Tested x86_64-linux. Pushed to trunk.
-- >8 --
These are all pure functions and MSVC also marks all of these as
nodiscard except for std::basic_ios::tie() const, but that's been
confirmed as an accidental omission.
libstdc++-v3/ChangeLog:
* include/bits/basic_ios.h (basic_ios::operator bool()):
Add [[nodiscard]] attribute.
(basic_ios::operator!(), basic_ios::rdstate())
(basic_ios::good(), basic_ios::eof(), basic_ios::fail())
(basic_ios::bad(), basic_ios::exceptions(), basic_ios::tie())
(basic_ios::rdbuf(), basic_ios::fill()): Likewise.
* include/bits/ios_base.h (ios_base::flags()): Likewise.
(ios_base::precision(), ios_base::width(), ios_base::getloc()):
Likewise.
* include/std/fstream (basic_filebuf::is_open)
(basic_ifstream::rdbuf(), basic_ifstream::is_open)
(basic_ofstream::rdbuf(), basic_ofstream::is_open)
(basic_fstream::rdbuf(), basic_fstream::is_open): Likewise.
* include/std/spanstream (basic_spanbuf::span())
(basic_ispanstream::span(), basic_ispanstream::rdbuf())
(basic_ospanstream::span(), basic_ospanstream::rdbuf())
(basic_spanstream::span(), basic_spanstream::rdbuf()):
Likewise.
* include/std/sstream (basic_stringbuf::str())
(basic_istringstream::rdbuf(), basic_istringstream::str())
(basic_ostringstream::rdbuf(), basic_ostringstream::str())
(basic_stringstream::rdbuf(), basic_stringstream::str()):
Likewise.
* testsuite/27_io/basic_istream/extractors_arithmetic/char/01.cc:
Suppress -Wunused-result warnings.
* testsuite/27_io/basic_istream/extractors_arithmetic/wchar_t/01.cc:
Likewise.
---
libstdc++-v3/include/bits/basic_ios.h | 11 +++++++++++
libstdc++-v3/include/bits/ios_base.h | 4 ++++
libstdc++-v3/include/std/fstream | 10 ++++++++++
libstdc++-v3/include/std/spanstream | 7 +++++++
libstdc++-v3/include/std/sstream | 15 +++++++++++++++
.../extractors_arithmetic/char/01.cc | 4 ++--
.../extractors_arithmetic/wchar_t/01.cc | 4 ++--
7 files changed, 51 insertions(+), 4 deletions(-)
diff --git a/libstdc++-v3/include/bits/basic_ios.h
b/libstdc++-v3/include/bits/basic_ios.h
index a2d8060edd2..8954ad16d63 100644
--- a/libstdc++-v3/include/bits/basic_ios.h
+++ b/libstdc++-v3/include/bits/basic_ios.h
@@ -120,6 +120,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* <code>if (!a_stream) ...</code> and <code>while (a_stream) ...</code>
*/
#if __cplusplus >= 201103L
+ _GLIBCXX_NODISCARD
explicit operator bool() const
{ return !this->fail(); }
#else
@@ -127,6 +128,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ return this->fail() ? 0 : const_cast<basic_ios*>(this); }
#endif
+ _GLIBCXX_NODISCARD
bool
operator!() const
{ return this->fail(); }
@@ -139,6 +141,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* See std::ios_base::iostate for the possible bit values. Most
* users will call one of the interpreting wrappers, e.g., good().
*/
+ _GLIBCXX_NODISCARD
iostate
rdstate() const
{ return _M_streambuf_state; }
@@ -182,6 +185,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*
* A wrapper around rdstate.
*/
+ _GLIBCXX_NODISCARD
bool
good() const
{ return this->rdstate() == 0; }
@@ -192,6 +196,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*
* Note that other iostate flags may also be set.
*/
+ _GLIBCXX_NODISCARD
bool
eof() const
{ return (this->rdstate() & eofbit) != 0; }
@@ -203,6 +208,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* Checking the badbit in fail() is historical practice.
* Note that other iostate flags may also be set.
*/
+ _GLIBCXX_NODISCARD
bool
fail() const
{ return (this->rdstate() & (badbit | failbit)) != 0; }
@@ -213,6 +219,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*
* Note that other iostate flags may also be set.
