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List:       apache-stdcxx-issues
Subject:    [jira] [Closed] (STDCXX-1059) std::ios_base::setf() and std::ios_base::unsetf() do not set/clear the
From:       "Stefan Teleman (JIRA)" <jira () apache ! org>
Date:       2012-09-26 0:00:07
Message-ID: 490333597.126007.1348617607765.JavaMail.jiratomcat () arcas
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     [ https://issues.apache.org/jira/browse/STDCXX-1059?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel \
]

Stefan Teleman closed STDCXX-1059.
----------------------------------

    Resolution: Won't Fix

Upstream refuses to consider this a bug, in spite of the evidence.

                
> std::ios_base::setf() and std::ios_base::unsetf() do not set/clear the format flags \
>                 correctly
> ---------------------------------------------------------------------------------------------
>  
> Key: STDCXX-1059
> URL: https://issues.apache.org/jira/browse/STDCXX-1059
> Project: C++ Standard Library
> Issue Type: Bug
> Components: 27. Input/Output
> Affects Versions: 4.2.1, 4.2.x, 4.3.x, 5.0.0
> Environment: Solaris 10 and 11
> Red Hat Linux, OpenSuSE Linux
> Sun C++ Compilers 12.1, 12.2, 12.3
> Defect is independent of platform and/or compiler
> Reporter: Stefan Teleman
> Labels: conformance, runtime, standards
> Fix For: 4.2.2, 4.2.x, 4.3.x, 5.0.0
> 
> Attachments: flags.cc, test.cc
> 
> 
> std::ios_base::setf (fmtflags fl) and std::ios_base::unsetf (fmtflags fl)
> do not set or clear the format flags correctly:
> {code:title=test.cc|borderStyle=solid}
> #include <ios>
> #include <iostream>
> #include <fstream>
> int main()
> {
> std::fstream strm;
> std::ios_base::fmtflags fl;
> int ret = 0;
> fl = std::ios_base::dec;
> strm.unsetf(fl);
> fl = std::ios_base::hex;
> strm.setf(fl);
> strm.unsetf(fl);
> if (strm.flags() & fl)
> {
> std::cerr << "failure to clear hex flags" << std::endl;
> ++ret;
> }
> return ret;
> }
> {code}
> 1. Output from GCC 4.5.0:
> {noformat}
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
> 15:19:37][1957]>> ./test-gcc  \
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
> 15:20:02][1958]>> echo $status 0
> {noformat}
> 2. Output from Sun C++ 12.2 with stlport:
> {noformat}
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
> 15:20:24][1959]>> ./test-ss122-stlport  \
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
> 15:21:08][1960]>> echo $status 0
> {noformat}
> 3. Output rom Sun C++ 12.2 with our patched stdcxx:
> {noformat}
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
> 15:21:09][1961]>> ./test-ss122-stdcxx  \
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
> 15:21:44][1962]>> echo $status 0
> {noformat}
> 4. Output from Pathscale 4.0.12.1 (which did not patch stdcxx):
> {noformat}
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
> 15:21:46][1963]>> ./test-pathscale  failure to clear hex flags
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
> 15:22:48][1964]>> echo $status 1
> {noformat}
> Simplified test case identifying the problem:
> {code:title=flags.cc|borderStyle=solid}
> #include <iostream>
> #include <ios>
> class BadTest
> {
> public:
> BadTest() : _flags(0) { }
> ~BadTest() { }
> unsigned int flags() const { return _flags; }
> unsigned int flags (unsigned int f)
> {
> unsigned int ret = _flags;
> _flags |= f;
> return ret;
> }
> unsigned int setf (unsigned int f) { return flags (flags() | f); }
> void unsetf (unsigned int f) { flags (flags() & ~f); }
> private:
> unsigned int _flags;
> };
> class GoodTest
> {
> public:
> GoodTest() : _flags(0) { }
> ~GoodTest() { }
> unsigned int flags() const { return _flags; }
> unsigned int flags (unsigned int f)
> {
> unsigned int ret = _flags;
> _flags |= f;
> return ret;
> }
> unsigned int setf (unsigned int f)
> {
> unsigned int ret = _flags;
> _flags |= f;
> return ret;
> }
> void unsetf (unsigned int f) { _flags &= ~f; }
> private:
> unsigned int _flags;
> };
> int main()
> {
> BadTest bt;
> std::ios_base::fmtflags fl;
> std::cerr << "***** BadTest *****" << std::endl;
> std::cerr << "default flags: " << bt.flags() << std::endl;
> fl = std::ios_base::dec;
> bt.setf(fl);
> std::cerr << "flags: " << bt.flags() << std::endl;
> bt.unsetf(fl);
> std::cerr << "flags: " << bt.flags() << std::endl;
> fl = std::ios_base::hex;
> bt.setf(fl);
> std::cerr << "flags: " << bt.flags() << std::endl;
> bt.unsetf(fl);
> std::cerr << "flags: " << bt.flags() << std::endl;
> std::cerr << std::endl;
> GoodTest gt;
> std::cerr << "***** GoodTest *****" << std::endl;
> std::cerr << "default flags: " << gt.flags() << std::endl;
> fl = std::ios_base::dec;
> gt.setf(fl);
> std::cerr << "flags: " << gt.flags() << std::endl;
> gt.unsetf(fl);
> std::cerr << "flags: " << gt.flags() << std::endl;
> fl = std::ios_base::hex;
> gt.setf(fl);
> std::cerr << "flags: " << gt.flags() << std::endl;
> gt.unsetf(fl);
> std::cerr << "flags: " << gt.flags() << std::endl;
> return 0;
> }
> {code}
> 1. Output from GCC 4.5.0:
> {noformat}
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
>                 15:27:01][1968]>> ./flags-gcc 
> ***** BadTest *****
> default flags: 0
> flags: 2
> flags: 2
> flags: 10
> flags: 10
> ***** GoodTest *****
> default flags: 0
> flags: 2
> flags: 0
> flags: 8
> flags: 0
> {noformat}
> 2. Output from Sun C++ 12.2 with stlport:
> {noformat}
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
>                 15:27:05][1969]>> ./flags-ss122-stlport 
> ***** BadTest *****
> default flags: 0
> flags: 8
> flags: 8
> flags: 24
> flags: 24
> ***** GoodTest *****
> default flags: 0
> flags: 8
> flags: 0
> flags: 16
> flags: 0
> {noformat}
> 3. Output from Sun C++ 12.2. with our patched stdcxx:
> {noformat}
> [steleman@darthvader][/src/steleman/programming/stdcxx-ss122/bugfixes-sunw/fmtflags][02/05/2012 \
>                 15:27:12][1970]>> ./flags-ss122-stdcxx 
> ***** BadTest *****
> default flags: 0
> flags: 2
> flags: 2
> flags: 10
> flags: 10
> ***** GoodTest *****
> default flags: 0
> flags: 2
> flags: 0
> flags: 8
> flags: 0
> {noformat}
> The defect is in
> {noformat}
> std::ios_base::setf(fmtflags fl);
> and
> std::ios_base::unsetf(fmtflags fl);
> {noformat}
> in the original stdcxx implementation. The member function
> {noformat}
> fmtflags std::ios_base::flags() const;
> {noformat}
> returns by value. Any bitwise operations on the anon temporary created by
> this function do not affect the __fmtflags data member of std::ios_base,
> which remains unchanged.
> Patch for stdcxx 4.2.1 to follow.

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