operator()<std::chi_squared_distribution<>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/26_numerics/random/discrete_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/discrete_distribution/cons/default.cc
index 0e837ed..909986c 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/discrete_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/discrete_distribution/cons/default.cc
@@ -42,6 +42,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::discrete_distribution<>>();
+  test.operator()<std::discrete_distribution<>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/26_numerics/random/exponential_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/exponential_distribution/cons/default.cc
index 7285bd3..0edd542 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/exponential_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/exponential_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::exponential_distribution<>>();
+  test.operator()<std::exponential_distribution<>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/26_numerics/random/extreme_value_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/extreme_value_distribution/cons/default.cc
index f9187fc..124ed8d 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/extreme_value_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/extreme_value_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::extreme_value_distribution<>>();
+  test.operator()<std::extreme_value_distribution<>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/26_numerics/random/fisher_f_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/fisher_f_distribution/cons/default.cc
index 3032ade..44324ea 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/fisher_f_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/fisher_f_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::fisher_f_distribution<>>();
+  test.operator()<std::fisher_f_distribution<>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/26_numerics/random/gamma_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/gamma_distribution/cons/default.cc
index 84d2bb7..50f5933 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/gamma_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/gamma_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::gamma_distribution<>>();
+  test.operator()<std::gamma_distribution<>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/26_numerics/random/geometric_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/geometric_distribution/cons/default.cc
index d16a2f0..a6f1244 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/geometric_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/geometric_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::geometric_distribution<>>();
+  test.operator()<std::geometric_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/26_numerics/random/lognormal_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/lognormal_distribution/cons/default.cc
index 5512905..3e6cd14 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/lognormal_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/lognormal_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::lognormal_distribution<>>();
+  test.operator()<std::lognormal_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/26_numerics/random/negative_binomial_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/negative_binomial_distribution/cons/default.cc
index 32847df..8f74de9 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/negative_binomial_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/negative_binomial_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::negative_binomial_distribution<>>();
+  test.operator()<std::negative_binomial_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/26_numerics/random/normal_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/normal_distribution/cons/default.cc
index dd3e0d2..0c2b84e 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/normal_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/normal_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::normal_distribution<>>();
+  test.operator()<std::normal_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/default.cc
index 84507b4..a90f87b 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/piecewise_constant_distribution/cons/default.cc
@@ -46,6 +46,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::piecewise_constant_distribution<>>();
+  test.operator()<std::piecewise_constant_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/default.cc
index e439adf..7db4e3f 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/piecewise_linear_distribution/cons/default.cc
@@ -47,6 +47,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::piecewise_linear_distribution<>>();
+  test.operator()<std::piecewise_linear_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/26_numerics/random/poisson_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/poisson_distribution/cons/default.cc
index c357581..82b6a1c 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/poisson_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/poisson_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::poisson_distribution<>>();
+  test.operator()<std::poisson_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/26_numerics/random/student_t_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/student_t_distribution/cons/default.cc
index 06c7dee..9bdba65 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/student_t_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/student_t_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::student_t_distribution<>>();
+  test.operator()<std::student_t_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/26_numerics/random/uniform_int_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/uniform_int_distribution/cons/default.cc
index 8774e66..0774a14 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/uniform_int_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/uniform_int_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::uniform_int_distribution<>>();
+  test.operator()<std::uniform_int_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/cons/default.cc
index 6a47a4d..85a697f7 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::uniform_real_distribution<>>();
+  test.operator()<std::uniform_real_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/26_numerics/random/weibull_distribution/cons/default.cc b/libstdc++-v3/testsuite/26_numerics/random/weibull_distribution/cons/default.cc
index 96db58f..4bb2fb7 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/weibull_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/weibull_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<std::weibull_distribution<>>();
