https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86138
--- Comment #13 from Christian Franke <franke at computer dot org> ---
This patch prevents duplicate _S_empty_rep_storage[] even on Cygwin (char only,
wchar_t missing). Testcase works as expected then:
--- basic_string.tcc.orig 2018-05-03 06:22:46.000000000 +0200
+++ basic_string.tcc 2018-06-21 13:00:03.370070700 +0200
@@ -1597,7 +1597,8 @@
// Inhibit implicit instantiations for required instantiations,
// which are defined via explicit instantiations elsewhere.
-#if _GLIBCXX_EXTERN_TEMPLATE > 0 && __cplusplus <= 201402L
+#if _GLIBCXX_EXTERN_TEMPLATE > 0
+#if __cplusplus <= 201402L
extern template class basic_string<char>;
extern template
basic_istream<char>&
@@ -1627,6 +1628,12 @@
basic_istream<wchar_t>&
getline(basic_istream<wchar_t>&, wstring&);
#endif
+
+#else
+ extern template
+ basic_string<char>::size_type
+ basic_string<char>::_Rep::_S_empty_rep_storage[];
+#endif
#endif
On Linux and other platforms using ELF the problem does not occur because
template static data members use the GNU extension ".type ...
@gnu_unique_object" (nm command prints 'u').
Are there possibly other platforms affected?
For example:
- ELF based platforms were dynamic linker does not support this GNU extension,
or
- non ELF based platforms without a similar feature.
