On Tue, 30 Jun 2026 at 15:39, Tomasz Kamiński <[email protected]> wrote:
>
> From: Anlai Lu <[email protected]>
>
> Add tests covering formatted output function semantics for the
> chrono operator<< overloads. These verify that the new stack-buffer
> implementation correctly preserves sentry construction (badbit check
> and tied stream flush), width/fill padding with all three alignment
> modes (right, left, internal), width reset after each output, and
> locale-aware output. A weekday_indexed content test and a wchar_t
> smoke test are included.
>
> libstdc++-v3/ChangeLog:
>
> * testsuite/std/time/ostream_insert.cc: New test.
>
> Reviewed-by: Tomasz Kamiński <[email protected]>
> Signed-off-by: Anlai Lu <[email protected]>
> ---
> Patch v3:
> * check prefixes in test_multiple_chrono_types (as I suggested)
> * add check_prefix funciton to simplify above
> * uses os.view() to extract the written characters
>
> Tested on x86_64-linux. OK for trunk?
>
> .../testsuite/std/time/ostream_insert.cc | 183 ++++++++++++++++++
> 1 file changed, 183 insertions(+)
> create mode 100644 libstdc++-v3/testsuite/std/time/ostream_insert.cc
>
> diff --git a/libstdc++-v3/testsuite/std/time/ostream_insert.cc
> b/libstdc++-v3/testsuite/std/time/ostream_insert.cc
> new file mode 100644
> index 00000000000..a78f7c1d162
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/std/time/ostream_insert.cc
> @@ -0,0 +1,183 @@
> +// { dg-do run { target c++20 } }
> +// { dg-require-effective-target tzdb }
This dg-require should not be here, the test doesn't require tzdb.
OK for trunk without that line.
> +// Test stream state semantics for chrono operator<<
> +#include <chrono>
> +#include <format>
> +#include <iomanip>
> +#include <sstream>
> +#include <testsuite_hooks.h>
> +
> +bool
> +check_prefix(std::string_view s, size_t n, char c)
> +{
> + for (char v : s)
> + if (v != c)
> + return !n;
> + else if (!n)
> + return false;
> + else
> + --n;
> + return false;
> +}
> +
> +void
> +test_sentry_badbit()
> +{
> + using namespace std::chrono;
> + std::ostringstream os;
> + os.setstate(std::ios::badbit);
> + VERIFY( !os.good() );
> + os << sys_time<seconds>{1'700'000'000s};
> + VERIFY( os.bad() );
> + VERIFY( os.str().empty() );
> +}
> +
> +void
> +test_sentry_tied()
> +{
> + using namespace std::chrono;
> + struct testbuf : std::streambuf
> + { bool flushed = false; int sync() override { flushed = true; return 0; }
> };
> + testbuf tied_buf; std::ostream tied(&tied_buf); std::ostringstream os;
> + os.tie(&tied);
> + os << sys_time<seconds>{1'700'000'000s};
> + VERIFY( tied_buf.flushed == true );
> +}
> +
> +void
> +test_width_fill()
> +{
> + using namespace std::chrono;
> + std::ostringstream os;
> + os << std::setw(30) << std::setfill('*') <<
> sys_time<seconds>{1'700'000'000s};
> + auto s = os.view();
> + VERIFY( s.size() == 30 );
> + VERIFY( check_prefix(s, 11, '*') );
> + VERIFY( s.substr(11) == "2023-11-14 22:13:20" );
> + VERIFY( os.width() == 0 );
> +}
> +
> +void
> +test_width_left()
> +{
> + using namespace std::chrono;
> + std::ostringstream os;
> + os << std::setw(30) << std::left << std::setfill('.') <<
> sys_time<seconds>{1'700'000'000s};
