[gcc r13-6806] libstdc++: Add allocator-extended constructors to std::match_results (LWG 2195)

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:9ae1108196ed65647846a7c06052317e8fa4852d

commit r13-6806-g9ae1108196ed65647846a7c06052317e8fa4852d
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Mar 22 11:36:06 2023 +0000

    libstdc++: Add allocator-extended constructors to std::match_results (LWG 2195)
    
    This was approved in Issaquah last month.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/regex.h (match_results): Add allocator-extended
            copy and move constructors, as per LWG 2195.
            * testsuite/28_regex/match_results/ctors/char/alloc.cc: New test.

Diff:
---
 libstdc++-v3/include/bits/regex.h                  | 10 ++++
 .../28_regex/match_results/ctors/char/alloc.cc     | 56 ++++++++++++++++++++++
 2 files changed, 66 insertions(+)

diff --git a/libstdc++-v3/include/bits/regex.h b/libstdc++-v3/include/bits/regex.h
index 386f4be9f4a..79903fad1e5 100644
--- a/libstdc++-v3/include/bits/regex.h
+++ b/libstdc++-v3/include/bits/regex.h
@@ -1826,6 +1826,16 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
        */
       ~match_results() = default;
 
+      // _GLIBCXX_RESOLVE_LIB_DEFECTS
+      // 2195. Missing constructors for match_results
+
+      match_results(const match_results& __m, const _Alloc& __a)
+      : _Base_type(__m, __a) { }
+
+      match_results(match_results&& __m, const _Alloc& __a)
+      noexcept(noexcept(_Base_type(std::move(__m), __a)))
+      : _Base_type(std::move(__m), __a) { }
+
       ///@}
 
       // 28.10.2, state:
diff --git a/libstdc++-v3/testsuite/28_regex/match_results/ctors/char/alloc.cc b/libstdc++-v3/testsuite/28_regex/match_results/ctors/char/alloc.cc
new file mode 100644
index 00000000000..bb5e7a91bd7
--- /dev/null
+++ b/libstdc++-v3/testsuite/28_regex/match_results/ctors/char/alloc.cc
@@ -0,0 +1,56 @@
+// { dg-do run { target c++11 } }
+
+#include <regex>
+#include <testsuite_hooks.h>
+#include <testsuite_allocator.h>
+
+// LWG 2195. Missing constructors for match_results
+
+void
+test01()
+{
+  using Alloc = std::cmatch::allocator_type;
+  std::cmatch m1;
+  std::cmatch m2(m1, m1.get_allocator());
+  VERIFY( m2 == m1 );
+
+  static_assert( ! std::is_nothrow_constructible<std::cmatch,
+						 const std::cmatch&,
+						 const Alloc&>(),
+		 "Allocator-extended copy ctor is potentially-throwing" );
+
+  std::cmatch m3(std::move(m1), m2.get_allocator());
+  VERIFY( m3 == m2 );
+
+  // Libstdc++ extension:
+  static_assert( std::is_nothrow_constructible<std::cmatch,
+					       std::cmatch,
+					       const Alloc&>(),
+		 "Allocator-extended move ctor is non-throwing" );
+}
+
+void
+test02()
+{
+  using Alloc = __gnu_test::uneq_allocator<std::csub_match>;
+  using MR = std::match_results<const char*, Alloc>;
+
+  MR m1(Alloc(1));
+  MR m2(m1, Alloc(2));
+  VERIFY( m2 == m1 );
+
+  static_assert( ! std::is_nothrow_constructible<MR, const MR&, const Alloc&>(),
+		 "Allocator-extended copy ctor is potentially-throwing" );
+
+  MR m3(std::move(m1), Alloc(3));
+  VERIFY( m3 == m2 );
+
+  static_assert( ! std::is_nothrow_constructible<MR, MR, const Alloc&>(),
+		 "Allocator-extended move ctor is potentially-throwing" );
+}
+
+int main()
+{
+  test01();
+  test02();
+}