diff options
| author | Jonathan Wakely <jwakely@redhat.com> | 2023-12-11 15:33:59 +0000 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2023-12-12 22:33:32 +0000 |
| commit | a01462ae8bafa86e7df47a252917ba6899d587cf (patch) | |
| tree | 82f8a46d4a2062aa0218c745b696479596e48ec5 | |
| parent | 988dd6384c88a110952833dfe7c8344b9af95fa4 (diff) | |
| download | gcc-a01462ae8bafa86e7df47a252917ba6899d587cf.zip gcc-a01462ae8bafa86e7df47a252917ba6899d587cf.tar.gz gcc-a01462ae8bafa86e7df47a252917ba6899d587cf.tar.bz2 | |
libstdc++: Fix std::format output of %C for negative years
During discussion of LWG 4022 I noticed that we do not correctly
implement floored division for the century. We were just truncating
towards zero, rather than applying the floor function. For negative
values that rounds the wrong way.
libstdc++-v3/ChangeLog:
* include/bits/chrono_io.h (__formatter_chrono::_M_C_y_Y): Fix
rounding for negative centuries.
* testsuite/std/time/year/io.cc: Check %C for negative years.
| -rw-r--r-- | libstdc++-v3/include/bits/chrono_io.h | 9 | ||||
| -rw-r--r-- | libstdc++-v3/testsuite/std/time/year/io.cc | 7 |
2 files changed, 12 insertions, 4 deletions
diff --git a/libstdc++-v3/include/bits/chrono_io.h b/libstdc++-v3/include/bits/chrono_io.h index 16e8fc5..b63b859 100644 --- a/libstdc++-v3/include/bits/chrono_io.h +++ b/libstdc++-v3/include/bits/chrono_io.h @@ -820,9 +820,14 @@ 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 6157afa..a6683ae 100644 --- a/libstdc++-v3/testsuite/std/time/year/io.cc +++ b/libstdc++-v3/testsuite/std/time/year/io.cc @@ -43,8 +43,11 @@ 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" ); |