From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 11 Aug 2021 21:11:19 +0000 (+0100)
Subject: libstdc++: Fix test that fails randomly [PR101866]
X-Git-Tag: basepoints/gcc-13~5447
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=93f1dbc7cdcc4b31ea4061efb4c2acf2d4f81eb8;p=thirdparty%2Fgcc.git

libstdc++: Fix test that fails randomly [PR101866]

This test assumes that the same sequence of three values cannot occur,
which is incorect. It's unlikely, but not impossible.

Perform the check in a loop, so that in the unlikely event of an
identical sequence, we retry. If the library code is buggy it will keep
producing the same sequence and the test will time out. If the code is
working correctly then we will usually break out of the loop after one
iteration, or very rarely after two or three.

libstdc++-v3/ChangeLog:

	PR libstdc++/101866
	* testsuite/experimental/random/randint.cc: Loop and retry if
	reseed() produces the same sequence.
---

diff --git a/libstdc++-v3/testsuite/experimental/random/randint.cc b/libstdc++-v3/testsuite/experimental/random/randint.cc
index d6225eba1dfb..e05151e5ea09 100644
--- a/libstdc++-v3/testsuite/experimental/random/randint.cc
+++ b/libstdc++-v3/testsuite/experimental/random/randint.cc
@@ -34,7 +34,7 @@ test01()
   }
 
   std::experimental::reseed(99u);
-  const long n1[] = {
+  const int n1[] = {
     std::experimental::randint(0, 100),
     std::experimental::randint(0, 100),
     std::experimental::randint(0, 100),
@@ -42,7 +42,7 @@ test01()
     std::experimental::randint(0, 100)
   };
   std::experimental::reseed(99u);
-  const long n2[] = {
+  const int n2[] = {
     std::experimental::randint(0, 100),
     std::experimental::randint(0, 100),
     std::experimental::randint(0, 100),
@@ -52,13 +52,13 @@ test01()
   for (int i = 0; i < 5; ++i)
     VERIFY( n1[i] == n2[i] );
 
-  std::experimental::reseed();
-  const long n3[] = {
-    std::experimental::randint(0, 100),
-    std::experimental::randint(0, 100),
-    std::experimental::randint(0, 100)
-  };
-  VERIFY( !(n3[0] == n1[0] && n3[1] == n1[1] && n3[2] == n1[2]) );
+  do
+  {
+    std::experimental::reseed();
+  }
+  while (std::experimental::randint(0, 100) == n1[0]
+      && std::experimental::randint(0, 100) == n1[1]
+      && std::experimental::randint(0, 100) == n1[2]);
 }
 
 void