[libcxx] r291961 - Add _LIBCPP_DIAGNOSE_WARNING and _LIBCPP_DIAGNOSE_ERROR macros.

George Burgess via cfe-commits cfe-commits at lists.llvm.org
Mon Jan 23 15:06:57 PST 2017


I like the idea of tagging diagnose_ifs with tags, though I wonder how this
could be made applicable to code outside of libcxx. Specifically, if I
import some big library that uses diagnose_if, then I'd still need to use
`-Wno-user-defined-warnings` if said lib had a single diagnose_if that I
didn't want to fix immediately.

My thought is that we may be able to tag these IDs with namespaces, and we
can match against those in the -Wno-user-defined-warnings=whatever.

For example:

namespace std {
  void foo(int i) __attribute__((diagnose_if(i, "oh no", "warning",
"foo_tag")));
  void bar(int i) __attribute__((diagnose_if(i, "oh no", "warning",
"bar_tag")));
}

-Wno-user-defined-warnings='std::' // all diagnose_ifs in std:: are disabled
-Wno-user-defined-warnings='std::foo_tag' // std::bar can warn
-Wno-user-defined-warnings='std::foo_tag,std::bar_tag' // neither std::foo
nor std::bar warn

If not this, then I'd like to at least consider some kind of wildcarding
thing in the warning flag, since libraries will likely roll their own
tag-namespaces anyway to avoid things like:

namespace boost {
  void foo(int i) __attribute__((diagnose_if(i, "oh no", "warning",
"foo")));
}
namespace internal_lib {
  void foo(int i) __attribute__((diagnose_if(i, "oh no", "warning",
"foo")));
}

-Wno-user-defined-warnings='foo' // disables boost::foo and
internal_lib::foo's warnings.

To be clear, I'm imagining the wildcards would look something like

#define _LIBCXX_TAG "libcxx_warning_"
namespace std {
  void foo(int i) __attribute__((diagnose_if(i, "oh no", "warning",
_LIBCXX_TAG "foo_tag")));
  void bar(int i) __attribute__((diagnose_if(i, "oh no", "warning",
_LIBCXX_TAG "bar_tag")));
}

-Wno-user-defined-warnings='libcxx_warning*' // std::foo and std::bar
warnings are disabled
-Wno-user-defined-warnings='libcxx_warning_foo_tag' // std::bar can warn
-Wno-user-defined-warnings='libcxx_warning_foo_tag,libcxx_warning_bar_tag'
// neither std::foo nor std::bar warn

...Personally, I'm leaning toward the implicit namespacing, since it's
impossible to forget (e.g. a library that doesn't use tags can be disabled
with 'lib_namespace::', instead of having to disable all user-defined
warnings), but I'd be content with either.

On Mon, Jan 23, 2017 at 2:11 PM, Eric Fiselier via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> My dream, and something I would like to work towards is supporting
> something like this:
>
>
On Mon, Jan 23, 2017 at 2:11 PM, Eric Fiselier <eric at efcs.ca> wrote:

