From: Jonathan Wakely <jwakely@redhat.com>
Date: Mon, 17 Oct 2016 17:03:09 +0000 (+0100)
Subject: Backport fixes to std::experimental::sample
X-Git-Tag: releases/gcc-5.5.0~764
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d73e8794f69c28329738adc7c8c8e1172fdabdf2;p=thirdparty%2Fgcc.git

Backport fixes to std::experimental::sample

	PR libstdc++/77994
	* include/experimental/algorithm (experimental::sample): Convert size
	argument to iterator difference type. Fix invalid use of input
	iterator. Defend against overloaded comma operator.

From-SVN: r241263
---

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 4cc7444dfec0..895192159816 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,10 @@
+2016-10-17  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/77994
+	* include/experimental/algorithm (experimental::sample): Convert size
+	argument to iterator difference type. Fix invalid use of input
+	iterator. Defend against overloaded comma operator.
+
 2016-10-05  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR libstdc++/70564
diff --git a/libstdc++-v3/include/experimental/algorithm b/libstdc++-v3/include/experimental/algorithm
index ce0a1491434c..11498fa8efcd 100644
--- a/libstdc++-v3/include/experimental/algorithm
+++ b/libstdc++-v3/include/experimental/algorithm
@@ -68,9 +68,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       __distrib_type __d{};
       _Size __sample_sz = 0;
       while (__first != __last && __sample_sz != __n)
-	__out[__sample_sz++] = *__first++;
+	{
+	  __out[__sample_sz++] = *__first;
+	  ++__first;
+	}
       for (auto __pop_sz = __sample_sz; __first != __last;
-	  ++__first, ++__pop_sz)
+	  ++__first, (void)++__pop_sz)
 	{
 	  const auto __k = __d(__g, __param_type{0, __pop_sz});
 	  if (__k < __n)
@@ -123,9 +126,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       static_assert(is_integral<_Distance>::value,
 		    "sample size must be an integer type");
 
+      typename iterator_traits<_PopulationIterator>::difference_type __d = __n;
       return std::experimental::__sample(
 	  __first, __last, __pop_cat{}, __out, __samp_cat{},
-	  __n, std::forward<_UniformRandomNumberGenerator>(__g));
+	  __d, std::forward<_UniformRandomNumberGenerator>(__g));
     }
 
 _GLIBCXX_END_NAMESPACE_VERSION
diff --git a/libstdc++-v3/testsuite/experimental/algorithm/sample.cc b/libstdc++-v3/testsuite/experimental/algorithm/sample.cc
index bfff9371d7f3..8bdd5f0a1170 100644
--- a/libstdc++-v3/testsuite/experimental/algorithm/sample.cc
+++ b/libstdc++-v3/testsuite/experimental/algorithm/sample.cc
@@ -22,6 +22,7 @@
 #include <sstream>
 #include <forward_list>
 #include <vector>
+#include <random>
 #include <testsuite_hooks.h>
 
 std::mt19937 rng;