From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 17 Dec 2025 19:39:39 +0000 (+0000)
Subject: libstdc++: Use -fexcess-precision=standard for std::generate_canonical tests
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a9eb2f24b01bea3193bdb77cc2aa13d6fbd0f754;p=thirdparty%2Fgcc.git

libstdc++: Use -fexcess-precision=standard for std::generate_canonical tests

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.

Reviewed-by: Jakub Jelinek <jakub@redhat.com>
---

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 3031984df15..f457bc6e0fc 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 87ad206a78a..69a061071da 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>