libstdc++: static_assert that static sized range size is less than inplace_vector...

Resolves LWG 4396. Improve inplace_vector(from_range_t, R&& rg)

The test case illustrates that views applied to span<T, N> are still
statically sized, but once applied to array<T, N> are not. This is
caused by the fact that ref_view stores a pointer to array, and
dereference of unknown pointers does not produce reference to unknown,
and simply yield non-constant expressions (unknown pointer is not
equivalent to pointer to unknown, as it may be null).

libstdc++-v3/ChangeLog:

	* include/std/inplace_vector (inplace_vector(std::from_range, __Rg&&)):
	Add static_asserts checking range size.
	* testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc:
	New test.
	* testsuite/23_containers/inplace_vector/cons/from_range_neg.cc:
	New test.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Reviewed-by: Patrick Palka <ppalka@redhat.com>
Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com>

diff --git a/libstdc++-v3/include/std/inplace_vector b/libstdc++-v3/include/std/inplace_vector
index 0096bd83a175602adf0609304969127fd68fdc4d..caf9c2032452c9bc906db29058870d705d9dc8bb 100644 (file)
--- a/libstdc++-v3/include/std/inplace_vector
+++ b/libstdc++-v3/include/std/inplace_vector
@@ -41,7 +41,7 @@
 #include <optional>
 #include <bits/stdexcept_throw.h>
 #include <bits/range_access.h>
-#include <bits/ranges_base.h> // borrowed_iterator_t, __detail::__container_compatible_range
+#include <bits/ranges_base.h> // borrowed_iterator_t, __detail::__container_compatible_range, __static_sized_range
 #include <bits/ranges_util.h> // subrange
 #include <bits/ranges_uninitialized.h>
 #include <bits/stl_construct.h>
@@ -120,7 +120,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
        constexpr
        inplace_vector(from_range_t, _Rg&& __rg)
        : inplace_vector()
-       { append_range(__rg); }
+       { 
+         // _GLIBCXX_RESOLVE_LIB_DEFECTS
+         // 4396. Improve inplace_vector(from_range_t, R&& rg)
+         if constexpr (ranges::__static_sized_range<_Rg>)
+           static_assert(ranges::size(__rg) <= _Nm);
+
+         append_range(__rg);
+       }
 
       constexpr
       inplace_vector(initializer_list<_Tp> __il)
@@ -934,6 +941,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
        constexpr
        inplace_vector(from_range_t, _Rg&& __rg)
        {
+         // _GLIBCXX_RESOLVE_LIB_DEFECTS
+         // 4396. Improve inplace_vector(from_range_t, R&& rg)
+         if constexpr (ranges::__static_sized_range<_Rg>)
+           static_assert(ranges::size(__rg) == 0);
+
          if (ranges::begin(__rg) != ranges::end(__rg))
            __throw_bad_alloc();
        }

diff --git a/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc
new file mode 100644 (file)
index 0000000..ae0b961
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc
@@ -0,0 +1,46 @@
+// { dg-do compile { target c++26 } }
+// { dg-require-effective-target int128 }
+
+#include <array>
+#include <ranges>
+#include <span>
+#include <inplace_vector>
+
+template<typename Int, Int min, Int max = std::numeric_limits<Int>::max()>
+struct StaticIota : std::ranges::iota_view<Int, Int>
+{
+  using Base = std::ranges::iota_view<Int, Int>;
+  using size_type = std::ranges::range_size_t<Base>;
+
+  constexpr StaticIota() noexcept : Base(min, max) {}
+
+  constexpr static size_type
+  size()
+  { return size_type(max) - size_type(min); }
+};
+
+template<typename Range>
+constexpr std::ranges::ref_view<Range>
+ref_view(Range& rg)
+{ return std::ranges::ref_view<Range>(rg); }
+
+void
+test_all()
+{
+  StaticIota<__int128, 0, 12> m12;
+
+  std::inplace_vector<int, 15> tm1(std::from_range, m12);
+  std::inplace_vector<int, 15> tr1(std::from_range, ref_view(m12));
+
+  std::inplace_vector<int, 10> tm2(std::from_range, m12); // { dg-error "(from here|expansion of)" }
+  // ref_view is not statically sized due pointer dereference
+  std::inplace_vector<int, 10> tr2(std::from_range, ref_view(m12));
+
+  StaticIota<__int128, 0> mm;
+
+  std::inplace_vector<int, 10> tm3(std::from_range, mm); // { dg-error "(from here|expansion of)" }
+  // ref_view is not statically sized due pointer dereference
+  std::inplace_vector<int, 10> tr3(std::from_range, ref_view(mm));
+}
+
+// { dg-error "static assertion failed" "" { target *-*-* } 0 }

