On Tue, Dec 16, 2025 at 02:52:27PM -0500, Nathan Myers wrote:
> PR libstdc++/119739
> * include/bits/random.tcc: Add generate_canonical impl for C++26.
> *
> testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc:
> Adapt test for both pre- and post- C++26.
> *
> testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc:
> Test for float and double from 32-bit RNG, including 1.0 do-over.
This breaks some tests.
On x86_64-linux
FAIL: 17_intro/headers/c++1998/all_pedantic_errors.cc -std=gnu++17 (test for
excess errors)
Excess errors:
/home/jakub/src/gcc/obj20/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/random.tcc:3681:
error: ISO C++ does not support '__int128' for 'type name' [-Wpedantic]
/home/jakub/src/gcc/obj20/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/random.tcc:3698:
error: ISO C++ does not support '__int128' for 'type name' [-Wpedantic]
for which I'm attaching patch below,
FAIL: std/ranges/adaptors/93978.cc -std=gnu++20 (test for excess errors)
Excess errors:
/home/jakub/src/gcc/obj20/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/random.tcc:3664:
warning: typedef 'using _Rng = decltype (_Urbg::max())' locally defined but
not used [-Wunused-local-typedefs]
FAIL: std/ranges/adaptors/93978.cc -std=gnu++26 (test for excess errors)
Excess errors:
/home/jakub/src/gcc/obj20/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/random.tcc:3664:
warning: typedef 'using _Rng = decltype (_Urbg::max())' locally defined but
not used [-Wunused-local-typedefs]
where that
using _Rng = decltype(_Urbg::max());
indeed looks unused and it is unclear if you want to use
it somewhere or remove,
FAIL: 26_numerics/random/pr60037-neg.cc -std=gnu++17 (test for errors, line
3480)
FAIL: 26_numerics/random/pr60037-neg.cc -std=gnu++17 (test for excess errors)
Excess errors:
/home/jakub/src/gcc/obj20/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/random.tcc:3653:
error: static assertion failed: template argument must be floating point
and on i686-linux tons of further FAILs like:
FAIL: 26_numerics/random/fisher_f_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
Excess errors:
/home/jakub/src/gcc/obj21/i686-pc-linux-gnu/libstdc++-v3/include/bits/random.tcc:3700:
error: static assertion failed: irregular RNG with float precision >32
requires __int128 support
/home/jakub/src/gcc/obj21/i686-pc-linux-gnu/libstdc++-v3/include/bits/random.tcc:3705:
warning: no return statement in function returning non-void [-Wreturn-type]
UNRESOLVED: 26_numerics/random/fisher_f_distribution/operators/serialize.cc
-std=gnu++17 compilation failed to produce executable
I think it is all of
FAIL: 20_util/is_function/91371.cc -std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/bernoulli_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/binomial_distribution/114359.cc -std=gnu++17 (test
for excess errors)
FAIL: 26_numerics/random/binomial_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/cauchy_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/chi_squared_distribution/83833.cc -std=gnu++17 (test
for excess errors)
FAIL: 26_numerics/random/chi_squared_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/discrete_distribution/operators/call-default.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/discrete_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/exponential_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/extreme_value_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/fisher_f_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/gamma_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/geometric_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/lognormal_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/negative_binomial_distribution/operators/58302.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/negative_binomial_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/normal_distribution/operators/equal.cc -std=gnu++17
(test for excess errors)
FAIL: 26_numerics/random/normal_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL:
26_numerics/random/piecewise_constant_distribution/operators/call-default.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/piecewise_constant_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL:
26_numerics/random/piecewise_linear_distribution/operators/call-default.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/piecewise_linear_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/poisson_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/pr60037-neg.cc -std=gnu++17 (test for errors, line
3480)
FAIL: 26_numerics/random/pr60037-neg.cc -std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/student_t_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/uniform_real_distribution/operators/64351.cc
-std=gnu++17 execution test
FAIL: 26_numerics/random/uniform_real_distribution/operators/gencanon.cc
-std=gnu++17 execution test
FAIL: 26_numerics/random/uniform_real_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: 26_numerics/random/weibull_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: ext/random/arcsine_distribution/operators/serialize.cc -std=gnu++17
(test for excess errors)
FAIL: ext/random/beta_distribution/operators/serialize.cc -std=gnu++17 (test
for excess errors)
FAIL: ext/random/hoyt_distribution/operators/serialize.cc -std=gnu++17 (test
for excess errors)
FAIL: ext/random/hypergeometric_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: ext/random/k_distribution/operators/serialize.cc -std=gnu++17 (test for
excess errors)
FAIL: ext/random/logistic_distribution/operators/serialize.cc -std=gnu++17
(test for excess errors)
FAIL: ext/random/nakagami_distribution/operators/serialize.cc -std=gnu++17
(test for excess errors)
FAIL: ext/random/normal_mv_distribution/operators/serialize.cc -std=gnu++17
(test for excess errors)
FAIL: ext/random/pareto_distribution/operators/serialize.cc -std=gnu++17 (test
for excess errors)
FAIL: ext/random/rice_distribution/operators/serialize.cc -std=gnu++17 (test
for excess errors)
FAIL: ext/random/triangular_distribution/operators/serialize.cc -std=gnu++17
(test for excess errors)
FAIL: ext/random/uniform_inside_sphere_distribution/operators/generate.cc
-std=gnu++17 (test for excess errors)
FAIL: ext/random/uniform_inside_sphere_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: ext/random/uniform_on_sphere_distribution/operators/generate.cc
-std=gnu++17 (test for excess errors)
FAIL: ext/random/uniform_on_sphere_distribution/operators/serialize.cc
-std=gnu++17 (test for excess errors)
FAIL: ext/random/von_mises_distribution/operators/serialize.cc -std=gnu++17
(test for excess errors)
Because we don't have unsigned _BitInt(128) in C++ right now, I'm afraid you
want some unsigned __int128 like class for #ifndef __SIZEOF_INT128__ which
will handle all the operations you need on a pair of unsigned long long.
Note, some time ago I was working on an int128 and uint128 for libgcobol,
https://gcc.gnu.org/bugzilla/attachment.cgi?id=61011 is the latest patch
(part of https://gcc.gnu.org/PR119595), it probably has far more than
you actually need and not the libstdc++-v3 formatting.
Anyway, here is just the quick __extension__ patch to fix up
all_pedantic_errors.cc.
Ok for trunk?
2025-12-17 Jakub Jelinek <[email protected]>
* include/bits/random.tcc (std::generate_canonical): Use
__extension__ before __generate_canonical_{pow2,any} calls with
unsigned __int128 template arguments.
--- libstdc++-v3/include/bits/random.tcc.jj 2025-12-16 22:26:28.485419458
+0100
+++ libstdc++-v3/include/bits/random.tcc 2025-12-17 07:25:12.633790536
+0100
@@ -3677,7 +3677,7 @@ namespace __detail
{
#if defined(__SIZEOF_INT128__)
// Accommodate double double or float128.
- return __generate_canonical_pow2<
+ return __extension__ __generate_canonical_pow2<
_RealT, unsigned __int128, __d>(__urng);
#else
static_assert(false,
@@ -3694,7 +3694,7 @@ namespace __detail
#if defined(__SIZEOF_INT128__)
static_assert(__d <= 64,
"irregular RNG with float precision >64 is not supported");
- return __generate_canonical_any<
+ return __extension__ __generate_canonical_any<
_RealT, unsigned __int128, __d>(__urng);
#else
static_assert(false, "irregular RNG with float precision"
Jakub