> My dream, and something I would like to work towards is supporting
> something like this:
>
> > [[clang::libcxx_diagnose_if(cond, "message", "warning", /* warning-id*/
> "non-const-functor")]]
> >
> > -Wno-libcxx-warnings=non-const-functor
>
> This way libc++ warnings get treated differently from all other users of
> diagnose_if, and can be enabled
> and disabled separately.
>
> @George does this sound like a reasonable goal? If so I'm happy to start
> working on this.
>
> /Eric
>
>
> On Mon, Jan 23, 2017 at 11:46 AM, George Burgess <gbiv at google.com> wrote:
>
>> The only plan that we have at the moment is basically for a
>> -Wno-user-defined-warnings-in-system-headers type of flag. I agree that
>> it would be nice if we could be more granular than this, so I'll think
>> about what we can do.
>>
>> On Mon, Jan 23, 2017 at 8:36 AM, Nico Weber <thakis at chromium.org> wrote:
>>
>>> This happens to fire in practice in protobuf. It's probably a true
>>> positive and it's cool that this warning found it, but it means we have to
>>> disable Wuser-defined-warnings for a bit -- which then disables all of
>>> these user-defined warnings. Right now there aren't any others, but it
>>> feels like we'd want to have the ability to turn individual user-defined
>>> warnings on or off instead of just having a single toggle for all of them.
>>> Are there plans for something like that?
>>>
>>> On Fri, Jan 13, 2017 at 5:02 PM, Eric Fiselier via cfe-commits <
>>> cfe-commits at lists.llvm.org> wrote:
>>>
>>>> Author: ericwf
>>>> Date: Fri Jan 13 16:02:08 2017
>>>> New Revision: 291961
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=291961&view=rev
>>>> Log:
>>>> Add _LIBCPP_DIAGNOSE_WARNING and _LIBCPP_DIAGNOSE_ERROR macros.
>>>>
>>>> Clang recently added a `diagnose_if(cond, msg, type)` attribute
>>>> which can be used to generate diagnostics when `cond` is a constant
>>>> expression that evaluates to true. Otherwise no attribute has no
>>>> effect.
>>>>
>>>> This patch adds _LIBCPP_DIAGNOSE_ERROR/WARNING macros which
>>>> use this new attribute. Additionally this patch implements
>>>> a diagnostic message when a non-const-callable comparator is
>>>> given to a container.
>>>>
>>>> Note: For now the warning version of the diagnostic is useless
>>>> within libc++ since warning diagnostics are suppressed by the
>>>> system header pragma. I'm going to work on fixing this.
>>>>
>>>> Added:
>>>>     libcxx/trunk/test/libcxx/containers/associative/non_const_co
>>>> mparator.fail.cpp
>>>> Modified:
>>>>     libcxx/trunk/docs/UsingLibcxx.rst
>>>>     libcxx/trunk/include/__config
>>>>     libcxx/trunk/include/__tree
>>>>     libcxx/trunk/include/map
>>>>     libcxx/trunk/include/type_traits
>>>>     libcxx/trunk/test/libcxx/compiler.py
>>>>     libcxx/trunk/test/libcxx/test/config.py
>>>>     libcxx/trunk/test/libcxx/test/format.py
>>>>     libcxx/trunk/test/libcxx/utilities/tuple/tuple.tuple/diagnos
>>>> e_reference_binding.fail.cpp
>>>>
>>>> Modified: libcxx/trunk/docs/UsingLibcxx.rst
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/docs/UsingL
>>>> ibcxx.rst?rev=291961&r1=291960&r2=291961&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/docs/UsingLibcxx.rst (original)
>>>> +++ libcxx/trunk/docs/UsingLibcxx.rst Fri Jan 13 16:02:08 2017
>>>> @@ -173,3 +173,10 @@ thread safety annotations.
>>>>        return Tup{"hello world", 42}; // explicit constructor called.
>>>> OK.
>>>>      }
>>>>
>>>> +**_LIBCPP_DISABLE_ADDITIONAL_DIAGNOSTICS**:
>>>> +  This macro disables the additional diagnostics generated by libc++
>>>> using the
>>>> +  `diagnose_if` attribute. These additional diagnostics include checks