> + auto s = os.view();
> + VERIFY( s.size() == 30 );
> + VERIFY( s.find("2023-11-14") == 0 );
> + VERIFY( s.back() == '.' );
> + VERIFY( os.width() == 0 );
> +}
> +
> +void
> +test_width_internal()
> +{
> + using namespace std::chrono;
> + std::ostringstream os;
> + os << std::setw(30) << std::internal << std::setfill('_') << day(15);
> + auto s = os.view();
> + VERIFY( s.size() == 30 );
> + VERIFY( check_prefix(s, 28, '_') );
> + VERIFY( s.substr(28) == "15" );
> + VERIFY( os.width() == 0 );
> +}
> +
> +void
> +test_width_reset()
> +{
> + using namespace std::chrono;
> + std::ostringstream os;
> + os << std::setw(20) << sys_time<seconds>{1'700'000'000s};
> + VERIFY( os.width() == 0 );
> + os << hh_mm_ss{seconds(45296)};
> + VERIFY( os.width() == 0 );
> + os << std::setw(15) << day(15);
> + VERIFY( os.width() == 0 );
> +}
> +
> +void
> +test_width_zero()
> +{
> + using namespace std::chrono;
> + std::ostringstream os;
> + os << std::setw(0) << sys_time<seconds>{1'700'000'000s};
> + auto s = os.view();
> + VERIFY( s.find("2023-11-14") != std::string::npos );
> + VERIFY( s.size() < 20 );
> + VERIFY( os.width() == 0 );
> +}
> +
> +void
> +test_multiple_chrono_types()
> +{
> + using namespace std::chrono;
> + std::ostringstream os;
> + os << std::setw(25) << std::setfill('-') <<
> sys_time<seconds>{1'700'000'000s};
> + VERIFY( check_prefix(os.view(), 6, '-') );
> + VERIFY( os.width() == 0 );
> + os << std::setw(15) << hh_mm_ss{seconds(45296)};
> + VERIFY( check_prefix(os.view().substr(25), 7, '-') );
> + VERIFY( os.width() == 0 );
> + os << std::setw(10) << day(15);
> + VERIFY( check_prefix(os.view().substr(40), 8, '-') );
> + VERIFY( os.width() == 0 );
> + os << std::setw(10) << month(7);
> + VERIFY( check_prefix(os.view().substr(50), 7, '-') );
> + VERIFY( os.width() == 0 );
> + os << std::setw(10) << year(2026);
> + VERIFY( check_prefix(os.view().substr(60), 6, '-') );
> + VERIFY( os.width() == 0 );
> + os << std::setw(12) << Monday;
> + VERIFY( check_prefix(os.view().substr(70), 9, '-') );
> + VERIFY( os.width() == 0 );
> +}
> +
> +void
> +test_locale_aware()
> +{
> + using namespace std::chrono;
> + std::ostringstream os;
> + os.imbue(std::locale::classic());
> + os << std::setw(12) << Monday;
> + auto s = os.str();
> + VERIFY( s.size() >= 12 );
> + VERIFY( os.width() == 0 );
> +}
> +
> +void
> +test_wchar_t()
> +{
> + using namespace std::chrono;
> + std::wostringstream wos;
> + wos << std::chrono::sys_time<std::chrono::seconds>{1'700'000'000s};
> + VERIFY( wos.str() == L"2023-11-14 22:13:20" );
> +}
> +
> +void
> +test_weekday_indexed()
> +{
> + using namespace std::chrono;
> + std::ostringstream os;
> + os << Monday[1];
> + VERIFY( os.view() == "Mon[1]" );
> + os.str("");
> + os << Monday[6]; // invalid index
> + VERIFY( os.view().find("Mon[") != std::string::npos );
> +}
> +
> +int
> +main()
> +{
> + test_sentry_badbit();
> + test_sentry_tied();
> + test_width_fill();
> + test_width_left();
> + test_width_internal();
> + test_width_reset();
> + test_width_zero();
> + test_multiple_chrono_types();
> + test_locale_aware();
> + test_wchar_t();
> + test_weekday_indexed();
> +}
> --
> 2.54.0
>
