From 0953497a81f1e320989b9f2aaa7f56747eddd4a0 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Fri, 10 Nov 2023 12:21:52 +0000
Subject: [PATCH] libstdc++: Add static_assert to std::integer_sequence
[PR112473]
C++20 allows class types as non-type template parameters, but
std::integer_sequence explicitly disallows them. Enforce that.
libstdc++-v3/ChangeLog:
PR libstdc++/112473
* include/bits/utility.h (integer_sequence): Add static_assert.
* testsuite/20_util/integer_sequence/112473.cc: New test.
---
libstdc++-v3/include/bits/utility.h | 3 +++
libstdc++-v3/testsuite/20_util/integer_sequence/112473.cc | 8 ++++++++
2 files changed, 11 insertions(+)
create mode 100644 libstdc++-v3/testsuite/20_util/integer_sequence/112473.cc
diff --git a/libstdc++-v3/include/bits/utility.h b/libstdc++-v3/include/bits/utility.h
index 8766dfbc15f1..ebcf5ba36b28 100644
--- a/libstdc++-v3/include/bits/utility.h
+++ b/libstdc++-v3/include/bits/utility.h
@@ -166,6 +166,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp, _Tp... _Idx>
struct integer_sequence
{
+#if __cplusplus >= 202002L
+ static_assert(is_integral_v<_Tp>);
+#endif
typedef _Tp value_type;
static constexpr size_t size() noexcept { return sizeof...(_Idx); }
};
diff --git a/libstdc++-v3/testsuite/20_util/integer_sequence/112473.cc b/libstdc++-v3/testsuite/20_util/integer_sequence/112473.cc
new file mode 100644
index 000000000000..14abfbc8149d
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/integer_sequence/112473.cc
@@ -0,0 +1,8 @@
+// { dg-do compile { target c++20 } }
+
+// PR libstdc++/112473 - integer_sequence accepts non-integer types
+
+#include <utility>
+
+std::integer_sequence<std::pair<int, int>, std::pair<int, int>{0, 0}> ic;
+// { dg-error "static assertion failed" "" { target *-*-* } 0 }
--
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