This implements the resolution of LWG 1203 so that the constraints for
rvalue stream insertion/extraction are simpler, and the return type is
the original rvalue stream type not its base class.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/std/istream (operator>>(Istream&&, x&)): Simplify, as
per LWG 1203.
* include/std/ostream (operator<<(Ostream&&, const x&)):
Likewise.
* testsuite/27_io/basic_istream/extractors_character/char/lwg2499_neg.cc:
Adjust dg-error pattern.
* testsuite/27_io/basic_istream/extractors_character/wchar_t/lwg2499_neg.cc:
Likewise.
* testsuite/27_io/basic_istream/extractors_other/char/4.cc: Define
is_extractable trait to replace std::__is_extractable. Make it
work with rvalue streams as well as lvalues, to replace f() and
g() helper functions.
* testsuite/27_io/basic_istream/extractors_other/wchar_t/4.cc:
Likewise.
* testsuite/27_io/basic_ostream/inserters_other/char/6.cc:
Define is_insertable trait to replace std::__is_insertable. Make
it work with rvalue streams as well as lvalues, to replace f()
and g() helper functions.
* testsuite/27_io/basic_ostream/inserters_other/wchar_t/6.cc:
Likewise.
* testsuite/27_io/filesystem/path/io/dr2989.cc: Prune additional
errors from new constraints.
* testsuite/27_io/rvalue_streams-2.cc: Remove PR 80675 checks,
which are no longer expected to compile.
* testsuite/27_io/rvalue_streams.cc: Adjust existing test.
Verify LWG 1203 changes.
* call.c (convert_class_to_reference): Binding an lvalue to an
rvalue reference is bad. If the user-defined conversion is bad,
set bad_p before merging conversions.
(maybe_handle_ref_bind): Don't push down bad_p.
(reference_binding): Binding an lvalue to an rvalue reference is bad.
(convert_like_real): Give a helpful error about binding lvalue
to rvalue reference.
(reference_related_p): No longer static.
* typeck.c (build_typed_address): New.
(build_static_cast_1): Add static_cast from lvalue to &&.
* cp-tree.h: Adjust.
* include/bits/move.h (forward): Implement as in N2835.
(move): Implement as in N2831.
* include/std/istream (rvalue stream operator>>): New.
* include/std/ostream (rvalue stream operator<<): New.
Co-Authored-By: Douglas Gregor <doug.gregor@gmail.com>
From-SVN: r150327