>>>> for:
>>>> +
>>>> +    * Giving `set`, `map`, `multiset`, `multimap` a comparator which
>>>> is not
>>>> +      const callable.
>>>> +
>>>>
>>>> Modified: libcxx/trunk/include/__config
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__c
>>>> onfig?rev=291961&r1=291960&r2=291961&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/include/__config (original)
>>>> +++ libcxx/trunk/include/__config Fri Jan 13 16:02:08 2017
>>>> @@ -1006,6 +1006,16 @@ _LIBCPP_FUNC_VIS extern "C" void __sanit
>>>>  #endif
>>>>  #endif
>>>>
>>>> +#if __has_attribute(diagnose_if) && !defined(_LIBCPP_DISABLE_ADDIT
>>>> IONAL_DIAGNOSTICS)
>>>> +# define _LIBCPP_DIAGNOSE_WARNING(...) \
>>>> +    __attribute__((__diagnose_if__(__VA_ARGS__, "warning")))
>>>> +# define _LIBCPP_DIAGNOSE_ERROR(...) \
>>>> +    __attribute__((__diagnose_if__(__VA_ARGS__, "error")))
>>>> +#else
>>>> +# define _LIBCPP_DIAGNOSE_WARNING(...)
>>>> +# define _LIBCPP_DIAGNOSE_ERROR(...)
>>>> +#endif
>>>> +
>>>>  #endif // __cplusplus
>>>>
>>>>  #endif // _LIBCPP_CONFIG
>>>>
>>>> Modified: libcxx/trunk/include/__tree
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__t
>>>> ree?rev=291961&r1=291960&r2=291961&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/include/__tree (original)
>>>> +++ libcxx/trunk/include/__tree Fri Jan 13 16:02:08 2017
>>>> @@ -41,6 +41,10 @@ template <class _Key, class _Value>
>>>>  struct __value_type;
>>>>  #endif
>>>>
>>>> +template <class _Key, class _CP, class _Compare,
>>>> +    bool = is_empty<_Compare>::value && !__libcpp_is_final<_Compare>::
>>>> value>
>>>> +class __map_value_compare;
>>>> +
>>>>  template <class _Allocator> class __map_node_destructor;
>>>>  template <class _TreeIterator> class _LIBCPP_TEMPLATE_VIS
>>>> __map_iterator;
>>>>  template <class _TreeIterator> class _LIBCPP_TEMPLATE_VIS
>>>> __map_const_iterator;
>>>> @@ -955,6 +959,30 @@ private:
>>>>
>>>>  };
>>>>
>>>> +#ifndef _LIBCPP_CXX03_LANG
>>>> +template <class _Tp, class _Compare, class _Allocator>
>>>> +struct __diagnose_tree_helper {
>>>> +  static constexpr bool __trigger_diagnostics()
>>>> +      _LIBCPP_DIAGNOSE_WARNING(!__is_const_comparable<_Compare,
>>>> _Tp>::value,
>>>> +            "the specified comparator type does not provide a const
>>>> call operator")
>>>> +  { return true; }
>>>> +};
>>>> +
>>>> +template <class _Key, class _Value, class _KeyComp, class _Alloc>
>>>> +struct __diagnose_tree_helper<
>>>> +    __value_type<_Key, _Value>,
>>>> +    __map_value_compare<_Key, __value_type<_Key, _Value>, _KeyComp>,
>>>> +    _Alloc
>>>> +>
>>>> +{
>>>> +  static constexpr bool __trigger_diagnostics()
>>>> +      _LIBCPP_DIAGNOSE_WARNING(!__is_const_comparable<_KeyComp,
>>>> _Key>::value,
>>>> +            "the specified comparator type does not provide a const
>>>> call operator")
>>>> +  { return true; }
>>>> +};
>>>> +
>>>> +#endif
>>>> +
>>>>  template <class _Tp, class _Compare, class _Allocator>
>>>>  class __tree
>>>>  {
>>>> @@ -1787,7 +1815,11 @@ __tree<_Tp, _Compare, _Allocator>::~__tr
>>>>  {
>>>>      static_assert((is_copy_constructible<value_compare>::value),
>>>>                   "Comparator must be copy-constructible.");
>>>> -    destroy(__root());
>>>> +#ifndef _LIBCPP_CXX03_LANG
>>>> +    static_assert((__diagnose_tree_helper<_Tp, _Compare, _Allocator>::
>>>> +                     __trigger_diagnostics()), "");
>>>> +#endif
>>>> +  destroy(__root());
>>>>  }
>>>>
>>>>  template <class _Tp, class _Compare, class _Allocator>
>>>>
>>>> Modified: libcxx/trunk/include/map
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/map
>>>> ?rev=291961&r1=291960&r2=291961&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/include/map (original)
