ubuntu-bugcontrol team mailing list archive

[Launchpad Bug Tracker <1610168@xxxxxxxxxxxxxxxxxx>]

You have been subscribed to a public bug by Giuseppe D'Angelo (dangelo):

This is mirroring Debian bug #808086 https://bugs.debian.org/cgi-
bin/bugreport.cgi?bug=808086

Compiling any source file that includes <string> with clang 3.8 and
-std=c++11 -stdlib=libc++ results in a compile error.

While this is a minor bug in Debian (as it doesn't ship 3.8 yet), xenial
does, and that's a major problem as it makes libc++ useless.

clang: warning: argument unused during compilation: '-stdlib=libc++'
In file included from test.cpp:1:
In file included from /usr/include/c++/v1/iostream:38:
In file included from /usr/include/c++/v1/ios:216:
In file included from /usr/include/c++/v1/__locale:15:
/usr/include/c++/v1/string:1938:44: error: 'basic_string<_CharT, _Traits, _Allocator>' is missing exception specification 'noexcept(is_nothrow_copy_constructible<allocator_type>::value)'
basic_string<_CharT, _Traits, _Allocator>::basic_string(const allocator_type& __a)
                                           ^
/usr/include/c++/v1/string:1326:76: note: previous declaration is here
    __attribute__ ((__visibility__("hidden"), __always_inline__)) explicit basic_string(const allocator_type& __a)
                                                                           ^
1 error generated.

--

Update (30 Aug 2017): as per
https://wiki.ubuntu.com/StableReleaseUpdates :

[Impact]

This bug makes it impossible to compile any C++11 source file that
includes <string> with clang 3.8 using libc++. Any non-trivial C++11
codebase is affected, making the whole libc++ package useless.

[Test Case]

See above. Create a C++ file that simply contains #include <string> and
compile it with clang++ -std=c++11 -stdlib=libc++ file.cpp.

[Regression Potential]

The current <string> header simply does not work with clang-3.8 under
any condition, so there is no regression potential.

The regression potential for GCC is also extremely limited: no package
whatsoever uses GCC in combination with libc++, and the fact that GCC
5.4 -- currently in Xenial -- does not detect the error that Clang
detects is just showing that GCC is bugged in this regard.

[Other Info]

The patch/workaround fixes the problem. See also the discussion at the
linked Debian bug report as well as https://stackoverflow.com/q/37096062

** Affects: libc++ (Ubuntu)
     Importance: Undecided
         Status: Confirmed


** Tags: patch
-- 
error: 'basic_string<_CharT, _Traits, _Allocator>' is missing exception specification
https://bugs.launchpad.net/bugs/1610168
You received this bug notification because you are a member of Ubuntu Bug Control, which is subscribed to the bug report.