*/
+ _GLIBCXX_NODISCARD
bool
bad() const
{ return (this->rdstate() & badbit) != 0; }
@@ -224,6 +231,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* This changes nothing in the stream. See the one-argument version
* of exceptions(iostate) for the meaning of the return value.
*/
+ _GLIBCXX_NODISCARD
iostate
exceptions() const
{ return _M_exception; }
@@ -297,6 +305,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* stream. When this stream performs any I/O, the tied stream is
* first flushed. For example, @c std::cin is tied to @c std::cout.
*/
+ _GLIBCXX_NODISCARD
basic_ostream<_CharT, _Traits>*
tie() const
{ return _M_tie; }
@@ -323,6 +332,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*
* This does not change the state of the stream.
*/
+ _GLIBCXX_NODISCARD
basic_streambuf<_CharT, _Traits>*
rdbuf() const
{ return _M_streambuf; }
@@ -372,6 +382,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*
* It defaults to a space (' ') in the current locale.
*/
+ _GLIBCXX_NODISCARD
char_type
fill() const
{
diff --git a/libstdc++-v3/include/bits/ios_base.h
b/libstdc++-v3/include/bits/ios_base.h
index a649448e298..1418b18830a 100644
--- a/libstdc++-v3/include/bits/ios_base.h
+++ b/libstdc++-v3/include/bits/ios_base.h
@@ -689,6 +689,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* @brief Access to format flags.
* @return The format control flags for both input and output.
*/
+ _GLIBCXX_NODISCARD
fmtflags
flags() const
{ return _M_flags; }
@@ -759,6 +760,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* Be careful if you try to give a definition of @a precision here; see
* DR 189.
*/
+ _GLIBCXX_NODISCARD
streamsize
precision() const
{ return _M_precision; }
@@ -782,6 +784,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*
* <em>Minimum field width</em> refers to the number of characters.
*/
+ _GLIBCXX_NODISCARD
streamsize
width() const
{ return _M_width; }
@@ -833,6 +836,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* returns @c loc. Otherwise, it returns a copy of @c std::locale(),
* the global C++ locale.
*/
+ _GLIBCXX_NODISCARD
locale
getloc() const
{ return _M_ios_locale; }
diff --git a/libstdc++-v3/include/std/fstream b/libstdc++-v3/include/std/fstream
index 665a17afee6..8f359404a48 100644
--- a/libstdc++-v3/include/std/fstream
+++ b/libstdc++-v3/include/std/fstream
@@ -273,6 +273,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @brief Returns true if the external file is open.
*/
+ _GLIBCXX_NODISCARD
bool
is_open() const throw()
{ return _M_file.is_open(); }
@@ -670,6 +671,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*
* This hides both signatures of std::basic_ios::rdbuf().
*/
+ _GLIBCXX_NODISCARD
__filebuf_type*
rdbuf() const
{ return const_cast<__filebuf_type*>(&_M_filebuf); }
@@ -678,12 +680,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* @brief Wrapper to test for an open file.
* @return @c rdbuf()->is_open()
*/
+ _GLIBCXX_NODISCARD
bool
is_open()
{ return _M_filebuf.is_open(); }
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 365. Lack of const-qualification in clause 27
+ _GLIBCXX_NODISCARD
bool
is_open() const
{ return _M_filebuf.is_open(); }
@@ -942,6 +946,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*
* This hides both signatures of std::basic_ios::rdbuf().
*/
+ _GLIBCXX_NODISCARD
__filebuf_type*
rdbuf() const
{ return const_cast<__filebuf_type*>(&_M_filebuf); }
@@ -950,12 +955,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* @brief Wrapper to test for an open file.
* @return @c rdbuf()->is_open()
*/
+ _GLIBCXX_NODISCARD
bool
is_open()
{ return _M_filebuf.is_open(); }
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 365. Lack of const-qualification in clause 27
+ _GLIBCXX_NODISCARD
bool
is_open() const
{ return _M_filebuf.is_open(); }
@@ -1207,6 +1214,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*
* This hides both signatures of std::basic_ios::rdbuf().
*/
+ _GLIBCXX_NODISCARD
__filebuf_type*
rdbuf() const
{ return const_cast<__filebuf_type*>(&_M_filebuf); }
@@ -1215,12 +1223,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* @brief Wrapper to test for an open file.