+  test.operator()<std::weibull_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/arcsine_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/arcsine_distribution/cons/default.cc
index 76b5166..fc06991 100644
--- a/libstdc++-v3/testsuite/ext/random/arcsine_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/arcsine_distribution/cons/default.cc
@@ -39,6 +39,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::arcsine_distribution<>>();
+  test.operator()<__gnu_cxx::arcsine_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/beta_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/beta_distribution/cons/default.cc
index 9675a55..3514796 100644
--- a/libstdc++-v3/testsuite/ext/random/beta_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/beta_distribution/cons/default.cc
@@ -40,6 +40,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::beta_distribution<>>();
+  test.operator()<__gnu_cxx::beta_distribution<>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/ext/random/hoyt_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/hoyt_distribution/cons/default.cc
index 5302234..1e11a90 100644
--- a/libstdc++-v3/testsuite/ext/random/hoyt_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/hoyt_distribution/cons/default.cc
@@ -40,6 +40,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::hoyt_distribution<>>();
+  test.operator()<__gnu_cxx::hoyt_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/hypergeometric_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/hypergeometric_distribution/cons/default.cc
index d4078d4..06d9432 100644
--- a/libstdc++-v3/testsuite/ext/random/hypergeometric_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/hypergeometric_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::hypergeometric_distribution<>>();
+  test.operator()<__gnu_cxx::hypergeometric_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/k_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/k_distribution/cons/default.cc
index cc11ccb..f6677c7 100644
--- a/libstdc++-v3/testsuite/ext/random/k_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/k_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::k_distribution<>>();
+  test.operator()<__gnu_cxx::k_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/logistic_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/logistic_distribution/cons/default.cc
index 3d7db75..d66d76a 100644
--- a/libstdc++-v3/testsuite/ext/random/logistic_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/logistic_distribution/cons/default.cc
@@ -44,6 +44,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::logistic_distribution<>>();
+  test.operator()<__gnu_cxx::logistic_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/nakagami_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/nakagami_distribution/cons/default.cc
index ea473f2..8c41597 100644
--- a/libstdc++-v3/testsuite/ext/random/nakagami_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/nakagami_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::nakagami_distribution<>>();
+  test.operator()<__gnu_cxx::nakagami_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/normal_mv_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/normal_mv_distribution/cons/default.cc
index c209a8d..828c298 100644
--- a/libstdc++-v3/testsuite/ext/random/normal_mv_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/normal_mv_distribution/cons/default.cc
@@ -46,6 +46,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::normal_mv_distribution<2>>();
+  test.operator()<__gnu_cxx::normal_mv_distribution<2>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/ext/random/pareto_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/pareto_distribution/cons/default.cc
index 368d7da..440eefa 100644
--- a/libstdc++-v3/testsuite/ext/random/pareto_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/pareto_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::pareto_distribution<>>();
+  test.operator()<__gnu_cxx::pareto_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/rice_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/rice_distribution/cons/default.cc
index 1483f87..014bcd5 100644
--- a/libstdc++-v3/testsuite/ext/random/rice_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/rice_distribution/cons/default.cc
@@ -43,6 +43,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::rice_distribution<>>();
+  test.operator()<__gnu_cxx::rice_distribution<>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/triangular_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/triangular_distribution/cons/default.cc
index c7c6aba..1726a82 100644
--- a/libstdc++-v3/testsuite/ext/random/triangular_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/triangular_distribution/cons/default.cc
@@ -41,6 +41,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::triangular_distribution<>>();
+  test.operator()<__gnu_cxx::triangular_distribution<>::param_type>();
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/ext/random/uniform_inside_sphere_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/uniform_inside_sphere_distribution/cons/default.cc
index e15a12d..6b2f579 100644
--- a/libstdc++-v3/testsuite/ext/random/uniform_inside_sphere_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/uniform_inside_sphere_distribution/cons/default.cc
@@ -41,6 +41,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::uniform_inside_sphere_distribution<2>>();
+  test.operator()<__gnu_cxx::uniform_inside_sphere_distribution<2>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/uniform_on_sphere_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/uniform_on_sphere_distribution/cons/default.cc
index 8aa81b3..95e1783 100644
--- a/libstdc++-v3/testsuite/ext/random/uniform_on_sphere_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/uniform_on_sphere_distribution/cons/default.cc
@@ -40,6 +40,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::uniform_on_sphere_distribution<2>>();
+  test.operator()<__gnu_cxx::uniform_on_sphere_distribution<2>::param_type>();
 }
 
 int
diff --git a/libstdc++-v3/testsuite/ext/random/von_mises_distribution/cons/default.cc b/libstdc++-v3/testsuite/ext/random/von_mises_distribution/cons/default.cc
index 1a4784d..7e17f4d 100644
--- a/libstdc++-v3/testsuite/ext/random/von_mises_distribution/cons/default.cc
+++ b/libstdc++-v3/testsuite/ext/random/von_mises_distribution/cons/default.cc
@@ -40,6 +40,7 @@ test02()
 {
   __gnu_test::implicitly_default_constructible test;
   test.operator()<__gnu_cxx::von_mises_distribution<>>();
+  test.operator()<__gnu_cxx::von_mises_distribution<>::param_type>();
 }
 
 int main()