Fails to build with GCC 6: call overloaded is ambiguous

[sebastic]

As reported by Martin Michlmayr in Debian Bug #811999:

This package fails to build with GCC 6. GCC 6 has not been released yet, but it's expected that GCC 6 will become the default compiler for stretch.

Note that only the first error is reported; there might be more. You can find a snapshot of GCC 6 in experimental. To build with GCC 6, you can set CC=gcc-6 CXX=g++-6 explicitly.

You may be able to find out more about this issue at https://gcc.gnu.org/gcc-6/changes.html

sbuild (Debian sbuild) 0.67.0 (26 Dec 2015) on dl580gen9-02.hlinux
...
==========================
c++ -I../include -I. -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Wall -Wextra -Wredundant-decls -Wdisabled-optimization -pedantic -Wctor-dtor-privacy -Wnon-virtual-dtor -Woverloaded-virtual -Wsign-promo -Wno-long-long -o tests test_main.o test_utils.o t/osmfile/test_read_and_write.cpp -I/usr/include -I/usr/include/gdal -L/usr/lib/x86_64-linux-gnu -lgeos-3.5.0 -L/usr/lib -lgdal -lboost_regex -lboost_iostreams -lboost_filesystem -lboost_system -DBOOST_TEST_DYN_LINK -Wl,-z,relro -lboost_unit_test_framework
--------------------------
t/osmfile/test_read_and_write.cpp: In member function 'void OSMFile_Output::write_to_xml_output_file::test_method()':
t/osmfile/test_read_and_write.cpp:65:48: error: call of overloaded 'basic_ifstream(TempFileFixture&, const openmode&)' is ambiguous
     std::ifstream in(test_osm, std::ios::binary);
                                                ^

In file included from t/osmfile/test_read_and_write.cpp:7:0:
/usr/include/c++/6/fstream:511:7: note: candidate: std::basic_ifstream<_CharT, _Traits>::basic_ifstream(const string&, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits<char>; std::__cxx11::string = std::__cxx11::basic_string<char>; std::ios_base::openmode = std::_Ios_Openmode]
       basic_ifstream(const std::string& __s,
       ^~~~~~~~~~~~~~

/usr/include/c++/6/fstream:495:7: note: candidate: std::basic_ifstream<_CharT, _Traits>::basic_ifstream(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits<char>; std::ios_base::openmode = std::_Ios_Openmode]
       basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
       ^~~~~~~~~~~~~~

t/osmfile/test_read_and_write.cpp: In member function 'void OSMFile_Output::write_to_xml_gz_output_file::test_method()':
t/osmfile/test_read_and_write.cpp:82:58: error: call of overloaded 'basic_ifstream(TempFileFixture&, const openmode&)' is ambiguous
     std::ifstream inputfile(test_osm_gz, std::ios::binary);
                                                          ^

In file included from t/osmfile/test_read_and_write.cpp:7:0:
/usr/include/c++/6/fstream:511:7: note: candidate: std::basic_ifstream<_CharT, _Traits>::basic_ifstream(const string&, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits<char>; std::__cxx11::string = std::__cxx11::basic_string<char>; std::ios_base::openmode = std::_Ios_Openmode]
       basic_ifstream(const std::string& __s,
       ^~~~~~~~~~~~~~

/usr/include/c++/6/fstream:495:7: note: candidate: std::basic_ifstream<_CharT, _Traits>::basic_ifstream(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits<char>; std::ios_base::openmode = std::_Ios_Openmode]
       basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
       ^~~~~~~~~~~~~~

t/osmfile/test_read_and_write.cpp: In member function 'void OSMFile_Output::write_to_xml_bz2_output_file::test_method()':
t/osmfile/test_read_and_write.cpp:102:59: error: call of overloaded 'basic_ifstream(TempFileFixture&, const openmode&)' is ambiguous
     std::ifstream inputfile(test_osm_bz2, std::ios::binary);

[joto]

The reason for the problem seems to be that GCC 6 compiles with --std=c++14 by default. I have fixed this now, but be aware that Osmium is not really supported any more. Everybody should switch to the new version libosmium.

[sebastic]

Thanks for the fix, I'll include the changes from b30afd3 in the Debian package.

I'd like to keep the old osmium package in Debian at least for the duration of the stretch stable release, to allow users to switch to libosmium (introduced in stretch) during that time. The early adopters can already use libosmium from jessie-backports.

I'll add a NEWS.Debian entry to document the deprecation in stretch and the suggested move to libosmium.