* @return @c rdbuf()->is_open()
*/
+ _GLIBCXX_NODISCARD
bool
is_open()
{ return _M_filebuf.is_open(); }
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 365. Lack of const-qualification in clause 27
+ _GLIBCXX_NODISCARD
bool
is_open() const
{ return _M_filebuf.is_open(); }
diff --git a/libstdc++-v3/include/std/spanstream
b/libstdc++-v3/include/std/spanstream
index b86bd613489..98ad3fa856a 100644
--- a/libstdc++-v3/include/std/spanstream
+++ b/libstdc++-v3/include/std/spanstream
@@ -110,6 +110,7 @@ template<typename _CharT, typename _Traits>
}
// [spanbuf.members], member functions
+ [[nodiscard]]
std::span<_CharT>
span() const noexcept
{
@@ -277,12 +278,14 @@ template<typename _CharT, typename _Traits>
}
// [ispanstream.members], member functions
+ [[nodiscard]]
basic_spanbuf<_CharT, _Traits>*
rdbuf() const noexcept
{
return const_cast<basic_spanbuf<_CharT,
_Traits>*>(std::__addressof(_M_sb));
}
+ [[nodiscard]]
std::span<const _CharT>
span() const noexcept
{ return _M_sb.span(); }
@@ -356,12 +359,14 @@ template<typename _CharT, typename _Traits>
}
// [ospanstream.members], member functions
+ [[nodiscard]]
basic_spanbuf<_CharT, _Traits>*
rdbuf() const noexcept
{
return const_cast<basic_spanbuf<_CharT,
_Traits>*>(std::__addressof(_M_sb));
}
+ [[nodiscard]]
std::span<_CharT>
span() const noexcept
{ return _M_sb.span(); }
@@ -424,12 +429,14 @@ template<typename _CharT, typename _Traits>
}
// [spanstream.members], members
+ [[nodiscard]]
basic_spanbuf<_CharT, _Traits>*
rdbuf() const noexcept
{
return const_cast<basic_spanbuf<_CharT,
_Traits>*>(std::__addressof(_M_sb));
}
+ [[nodiscard]]
std::span<_CharT>
span() const noexcept
{ return _M_sb.span(); }
diff --git a/libstdc++-v3/include/std/sstream b/libstdc++-v3/include/std/sstream
index fd24f655218..aaa89b2bed8 100644
--- a/libstdc++-v3/include/std/sstream
+++ b/libstdc++-v3/include/std/sstream
@@ -247,6 +247,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* character sequence is equal to the input sequence; otherwise, it
* is equal to the output sequence.</em> [27.7.1.2]/1
*/
+ _GLIBCXX_NODISCARD
__string_type
str() const _GLIBCXX_LVAL_REF_QUAL
{
@@ -262,6 +263,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
#if _GLIBCXX_USE_CXX11_ABI
#if __cpp_concepts
template<__allocator_like _SAlloc>
+ _GLIBCXX_NODISCARD
basic_string<_CharT, _Traits, _SAlloc>
str(const _SAlloc& __sa) const
{
@@ -270,6 +272,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
}
#endif
+ _GLIBCXX_NODISCARD
__string_type
str() &&
{
@@ -696,6 +699,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
*
* This hides both signatures of std::basic_ios::rdbuf().
*/
+ _GLIBCXX_NODISCARD
__stringbuf_type*
rdbuf() const
{ return const_cast<__stringbuf_type*>(&_M_stringbuf); }
@@ -704,6 +708,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @brief Copying out the string buffer.
* @return @c rdbuf()->str()
*/
+ _GLIBCXX_NODISCARD
__string_type
str() const _GLIBCXX_LVAL_REF_QUAL
{ return _M_stringbuf.str(); }
@@ -712,11 +717,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
#if _GLIBCXX_USE_CXX11_ABI
#if __cpp_concepts
template<__allocator_like _SAlloc>
+ _GLIBCXX_NODISCARD
basic_string<_CharT, _Traits, _SAlloc>
str(const _SAlloc& __sa) const
{ return _M_stringbuf.str(__sa); }
#endif
+ _GLIBCXX_NODISCARD
__string_type
str() &&
{ return std::move(_M_stringbuf).str(); }
@@ -920,6 +927,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
*
* This hides both signatures of std::basic_ios::rdbuf().