>>>> +++ libcxx/trunk/include/map Fri Jan 13 16:02:08 2017
>>>> @@ -453,9 +453,7 @@ swap(multimap<Key, T, Compare, Allocator
>>>>
>>>>  _LIBCPP_BEGIN_NAMESPACE_STD
>>>>
>>>> -template <class _Key, class _CP, class _Compare,
>>>> -          bool = is_empty<_Compare>::value &&
>>>> !__libcpp_is_final<_Compare>::value
>>>> -         >
>>>> +template <class _Key, class _CP, class _Compare, bool _IsSmall>
>>>>  class __map_value_compare
>>>>      : private _Compare
>>>>  {
>>>>
>>>> Modified: libcxx/trunk/include/type_traits
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/typ
>>>> e_traits?rev=291961&r1=291960&r2=291961&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/include/type_traits (original)
>>>> +++ libcxx/trunk/include/type_traits Fri Jan 13 16:02:08 2017
>>>> @@ -4715,6 +4715,15 @@ struct __can_extract_map_key<_ValTy, _Ke
>>>>
>>>>  #endif
>>>>
>>>> +template <class _Comp, class _ValueType, class = void>
>>>> +struct __is_const_comparable : false_type {};
>>>> +
>>>> +template <class _Comp, class _ValueType>
>>>> +struct __is_const_comparable<_Comp, _ValueType, typename __void_t<
>>>> +    decltype(_VSTD::declval<_Comp const&>()(_VSTD::declval<_ValueType
>>>> const&>(),
>>>> +                                            _VSTD::declval<_ValueType
>>>> const&>()))
>>>> +  >::type> : true_type {};
>>>> +
>>>>  _LIBCPP_END_NAMESPACE_STD
>>>>
>>>>  #endif  // _LIBCPP_TYPE_TRAITS
>>>>
>>>> Modified: libcxx/trunk/test/libcxx/compiler.py
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/libcxx
>>>> /compiler.py?rev=291961&r1=291960&r2=291961&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/libcxx/compiler.py (original)
>>>> +++ libcxx/trunk/test/libcxx/compiler.py Fri Jan 13 16:02:08 2017
>>>> @@ -296,7 +296,7 @@ class CXXCompiler(object):
>>>>
>>>>      def addWarningFlagIfSupported(self, flag):
>>>>          if self.hasWarningFlag(flag):
>>>> -            assert flag not in self.warning_flags
>>>> -            self.warning_flags += [flag]
>>>> +            if flag not in self.warning_flags:
>>>> +                self.warning_flags += [flag]
>>>>              return True
>>>>          return False
>>>>
>>>> Added: libcxx/trunk/test/libcxx/containers/associative/non_const_co
>>>> mparator.fail.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/libcxx
>>>> /containers/associative/non_const_comparator.fail.cpp?rev=29
>>>> 1961&view=auto
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/libcxx/containers/associative/non_const_comparator.fail.cpp
>>>> (added)
>>>> +++ libcxx/trunk/test/libcxx/containers/associative/non_const_comparator.fail.cpp
>>>> Fri Jan 13 16:02:08 2017
>>>> @@ -0,0 +1,45 @@
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +//
>>>> +//                     The LLVM Compiler Infrastructure
>>>> +//
>>>> +// This file is dual licensed under the MIT and the University of
>>>> Illinois Open
>>>> +// Source Licenses. See LICENSE.TXT for details.
>>>> +//
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +
>>>> +// UNSUPPORTED: c++98, c++03
>>>> +// REQUIRES: diagnose-if-support, verify-support
>>>> +
>>>> +// Test that libc++ generates a warning diagnostic when the container
>>>> is
>>>> +// provided a non-const callable comparator.
>>>> +
>>>> +#include <set>
>>>> +#include <map>
>>>> +
>>>> +struct BadCompare {
>>>> +  template <class T, class U>
>>>> +  bool operator()(T const& t, U const& u) {
>>>> +    return t < u;
>>>> +  }
>>>> +};
>>>> +
>>>> +int main() {
>>>> +  static_assert(!std::__is_const_comparable<BadCompare, int>::value,
>>>> "");
>>>> +  // expected-warning at __tree:* 4 {{the specified comparator type does
