From 9f0e33bc83c2924e2af29aa76de7cbd6169dafaf Mon Sep 17 00:00:00 2001
From: Igor Zhukov <fsb4000@yandex.ru>
Date: Sat, 16 Apr 2022 07:38:10 +0700
Subject: [PATCH] fix `treat_as_floating_point_v<_DurationType>` (#2638)
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Co-authored-by: Daniel Krügler <daniel.kruegler@gmail.com>
Co-authored-by: Stephan T. Lavavej <stl@nuwen.net>
---
 stl/inc/chrono                                     | 14 ++++++++------
 .../P0355R7_calendars_and_time_zones_io/test.cpp   |  4 ++++
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/stl/inc/chrono b/stl/inc/chrono
index 3cdeb670f..2d6b6a025 100644
--- a/stl/inc/chrono
+++ b/stl/inc/chrono
@@ -3387,14 +3387,16 @@ namespace chrono {
             if constexpr (_Can_rep_sec) {
                 if (_Used & _F_sec) {
                     if (_Subsecond) {
-                        using _CastedType = duration<int64_t, typename _DurationType::period>;
                         const _SubsecondType _Sub{*_Subsecond};
-                        if (treat_as_floating_point_v<_DurationType> //
-                            || _CHRONO duration_cast<_CastedType>(_Sub) == _Sub) {
-                            _Result += _CHRONO duration_cast<_DurationType>(_Sub);
-                        } else {
-                            return false;
+
+                        if constexpr (!treat_as_floating_point_v<typename _DurationType::rep>) {
+                            using _CastedType = duration<int64_t, typename _DurationType::period>;
+                            if (_CHRONO duration_cast<_CastedType>(_Sub) != _Sub) {
+                                return false;
+                            }
                         }
+
+                        _Result += _CHRONO duration_cast<_DurationType>(_Sub);
                     }
 
                     if (_Second) {
diff --git a/tests/std/tests/P0355R7_calendars_and_time_zones_io/test.cpp b/tests/std/tests/P0355R7_calendars_and_time_zones_io/test.cpp
index fd8341823..879e7a67e 100644
--- a/tests/std/tests/P0355R7_calendars_and_time_zones_io/test.cpp
+++ b/tests/std/tests/P0355R7_calendars_and_time_zones_io/test.cpp
@@ -259,6 +259,10 @@ void parse_seconds() {
     test_parse("0.400000000000000002", "%S", time_atto);
     assert((time_atto == duration<int64_t, deci>{4} + duration<int64_t, atto>{2}));
 
+    duration<float, ratio<1, 25>> time_float;
+    test_parse("0.33", "%S", time_float);
+    assert((time_float == duration<float, ratio<1, 25>>{8.25f}));
+
     fail_parse("1.2 1.3", "%S %S", time_ms);
     fail_parse("1.2 2.2", "%S %S", time_ms);
 }