*/
+ _GLIBCXX_NODISCARD
__stringbuf_type*
rdbuf() const
{ return const_cast<__stringbuf_type*>(&_M_stringbuf); }
@@ -928,6 +936,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @brief Copying out the string buffer.
* @return @c rdbuf()->str()
*/
+ _GLIBCXX_NODISCARD
__string_type
str() const _GLIBCXX_LVAL_REF_QUAL
{ return _M_stringbuf.str(); }
@@ -936,11 +945,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
#if _GLIBCXX_USE_CXX11_ABI
#if __cpp_concepts
template<__allocator_like _SAlloc>
+ _GLIBCXX_NODISCARD
basic_string<_CharT, _Traits, _SAlloc>
str(const _SAlloc& __sa) const
{ return _M_stringbuf.str(__sa); }
#endif
+ _GLIBCXX_NODISCARD
__string_type
str() &&
{ return std::move(_M_stringbuf).str(); }
@@ -1142,6 +1153,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
*
* This hides both signatures of std::basic_ios::rdbuf().
*/
+ _GLIBCXX_NODISCARD
__stringbuf_type*
rdbuf() const
{ return const_cast<__stringbuf_type*>(&_M_stringbuf); }
@@ -1150,6 +1162,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @brief Copying out the string buffer.
* @return @c rdbuf()->str()
*/
+ _GLIBCXX_NODISCARD
__string_type
str() const _GLIBCXX_LVAL_REF_QUAL
{ return _M_stringbuf.str(); }
@@ -1158,11 +1171,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
#if _GLIBCXX_USE_CXX11_ABI
#if __cpp_concepts
template<__allocator_like _SAlloc>
+ _GLIBCXX_NODISCARD
basic_string<_CharT, _Traits, _SAlloc>
str(const _SAlloc& __sa) const
{ return _M_stringbuf.str(__sa); }
#endif
+ _GLIBCXX_NODISCARD
__string_type
str() &&
{ return std::move(_M_stringbuf).str(); }
diff --git
a/libstdc++-v3/testsuite/27_io/basic_istream/extractors_arithmetic/char/01.cc
b/libstdc++-v3/testsuite/27_io/basic_istream/extractors_arithmetic/char/01.cc
index 08cbd5fc902..1ebadd1913f 100644
---
a/libstdc++-v3/testsuite/27_io/basic_istream/extractors_arithmetic/char/01.cc
+++
b/libstdc++-v3/testsuite/27_io/basic_istream/extractors_arithmetic/char/01.cc
@@ -60,7 +60,7 @@ void test01() {
// process alphanumeric versions of bool values
is_02.setf(std::ios_base::boolalpha);
- is_02.flags();
+ (void) is_02.flags();
is_02 >> b1;
VERIFY( b1 == 1 );
is_02 >> b1;
@@ -68,7 +68,7 @@ void test01() {
// process numeric versions of of bool values
is_02.unsetf(std::ios_base::boolalpha);
- is_02.flags();
+ (void) is_02.flags();
is_02 >> b1;
VERIFY( b1 == 0 );
is_02 >> b1;
diff --git
a/libstdc++-v3/testsuite/27_io/basic_istream/extractors_arithmetic/wchar_t/01.cc
b/libstdc++-v3/testsuite/27_io/basic_istream/extractors_arithmetic/wchar_t/01.cc
index 2b70390fe2b..26db8c549f2 100644
---
a/libstdc++-v3/testsuite/27_io/basic_istream/extractors_arithmetic/wchar_t/01.cc
+++
b/libstdc++-v3/testsuite/27_io/basic_istream/extractors_arithmetic/wchar_t/01.cc
@@ -58,7 +58,7 @@ void test01() {
// process alphanumeric versions of bool values
is_02.setf(std::ios_base::boolalpha);
- is_02.flags();
+ (void) is_02.flags();
is_02 >> b1;
VERIFY( b1 == 1 );
is_02 >> b1;
@@ -66,7 +66,7 @@ void test01() {
// process numeric versions of of bool values
is_02.unsetf(std::ios_base::boolalpha);
- is_02.flags();
+ (void) is_02.flags();
is_02 >> b1;
VERIFY( b1 == 0 );
is_02 >> b1;
--
2.46.1