>>>> not provide a const call operator}}
>>>> +  {
>>>> +    using C = std::set<int, BadCompare>;
>>>> +    C s;
>>>> +  }
>>>> +  {
>>>> +    using C = std::multiset<long, BadCompare>;
>>>> +    C s;
>>>> +  }
>>>> +  {
>>>> +    using C = std::map<int, int, BadCompare>;
>>>> +    C s;
>>>> +  }
>>>> +  {
>>>> +    using C = std::multimap<long, int, BadCompare>;
>>>> +    C s;
>>>> +  }
>>>> +}
>>>>
>>>> Modified: libcxx/trunk/test/libcxx/test/config.py
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/libcxx
>>>> /test/config.py?rev=291961&r1=291960&r2=291961&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/libcxx/test/config.py (original)
>>>> +++ libcxx/trunk/test/libcxx/test/config.py Fri Jan 13 16:02:08 2017
>>>> @@ -712,33 +712,35 @@ class Configuration(object):
>>>>                  ['c++11', 'c++14', 'c++1z'])) != 0
>>>>          enable_warnings = self.get_lit_bool('enable_warnings',
>>>>                                              default_enable_warnings)
>>>> -        if enable_warnings:
>>>> -            self.cxx.useWarnings(True)
>>>> -            self.cxx.warning_flags += [
>>>> -                '-D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER',
>>>> -                '-Wall', '-Wextra', '-Werror'
>>>> -            ]
>>>> -            self.cxx.addWarningFlagIfSupported('-Wshadow')
>>>> -            self.cxx.addWarningFlagIfSuppo
>>>> rted('-Wno-unused-command-line-argument')
>>>> -            self.cxx.addWarningFlagIfSupported('-Wno-attributes')
>>>> -            self.cxx.addWarningFlagIfSuppo
>>>> rted('-Wno-pessimizing-move')
>>>> -            self.cxx.addWarningFlagIfSuppo
>>>> rted('-Wno-c++11-extensions')
>>>> -            self.cxx.addWarningFlagIfSuppo
>>>> rted('-Wno-user-defined-literals')
>>>> -            # These warnings should be enabled in order to support the
>>>> MSVC
>>>> -            # team using the test suite; They enable the warnings
>>>> below and
>>>> -            # expect the test suite to be clean.
>>>> -            self.cxx.addWarningFlagIfSupported('-Wsign-compare')
>>>> -            self.cxx.addWarningFlagIfSupported('-Wunused-variable')
>>>> -            self.cxx.addWarningFlagIfSupported('-Wunused-parameter')
>>>> -            self.cxx.addWarningFlagIfSupported('-Wunreachable-code')
>>>> -            # FIXME: Enable the two warnings below.
>>>> -            self.cxx.addWarningFlagIfSupported('-Wno-conversion')
>>>> +        self.cxx.useWarnings(enable_warnings)
>>>> +        self.cxx.warning_flags += [
>>>> +            '-D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER',
>>>> +            '-Wall', '-Wextra', '-Werror'
>>>> +        ]
>>>> +        if self.cxx.hasWarningFlag('-Wuser-defined-warnings'):
>>>> +            self.cxx.warning_flags += ['-Wuser-defined-warnings']
>>>> +            self.config.available_features.add('diagnose-if-support')
>>>> +        self.cxx.addWarningFlagIfSupported('-Wshadow')
>>>> +        self.cxx.addWarningFlagIfSupported('-Wno-unused-command-line
>>>> -argument')
>>>> +        self.cxx.addWarningFlagIfSupported('-Wno-attributes')
>>>> +        self.cxx.addWarningFlagIfSupported('-Wno-pessimizing-move')
>>>> +        self.cxx.addWarningFlagIfSupported('-Wno-c++11-extensions')
>>>> +        self.cxx.addWarningFlagIfSupported('-Wno-user-defined-litera
>>>> ls')
>>>> +        # These warnings should be enabled in order to support the MSVC
>>>> +        # team using the test suite; They enable the warnings below and
>>>> +        # expect the test suite to be clean.
>>>> +        self.cxx.addWarningFlagIfSupported('-Wsign-compare')
>>>> +        self.cxx.addWarningFlagIfSupported('-Wunused-variable')
