From 40b0d4472a2591cf27f3a81aa3fba57dc4532648 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Mon, 17 Jan 2022 14:32:30 -0500 Subject: libstdc++: Adjust fast_float's over/underflow behavior for conformance This changes fast_float's handling of overflow/underflow to be consistent with the standard: instead of returning errc{} and setting value to +-0 or +-infinity, just return errc::result_out_of_range and don't modify value, as per [charconv.from.chars]/1. libstdc++-v3/ChangeLog: * src/c++17/fast_float/LOCAL_PATCHES: Update. * src/c++17/fast_float/fast_float.h (from_chars_advanced): In case of over/underflow, return errc::result_out_of_range and don't modify 'value'. --- libstdc++-v3/src/c++17/fast_float/LOCAL_PATCHES | 1 + libstdc++-v3/src/c++17/fast_float/fast_float.h | 9 +++++++++ 2 files changed, 10 insertions(+) (limited to 'libstdc++-v3/src/c++17') diff --git a/libstdc++-v3/src/c++17/fast_float/LOCAL_PATCHES b/libstdc++-v3/src/c++17/fast_float/LOCAL_PATCHES index ad5a60f9a01..71495d6728b 100644 --- a/libstdc++-v3/src/c++17/fast_float/LOCAL_PATCHES +++ b/libstdc++-v3/src/c++17/fast_float/LOCAL_PATCHES @@ -1 +1,2 @@ r12-6647 +r12-6648 diff --git a/libstdc++-v3/src/c++17/fast_float/fast_float.h b/libstdc++-v3/src/c++17/fast_float/fast_float.h index c908719ec3a..97d28940944 100644 --- a/libstdc++-v3/src/c++17/fast_float/fast_float.h +++ b/libstdc++-v3/src/c++17/fast_float/fast_float.h @@ -2884,6 +2884,15 @@ from_chars_result from_chars_advanced(const char *first, const char *last, // If we called compute_float>(pns.exponent, pns.mantissa) and we have an invalid power (am.power2 < 0), // then we need to go the long way around again. This is very uncommon. if(am.power2 < 0) { am = digit_comp(pns, am); } + + if((pns.mantissa != 0 && am.mantissa == 0 && am.power2 == 0) || am.power2 == binary_format::infinite_power()) { + // In case of over/underflow, return result_out_of_range and don't modify value, + // as per [charconv.from.chars]/1. Note that LWG 3081 wants to modify value in + // this case too. + answer.ec = std::errc::result_out_of_range; + return answer; + } + to_float(pns.negative, am, value); return answer; } -- cgit v1.2.3