libstdc++: Add missing 'constexpr' to std::tuple [PR102270]

This backport to gcc-10 also includes r12-3637.

Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:

	PR libstdc++/102270
	* include/std/tuple (_Head_base, _Tuple_impl): Add
	_GLIBCXX20_CONSTEXPR to allocator-extended constructors.
	(tuple<>::swap(tuple&)): Add _GLIBCXX20_CONSTEXPR.
	* testsuite/20_util/tuple/cons/102270.cc: New test.
	* testsuite/util/testsuite_allocator.h (SimpleAllocator): Add
	constexpr to constructor so it can be used for C++20 tests.

diff --git a/libstdc++-v3/include/std/tuple b/libstdc++-v3/include/std/tuple
index 991215321014d544dff31b7c8d04fcf614bf1aed..fac6d4d656be6c7f4dcb2a580254c32049a8da13 100644 (file)
--- a/libstdc++-v3/include/std/tuple
+++ b/libstdc++-v3/include/std/tuple
@@ -90,26 +90,32 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
         constexpr _Head_base(_UHead&& __h)
        : _Head(std::forward<_UHead>(__h)) { }
 
+      _GLIBCXX20_CONSTEXPR
       _Head_base(allocator_arg_t, __uses_alloc0)
       : _Head() { }
 
       template<typename _Alloc>
+       _GLIBCXX20_CONSTEXPR
        _Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
        : _Head(allocator_arg, *__a._M_a) { }
 
       template<typename _Alloc>
+       _GLIBCXX20_CONSTEXPR
        _Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
        : _Head(*__a._M_a) { }
 
       template<typename _UHead>
+       _GLIBCXX20_CONSTEXPR
        _Head_base(__uses_alloc0, _UHead&& __uhead)
        : _Head(std::forward<_UHead>(__uhead)) { }
 
       template<typename _Alloc, typename _UHead>
+       _GLIBCXX20_CONSTEXPR
        _Head_base(__uses_alloc1<_Alloc> __a, _UHead&& __uhead)
        : _Head(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead)) { }
 
       template<typename _Alloc, typename _UHead>
+       _GLIBCXX20_CONSTEXPR
        _Head_base(__uses_alloc2<_Alloc> __a, _UHead&& __uhead)
        : _Head(std::forward<_UHead>(__uhead), *__a._M_a) { }
 
@@ -141,10 +147,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       : _M_head_impl() { }
 
       template<typename _Alloc>
+       _GLIBCXX20_CONSTEXPR
        _Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
        : _M_head_impl(allocator_arg, *__a._M_a) { }
 
       template<typename _Alloc>
+       _GLIBCXX20_CONSTEXPR
        _Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
        : _M_head_impl(*__a._M_a) { }
 
@@ -154,11 +162,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        : _M_head_impl(std::forward<_UHead>(__uhead)) { }
 
       template<typename _Alloc, typename _UHead>
+       _GLIBCXX20_CONSTEXPR
        _Head_base(__uses_alloc1<_Alloc> __a, _UHead&& __uhead)
        : _M_head_impl(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead))
        { }
 
       template<typename _Alloc, typename _UHead>
+       _GLIBCXX20_CONSTEXPR
        _Head_base(__uses_alloc2<_Alloc> __a, _UHead&& __uhead)
        : _M_head_impl(std::forward<_UHead>(__uhead), *__a._M_a) { }
 
@@ -255,6 +265,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
           _Base(__tag, __use_alloc<_Head>(__a)) { }
 
       template<typename _Alloc>
+       _GLIBCXX20_CONSTEXPR
        _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
                    const _Head& __head, const _Tail&... __tail)
        : _Inherited(__tag, __a, __tail...),
@@ -389,6 +400,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        : _Base(__tag, __use_alloc<_Head>(__a)) { }
 
       template<typename _Alloc>
+       _GLIBCXX20_CONSTEXPR
        _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
                    const _Head& __head)
        : _Base(__use_alloc<_Head, _Alloc, _Head>(__a), __head) { }
@@ -872,6 +884,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     class tuple<>
     {
     public:
+      _GLIBCXX20_CONSTEXPR
       void swap(tuple&) noexcept { /* no-op */ }
       // We need the default since we're going to define no-op
       // allocator constructors.

diff --git a/libstdc++-v3/testsuite/20_util/tuple/cons/102270.cc b/libstdc++-v3/testsuite/20_util/tuple/cons/102270.cc
new file mode 100644 (file)
index 0000000..5500cac
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/tuple/cons/102270.cc
@@ -0,0 +1,64 @@
+// { dg-options "-std=gnu++20" }
+// { dg-do compile { target c++20 } }
+
+#include <tuple>
+
+// PR libstdc++/102270 - std::tuple<>::swap missing constexpr specifier
+
+constexpr bool swap_empty_tuple()
+{
+  std::tuple<> t, u;
+  t.swap(u);
+  return true;
+}
+static_assert( swap_empty_tuple() );
+
+#include <testsuite_allocator.h>
+
+constexpr bool construct_using_allocator()
+{
+  using Alloc = __gnu_test::SimpleAllocator<int>;
+
+  Alloc a;
+  const int i = 0;
+
+  struct X0a {
+    using allocator_type = Alloc;
+    /* not constexpr */ X0a() { }
+    constexpr X0a(allocator_type) { }
+  };
+  std::tuple<X0a> t0a(std::allocator_arg, a);
+  std::tuple<X0a, X0a> t00a(std::allocator_arg, a);
+
+  struct X0b {
+    using allocator_type = Alloc;
+    /* not constexpr */ X0b() { }
+    constexpr X0b(std::allocator_arg_t, allocator_type) { }
+  };
+  std::tuple<X0b> t0b(std::allocator_arg, a);
+  std::tuple<X0b, X0b> t00b(std::allocator_arg, a);
+
+  struct X1a {
+    using allocator_type = Alloc;
+    /* not constexpr */ X1a(int) { }
+    constexpr X1a(int, allocator_type) { }
+  };
+  std::tuple<X1a> t1a(std::allocator_arg, a, 1);
+  std::tuple<X1a, X1a> t11a(std::allocator_arg, a, 1, i);
+
+  struct X1b {
+    using allocator_type = Alloc;
+    /* not constexpr */ X1b(int) { }
+    constexpr X1b(std::allocator_arg_t, allocator_type, int) { }
+  };
+  std::tuple<X1b> t1b(std::allocator_arg, a, 1);
+  std::tuple<X1b, X1b> t11b(std::allocator_arg, a, 1, i);
+
+  std::tuple<X1a, X1a, X1b, X1b> t1a1b(std::allocator_arg, a, 1, i, 1, i);
+
+  const int c = 0;
+  std::tuple<int, int> tii(std::allocator_arg, a, c, c);
+
+  return true;
+}
+static_assert( construct_using_allocator() );

diff --git a/libstdc++-v3/testsuite/util/testsuite_allocator.h b/libstdc++-v3/testsuite/util/testsuite_allocator.h
index e52ef7884679a58092f2fefd329bb51469f31f51..dacb4daf6b0913954166f9c1905494386dcbe673 100644 (file)
--- a/libstdc++-v3/testsuite/util/testsuite_allocator.h
+++ b/libstdc++-v3/testsuite/util/testsuite_allocator.h
@@ -512,7 +512,7 @@ namespace __gnu_test
     {
       typedef Tp value_type;
 
-      SimpleAllocator() noexcept { }
+      constexpr SimpleAllocator() noexcept { }
 
       template <class T>
         SimpleAllocator(const SimpleAllocator<T>&) { }