>>>> +        self.cxx.addWarningFlagIfSupported('-Wunused-parameter')
>>>> +        self.cxx.addWarningFlagIfSupported('-Wunreachable-code')
>>>> +        # FIXME: Enable the two warnings below.
>>>> +        self.cxx.addWarningFlagIfSupported('-Wno-conversion')
>>>> +        self.cxx.addWarningFlagIfSupported('-Wno-unused-local-typede
>>>> f')
>>>> +        std = self.get_lit_conf('std', None)
>>>> +        if std in ['c++98', 'c++03']:
>>>> +            # The '#define static_assert' provided by libc++ in C++03
>>>> mode
>>>> +            # causes an unused local typedef whenever it is used.
>>>>              self.cxx.addWarningFlagIfSupp
>>>> orted('-Wno-unused-local-typedef')
>>>> -            std = self.get_lit_conf('std', None)
>>>> -            if std in ['c++98', 'c++03']:
>>>> -                # The '#define static_assert' provided by libc++ in
>>>> C++03 mode
>>>> -                # causes an unused local typedef whenever it is used.
>>>> -                self.cxx.addWarningFlagIfSuppo
>>>> rted('-Wno-unused-local-typedef')
>>>>
>>>>      def configure_sanitizer(self):
>>>>          san = self.get_lit_conf('use_sanitizer', '').strip()
>>>>
>>>> Modified: libcxx/trunk/test/libcxx/test/format.py
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/libcxx
>>>> /test/format.py?rev=291961&r1=291960&r2=291961&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/libcxx/test/format.py (original)
>>>> +++ libcxx/trunk/test/libcxx/test/format.py Fri Jan 13 16:02:08 2017
>>>> @@ -223,6 +223,10 @@ class LibcxxTestFormat(object):
>>>>              test_cxx.flags += ['-fsyntax-only']
>>>>          if use_verify:
>>>>              test_cxx.useVerify()
>>>> +            test_cxx.useWarnings()
>>>> +            if '-Wuser-defined-warnings' in test_cxx.warning_flags:
>>>> +                test_cxx.warning_flags +=
>>>> ['-Wno-error=user-defined-warnings']
>>>> +
>>>>          cmd, out, err, rc = test_cxx.compile(source_path,
>>>> out=os.devnull)
>>>>          expected_rc = 0 if use_verify else 1
>>>>          if rc == expected_rc:
>>>>
>>>> Modified: libcxx/trunk/test/libcxx/utilities/tuple/tuple.tuple/diagnos
>>>> e_reference_binding.fail.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/libcxx
>>>> /utilities/tuple/tuple.tuple/diagnose_reference_binding.fail
>>>> .cpp?rev=291961&r1=291960&r2=291961&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/libcxx/utilities/tuple/tuple.tuple/diagnose_reference_binding.fail.cpp
>>>> (original)
>>>> +++ libcxx/trunk/test/libcxx/utilities/tuple/tuple.tuple/diagnose_reference_binding.fail.cpp
>>>> Fri Jan 13 16:02:08 2017
>>>> @@ -30,4 +30,11 @@ int main() {
>>>>      // bind rvalue to constructed non-rvalue
>>>>      std::tuple<std::string &&> t2("hello"); // expected-note
>>>> {{requested here}}
>>>>      std::tuple<std::string &&> t3(std::allocator_arg, alloc, "hello");
>>>> // expected-note {{requested here}}
>>>> +
>>>> +    // FIXME: The below warnings may get emitted as an error, a
>>>> warning, or not emitted at all
>>>> +    // depending on the flags used to compile this test.
>>>> +  {
>>>> +    // expected-warning at tuple:* 0+ {{binding reference member 'value'
>>>> to a temporary value}}
>>>> +    // expected-error at tuple:* 0+ {{binding reference member 'value'
>>>> to a temporary value}}
>>>> +  }
>>>>  }
>>>>
>>>>
>>>> _______________________________________________
>>>> cfe-commits mailing list
>>>> cfe-commits at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>>>>
>>>
>>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20170123/6af45024/attachment-0001.html>


More information about the cfe-commits mailing list