https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127006
Bug ID: 127006
Summary: ospanstream forces istream on ctor
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: Darrell.Wright at gmail dot com
Target Milestone: ---
The current implementation of ospanstreams ctor is using ios_base::in instead
of ios_base::out
https://eel.is/c++draft/span.streams#ospanstream.cons-1
https://github.com/gcc-mirror/gcc/blob/f1933b5ba13bb2abd1329cfb1ba9501c90f4c516/libstdc%2B%2B-v3/include/std/spanstream#L346
// [ospanstream.ctor], constructors
explicit
basic_ospanstream(std::span<_CharT> __s,
ios_base::openmode __which = ios_base::out)
: __ostream_type(std::__addressof(_M_sb)),
_M_sb(__s, __which | ios_base::in)
{ }
This makes code like
std::ospanstream stream {std::span(buffer), std::ios_base::binary};
fail to be writable
