libstdc++: Add testcase for std::make_integer_sequence bug [PR111357]

The compiler bug has been fixed on trunk, but this adds a regression test
for the library component.

libstdc++-v3/ChangeLog:

	PR c++/111357
	* testsuite/20_util/integer_sequence/pr111357.cc: New test.

diff --git a/libstdc++-v3/testsuite/20_util/integer_sequence/pr111357.cc b/libstdc++-v3/testsuite/20_util/integer_sequence/pr111357.cc
new file mode 100644 (file)
index 0000000..1ad06b7
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/integer_sequence/pr111357.cc
@@ -0,0 +1,34 @@
+// { dg-do compile { target c++14 } }
+
+// PR c++/111357 - __integer_pack fails to work with values of dependent type
+// convertible to integers in noexcept context
+
+#include <utility>
+
+using std::integer_sequence;
+using std::make_integer_sequence;
+
+template<int... V>
+void g(integer_sequence<int,V...>)
+{}
+
+template<typename ...T>
+struct c1
+{
+  static constexpr int value = 1;
+  constexpr operator int() { return value; }
+};
+
+template<typename T>
+struct R
+{
+  using S = make_integer_sequence<int,c1<T>{}>;
+
+  R() noexcept(noexcept(g(S()))) // { dg-bogus "argument to .__integer_pack." }
+  {}
+};
+
+int main()
+{
+  R<int>();
+}