https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84216
Bug ID: 84216
Summary: std::get_time fails to parse output from
std::put_time, but strptime can parse them (c++11)
Product: gcc
Version: 7.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: dkstrickland2 at gmail dot com
Target Milestone: ---
Created attachment 43341
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43341&action=edit
code to reproduce get_time issues
The std::get_time() function in g++/libc++ (version 7.2.1, Fedora linux 27)
fails to correctly parse date/time strings that std::put_time correctly
produces.
In some cases both time and date are incorrect, at other times the date is
incorrect. When this occurs std::get_time is setting the stream's fail() flag,
which is better than nothing, but it seems like a bug that get_time cannot
parse what put_time produces. Note that strptime does correctly parse the
output of put_time.
At a lesser level of problem, when get_time does successfully parse the
date/time string the std::tm struct is not identical to the original fed to
std::put_time, whereas strptime does seem to produce an output std::tm that
matches the original.
I get the same problems on the online Coliru c++ compiler with g++ version 7.1
(c++11 and later) and 5.2 (c++11).
The output of the attached code is as follows (somewhat lengthy):
Testing std::get_time() ---------------------------
Testing format: %Y %m %d %T
Result of put_time on tm1: 2008 01 02 12:23:45
WARN: Struct from get_time, tm2!=tm1. Possible BUG?.
Result of put_time on tm2: 2008 01 02 12:23:45
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %F %T
Result of put_time on tm1: 2008-01-02 12:23:45
WARN: get_time parse sets stream fail bit.
WARN: Struct from get_time, tm2!=tm1. Possible BUG?.
Result of put_time on tm2: 1900-01-00 00:00:00
ERROR: String repr of get_time tm2 != string repr of tm1. BUG?.
Testing format: %Y-%j %X %z
Result of put_time on tm1: 2008-002 12:23:45 +0000
WARN: get_time parse sets stream fail bit.
WARN: Struct from get_time, tm2!=tm1. Possible BUG?.
Result of put_time on tm2: 2008-001 00:00:00 +0000
ERROR: String repr of get_time tm2 != string repr of tm1. BUG?.
Testing format: %c %Z
Result of put_time on tm1: Wed Jan 2 12:23:45 2008 EST
WARN: get_time parse sets stream fail bit.
WARN: Struct from get_time, tm2!=tm1. Possible BUG?.
Result of put_time on tm2: Sun Jan 0 00:00:00 1900 EST
ERROR: String repr of get_time tm2 != string repr of tm1. BUG?.
Testing format: %x
Result of put_time on tm1: 01/02/08
WARN: Struct from get_time, tm2!=tm1. Possible BUG?.
Result of put_time on tm2: 01/02/08
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %Y-%m-%d %H:%M:%S
Result of put_time on tm1: 2008-01-02 12:23:45
WARN: Struct from get_time, tm2!=tm1. Possible BUG?.
Result of put_time on tm2: 2008-01-02 12:23:45
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %y-%m-%d %T
Result of put_time on tm1: 08-01-02 12:23:45
WARN: Struct from get_time, tm2!=tm1. Possible BUG?.
Result of put_time on tm2: 08-01-02 12:23:45
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %a %b %e %T %Z %Y
Result of put_time on tm1: Wed Jan 2 12:23:45 EST 2008
WARN: get_time parse sets stream fail bit.
WARN: Struct from get_time, tm2!=tm1. Possible BUG?.
Result of put_time on tm2: Wed Jan 0 00:00:00 EST 1900
ERROR: String repr of get_time tm2 != string repr of tm1. BUG?.
4 tests fail and 4 pass.
Passing format strings:
%Y %m %d %T
%x
%Y-%m-%d %H:%M:%S
%y-%m-%d %T
Definitely failing format strings:
%F %T
%Y-%j %X %z
%c %Z
%a %b %e %T %Z %Y
Testing strptime() --------------------------------
Testing format: %Y %m %d %T
Result of put_time on tm1: 2008 01 02 12:23:45
Struct from get_time, tm2==tm1. OK.
Result of put_time on tm2: 2008 01 02 12:23:45
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %F %T
Result of put_time on tm1: 2008-01-02 12:23:45
Struct from get_time, tm2==tm1. OK.
Result of put_time on tm2: 2008-01-02 12:23:45
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %Y-%j %X %z
Result of put_time on tm1: 2008-002 12:23:45 +0000
Struct from get_time, tm2==tm1. OK.
Result of put_time on tm2: 2008-002 12:23:45 +0000
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %c %Z
Result of put_time on tm1: Wed Jan 2 12:23:45 2008 EST
Struct from get_time, tm2==tm1. OK.
Result of put_time on tm2: Wed Jan 2 12:23:45 2008 EST
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %x
Result of put_time on tm1: 01/02/08
WARN: Struct from get_time, tm2!=tm1. Possible BUG?.
Result of put_time on tm2: 01/02/08
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %Y-%m-%d %H:%M:%S
Result of put_time on tm1: 2008-01-02 12:23:45
Struct from get_time, tm2==tm1. OK.
Result of put_time on tm2: 2008-01-02 12:23:45
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %y-%m-%d %T
Result of put_time on tm1: 08-01-02 12:23:45
Struct from get_time, tm2==tm1. OK.
Result of put_time on tm2: 08-01-02 12:23:45
OK: String repr of get_time tm2 == string repr of tm1.
Testing format: %a %b %e %T %Z %Y
Result of put_time on tm1: Wed Jan 2 12:23:45 EST 2008
Struct from get_time, tm2==tm1. OK.
Result of put_time on tm2: Wed Jan 2 12:23:45 EST 2008
OK: String repr of get_time tm2 == string repr of tm1.
0 tests fail and 8 pass.
Passing format strings:
%Y %m %d %T
%F %T
%Y-%j %X %z
%c %Z
%x
%Y-%m-%d %H:%M:%S
%y-%m-%d %T
%a %b %e %T %Z %Y
Results -------------------------------------------
get_time fails to parse put_time output 4 times.
strptime fails to parse put_time output 0 times.