diff --git a/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_range_neg.cc b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_range_neg.cc
new file mode 100644 (file)
index 0000000..48d5b4c
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_range_neg.cc
@@ -0,0 +1,78 @@
+// { dg-do compile { target c++26 } }
+
+#include <array>
+#include <ranges>
+#include <span>
+#include <inplace_vector>
+
+template<typename Range0>
+void
+test_zero(Range0&& r0)
+{
+  std::inplace_vector<int, 0> f0(std::from_range, r0);
+  std::inplace_vector<int, 1> f1(std::from_range, r0);
+  std::inplace_vector<int, 5> f5(std::from_range, r0);
+  std::inplace_vector<int, 7> f7(std::from_range, r0);
+}
+
+template<typename Range1>
+void
+test_one(Range1&& r1)
+{
+  std::inplace_vector<int, 0> f0(std::from_range, r1); // { dg-error "required from" }
+  std::inplace_vector<int, 1> f1(std::from_range, r1);
+  std::inplace_vector<int, 5> f5(std::from_range, r1);
+  std::inplace_vector<int, 7> f7(std::from_range, r1);
+}
+
+template<typename Range5>
+void
+test_five(Range5&& r5)
+{
+  std::inplace_vector<int, 0> f0(std::from_range, r5); // { dg-error "required from" }
+  std::inplace_vector<int, 1> f1(std::from_range, r5); // { dg-error "required from" }
+  std::inplace_vector<int, 3> f3(std::from_range, r5); // { dg-error "required from" }
+  std::inplace_vector<int, 5> f5(std::from_range, r5);
+  std::inplace_vector<int, 7> f7(std::from_range, r5);
+}
+
+template<typename Range>
+constexpr std::ranges::ref_view<Range>
+ref_view(Range& rg)
+{ return std::ranges::ref_view<Range>(rg); }
+
+void
+test_all()
+{
+  std::array<int, 0> a0;
+  std::span<int, 0> s0(a0);
+  std::array<int, 1> a1;
+  std::span<int, 1> s1(a1);
+  std::array<int, 5> a5;
+  std::span<int, 5> s5(a5);
+  std::array<int, 7> a7;
+  std::span<int, 7> s7(a7);
+
+  test_zero(a0);
+  test_zero(s0);
+  test_zero(ref_view(a0));
+  test_zero(std::views::empty<int>);
+  test_zero(s5 | std::views::adjacent<7> | std::views::elements<0>);
+  test_zero(a5 | std::views::adjacent<7> | std::views::elements<0>);
+
+  test_one(a1); // { dg-error "from here" }
+  test_one(s1); // { dg-error "from here" }
+  // ref_view is not statically sized due pointer dereference
+  test_one(ref_view(a1));
+  test_one(a5 | std::views::adjacent<7> | std::views::elements<0>);
+  test_one(s5 | std::views::adjacent<5> | std::views::elements<0>); // { dg-error "from here" }
+
+  test_five(a5); // { dg-error "from here" }
+  test_five(s5); // { dg-error "from here" }
+  // ref_view is not statically sized due pointer dereference
+  test_five(ref_view(a5));
+  test_five(a7 | std::views::adjacent<3> | std::views::elements<0>);
+  test_five(s7 | std::views::adjacent<3> | std::views::elements<0>); // { dg-error "from here" }
+}
+
+// { dg-error "static assertion failed" "" { target *-*-* } 0 }