This PR attempts to implement P3798 (The unexpected in std::expected).
LEWG recommended this as DR for C++23
(https://github.com/cplusplus/papers/issues/2403, see poll).
Implementation in libc++ is merged here:
https://github.com/llvm/llvm-project/pull/204826
Please advise on any documentation, tests and/or other changes that are needed
to successfully land this change.
Thanks,
Alex
---
libstdc++-v3/include/bits/version.def | 5 +++--
libstdc++-v3/include/bits/version.h | 4 ++--
libstdc++-v3/include/std/expected | 6 ++++++
.../testsuite/20_util/expected/observers.cc | 18 ++++++++++++++++++
.../testsuite/20_util/expected/synopsis.cc | 2 +-
.../testsuite/20_util/expected/version.cc | 4 ++--
6 files changed, 32 insertions(+), 7 deletions(-)
diff --git a/libstdc++-v3/include/bits/version.def
b/libstdc++-v3/include/bits/version.def
index 40baefab4e4..d54f331d9f2 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -1594,9 +1594,10 @@ ftms = {
ftms = {
name = expected;
+ // 202606 P3798R1 The unexpected in std::expected
values = {
- v = 202211;
- cxxmin = 23;
+ v = 202606;
+ cxxmin = 23; // P3798R1 is C++29 but is accepted as DR for C++23
extra_cond = "__cpp_concepts >= 202002L";
};
};
diff --git a/libstdc++-v3/include/bits/version.h
b/libstdc++-v3/include/bits/version.h
index de1d71fa935..fe79f448938 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -1743,9 +1743,9 @@
#if !defined(__cpp_lib_expected)
# if (__cplusplus >= 202100L) && (__cpp_concepts >= 202002L)
-# define __glibcxx_expected 202211L
+# define __glibcxx_expected 202606L
# if defined(__glibcxx_want_all) || defined(__glibcxx_want_expected)
-# define __cpp_lib_expected 202211L
+# define __cpp_lib_expected 202606L
# endif
# endif
#endif /* !defined(__cpp_lib_expected) */
diff --git a/libstdc++-v3/include/std/expected
b/libstdc++-v3/include/std/expected
index fe4e1ecbf0e..7f8d0d37501 100644
--- a/libstdc++-v3/include/std/expected
+++ b/libstdc++-v3/include/std/expected
@@ -855,6 +855,9 @@ namespace __expected
_GLIBCXX_THROW_OR_ABORT(bad_expected_access<_Er>(std::move(_M_unex)));
}
+ [[nodiscard]]
+ constexpr bool has_error() const noexcept { return !has_value(); }
+
constexpr const _Er&
error() const & noexcept
{
@@ -1642,6 +1645,9 @@ namespace __expected
_GLIBCXX_THROW_OR_ABORT(bad_expected_access<_Er>(std::move(_M_unex)));
}
+ [[nodiscard]]
+ constexpr bool has_error() const noexcept { return !has_value(); }
+
constexpr const _Er&
error() const & noexcept
{
diff --git a/libstdc++-v3/testsuite/20_util/expected/observers.cc
b/libstdc++-v3/testsuite/20_util/expected/observers.cc
index 31aaca352ae..84bce2eca52 100644
--- a/libstdc++-v3/testsuite/20_util/expected/observers.cc
+++ b/libstdc++-v3/testsuite/20_util/expected/observers.cc
@@ -59,6 +59,22 @@ test_has_value()
return true;
}
+constexpr bool
+test_has_error()
+{
+ std::expected<int, int> e;
+ VERIFY( ! e.has_error() );
+ e = std::unexpected(1);
+ VERIFY( e.has_error() );
+
+ std::expected<void, int> v;
+ VERIFY( ! v.has_error() );
+ v = std::unexpected(1);
+ VERIFY( v.has_error() );
+
+ return true;
+}
+
constexpr bool
test_value()
{
@@ -222,6 +238,8 @@ int main()
test_star();
static_assert( test_has_value() );
test_has_value();
+ static_assert( test_has_error() );
+ test_has_error();
static_assert( test_value() );
test_value();
#if __cpp_lib_constexpr_exceptions >= 202502L
diff --git a/libstdc++-v3/testsuite/20_util/expected/synopsis.cc
b/libstdc++-v3/testsuite/20_util/expected/synopsis.cc
index a0d2d5bea22..8866af7887f 100644
--- a/libstdc++-v3/testsuite/20_util/expected/synopsis.cc
+++ b/libstdc++-v3/testsuite/20_util/expected/synopsis.cc
@@ -6,7 +6,7 @@
#ifndef __cpp_lib_expected
# error "Feature-test macro for expected missing in <expected>"
-#elif __cpp_lib_expected != 202211L
+#elif __cpp_lib_expected != 202606L
# error "Feature-test macro for expected has wrong value in <expected>"
#endif
diff --git a/libstdc++-v3/testsuite/20_util/expected/version.cc
b/libstdc++-v3/testsuite/20_util/expected/version.cc
index 17c7fe4a5d6..f9b3011727f 100644
--- a/libstdc++-v3/testsuite/20_util/expected/version.cc
+++ b/libstdc++-v3/testsuite/20_util/expected/version.cc
@@ -5,7 +5,7 @@
#ifndef __cpp_lib_expected
# error "Feature-test macro for expected missing in <version>"
-#elif __cpp_lib_expected != 202211L
+#elif __cpp_lib_expected != 202606L
# error "Feature-test macro for expected has wrong value in <version>"
#endif
@@ -30,7 +30,7 @@
#ifndef __cpp_lib_expected
# error "Feature-test macro for expected missing in <expected>"
-#elif __cpp_lib_expected != 202211L
+#elif __cpp_lib_expected != 202606L
# error "Feature-test macro for expected has wrong value in <expected>"
#endif
--
2.51.0
