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libstdc++: Implement LWG 415 for std::ws

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For C++11 std::ws changed to be an unformatted input function, meaning
it constructs a sentry and sets badbit on exceptions.

libstdc++-v3/ChangeLog:

	* doc/xml/manual/intro.xml: Document LWG 415 change.
	* doc/html/manual/bugs.html: Regenerate.
	* include/bits/istream.tcc (ws): Create sentry and catch
	exceptions.
	* testsuite/27_io/basic_istream/ws/char/lwg415.cc: New test.
	* testsuite/27_io/basic_istream/ws/wchar_t/lwg415.cc: New test.
This commit is contained in:
Jonathan Wakely 2021-06-25 21:33:02 +01:00
parent b838641bb0
commit e5c422b7d8
5 changed files with 201 additions and 10 deletions
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4
libstdc++-v3/doc/html/manual/bugs.html
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@ -245,6 +245,10 @@
</p></dd><dt><a id="manual.bugs.dr409"></a><span class="term"><a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#409" target="_top">409</a>:
<span class="emphasis"><em>Closing an fstream should clear the error state</em></span>
</span></dt><dd><p>Have <code class="code">open</code> clear the error flags.
</p></dd><dt><a id="manual.bugs.dr415"></a><span class="term"><a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#415" target="_top">415</a>:
<span class="emphasis"><em>Behavior of std::ws</em></span>
</span></dt><dd><p>Change it to be an unformatted input function
(i.e. construct a sentry and catch exceptions).
</p></dd><dt><span class="term"><a class="link" href="../ext/lwg-closed.html#431" target="_top">431</a>:
<span class="emphasis"><em>Swapping containers with unequal allocators</em></span>
</span></dt><dd><p>Implement Option 3, as per N1599.

7
libstdc++-v3/doc/xml/manual/intro.xml
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@ -634,6 +634,13 @@ requirements of the license of GCC.
<listitem><para>Have <code>open</code> clear the error flags.
</para></listitem></varlistentry>
<varlistentry xml:id="manual.bugs.dr415"><term><link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="&DR;#415">415</link>:
<emphasis>Behavior of std::ws</emphasis>
</term>
<listitem><para>Change it to be an unformatted input function
(i.e. construct a sentry and catch exceptions).
</para></listitem></varlistentry>
<varlistentry><term><link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="../ext/lwg-closed.html#431">431</link>:
<emphasis>Swapping containers with unequal allocators</emphasis>
</term>

46
libstdc++-v3/include/bits/istream.tcc
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@ -1057,17 +1057,43 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
typedef typename __istream_type::int_type __int_type;
typedef ctype<_CharT> __ctype_type;
const __ctype_type& __ct = use_facet<__ctype_type>(__in.getloc());
const __int_type __eof = _Traits::eof();
__streambuf_type* __sb = __in.rdbuf();
__int_type __c = __sb->sgetc();
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 451. behavior of std::ws
typename __istream_type::sentry __cerb(__in, true);
if (__cerb)
{
ios_base::iostate __err = ios_base::goodbit;
__try
{
const __ctype_type& __ct = use_facet<__ctype_type>(__in.getloc());
const __int_type __eof = _Traits::eof();
__streambuf_type* __sb = __in.rdbuf();
__int_type __c = __sb->sgetc();
while (!_Traits::eq_int_type(__c, __eof)
&& __ct.is(ctype_base::space, _Traits::to_char_type(__c)))
__c = __sb->snextc();
if (_Traits::eq_int_type(__c, __eof))
__in.setstate(ios_base::eofbit);
while (true)
{
if (_Traits::eq_int_type(__c, __eof))
{
__err = ios_base::eofbit;
break;
}
if (!__ct.is(ctype_base::space, _Traits::to_char_type(__c)))
break;
__c = __sb->snextc();
}
}
__catch (const __cxxabiv1::__forced_unwind&)
{
__in._M_setstate(ios_base::badbit);
__throw_exception_again;
}
__catch (...)
{
__in._M_setstate(ios_base::badbit);
}
if (__err)
__in.setstate(__err);
}
return __in;
}

77
libstdc++-v3/testsuite/27_io/basic_istream/ws/char/lwg415.cc Normal file
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@ -0,0 +1,77 @@
#include <istream>
// C++11 27.7.2.4 Standard basic_istream manipulators [istream.manip]
//
// LWG 415. behavior of std::ws
// std::ws is an unformatted input function.
#include <istream>
#include <testsuite_hooks.h>
#include <testsuite_io.h>
void
test01()
{
std::istream is(0);
VERIFY( is.rdstate() == std::ios_base::badbit );
is >> std::ws; // sentry should set failbit
VERIFY( is.rdstate() & std::ios_base::failbit );
}
void
test02()
{
__gnu_test::sync_streambuf buf;
std::istream is(&buf);
__gnu_test::sync_streambuf buf_tie;
std::ostream os_tie(&buf_tie);
// A sentry should be constructed so is.tie()->flush() should be called.
// The standard allows the flush to be deferred because the put area of
// is_tie is empty, but libstdc++ doesn't defer it.
is.tie(&os_tie);
is >> std::ws;
VERIFY( is.eof() );
VERIFY( !is.fail() );
VERIFY( ! buf.sync_called() );
VERIFY( buf_tie.sync_called() );
}
void
test03()
{
__gnu_test::fail_streambuf buf;
std::istream is(&buf);
char c;
is >> c >> std::ws;
VERIFY( is.rdstate() == std::ios_base::badbit );
is.clear();
is.exceptions(std::ios_base::badbit);
try
{
is >> std::ws;
VERIFY( false );
}
catch (const __gnu_test::underflow_error&)
{
VERIFY( is.rdstate() == std::ios_base::badbit );
}
catch (...)
{
VERIFY( false );
}
}
int main()
{
test01();
test02();
test03();
}

77
libstdc++-v3/testsuite/27_io/basic_istream/ws/wchar_t/lwg415.cc Normal file
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@ -0,0 +1,77 @@
#include <istream>
// C++11 27.7.2.4 Standard basic_istream manipulators [istream.manip]
//
// LWG 415. behavior of std::ws
// std::ws is an unformatted input function.
#include <istream>
#include <testsuite_hooks.h>
#include <testsuite_io.h>
void
test01()
{
std::wistream is(0);
VERIFY( is.rdstate() == std::ios_base::badbit );
is >> std::ws; // sentry should set failbit
VERIFY( is.rdstate() & std::ios_base::failbit );
}
void
test02()
{
__gnu_test::sync_wstreambuf buf;
std::wistream is(&buf);
__gnu_test::sync_wstreambuf buf_tie;
std::wostream os_tie(&buf_tie);
// A sentry should be constructed so is.tie()->flush() should be called.
// The standard allows the flush to be deferred because the put area of
// is_tie is empty, but libstdc++ doesn't defer it.
is.tie(&os_tie);
is >> std::ws;
VERIFY( is.eof() );
VERIFY( !is.fail() );
VERIFY( ! buf.sync_called() );
VERIFY( buf_tie.sync_called() );
}
void
test03()
{
__gnu_test::fail_wstreambuf buf;
std::wistream is(&buf);
wchar_t c;
is >> c >> std::ws;
VERIFY( is.rdstate() == std::ios_base::badbit );
is.clear();
is.exceptions(std::ios_base::badbit);
try
{
is >> std::ws;
VERIFY( false );
}
catch (const __gnu_test::underflow_error&)
{
VERIFY( is.rdstate() == std::ios_base::badbit );
}
catch (...)
{
VERIFY( false );
}
}
int main()
{
test01();
test02();
test03();
}