On 32-bit x86 the default -fexcess-precision=fast setting used by
-std=gnu++20 results in unpredictable rounding which alters the number
of times that std::generate_canonical produces exactly 1.0f, which
means that the URBG is invoked a different number of times.
To ensure that the behaviour is consistent and the expected number of
calls happens, use -fexcess-precision=standard.
libstdc++-v3/ChangeLog:
*
testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc:
Add -fexcess-precision=standard to options.
*
testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc:
Likewise.
---
Tested x86_64-linux
Also checked -m32 and -D_GLIBCXX_USE_OLD_GENERATE_CANONICAL
.../random/uniform_real_distribution/operators/64351.cc | 1 +
.../random/uniform_real_distribution/operators/gencanon.cc | 1 +
2 files changed, 2 insertions(+)
diff --git
a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc
b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc
index 3031984df15a..f457bc6e0fc9 100644
---
a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc
+++
b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc
@@ -17,6 +17,7 @@
// { dg-do run { target { c++11 && { ! simulator } } } }
// { dg-require-cstdint "" }
+// { dg-additional-options -fexcess-precision=standard }
#include <random>
#include <testsuite_hooks.h>
diff --git
a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc
b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc
index 87ad206a78a4..69a061071da0 100644
---
a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc
+++
b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc
@@ -1,5 +1,6 @@
// { dg-do run { target { c++11 && { ! simulator } } } }
// { dg-skip-if "requires new impl" { *-*-* } {
-D_GLIBCXX_USE_OLD_GENERATE_CANONICAL -D_GLIBCXX_USE_OLD_GENERATE_CANONICAL=1 }
}
+// { dg-additional-options -fexcess-precision=standard }
#include <random>
#include <limits>
--
2.52.0
