diff --git a/libstdc++-v3/include/bits/chrono_io.h b/libstdc++-v3/include/bits/chrono_io.h index c95301361d877f1d168b7fe7316222c271b4e8d7..c422435f7f31dc3a3bedda0f86e2f9e8b8397677 100644 --- a/libstdc++-v3/include/bits/chrono_io.h +++ b/libstdc++-v3/include/bits/chrono_io.h @@ -826,9 +826,14 @@ namespace __format if (__conv == 'Y' || __conv == 'C') { - if (__is_neg) - __s.assign(1, _S_plus_minus[1]); int __ci = __yi / 100; + if (__is_neg) [[unlikely]] + { + __s.assign(1, _S_plus_minus[1]); + // For floored division -123//100 is -2 and -100//100 is -1 + if ((__ci * 100) != __yi) + ++__ci; + } if (__ci >= 100) [[unlikely]] { __s += std::format(_S_empty_spec, __ci / 100); diff --git a/libstdc++-v3/testsuite/std/time/year/io.cc b/libstdc++-v3/testsuite/std/time/year/io.cc index 89ab7b1e61e16b46ad6a5fcaf201c9fdb831187f..b50d9d89c614ccaf2c80b9b07f9d8b5155c0d0fe 100644 --- a/libstdc++-v3/testsuite/std/time/year/io.cc +++ b/libstdc++-v3/testsuite/std/time/year/io.cc @@ -44,8 +44,11 @@ test_format() s = std::format("{}", --year::min()); // formatted via ostream VERIFY( s == "-32768 is not a valid year" ); - s = std::format("{:%y} {:%y}", 1976y, -1976y); - VERIFY( s == "76 76" ); // LWG 3831 + s = std::format("{:%C %y} {:%C %y}", 1976y, -1976y); + VERIFY( s == "19 76 -20 76" ); // LWG 3831 + + s = std::format("{:%C %y} {:%C %y} {:%C %y}", -9y, -900y, -555y); + VERIFY( s == "-01 09 -09 00 -06 55" ); // LWG 4022 s = std::format("{0:%EC}{0:%Ey} = {0:%EY}", 1642y); VERIFY( s == "1642 = 1642" );