[Bug libstdc++/66030] [5.1.0] std::codecvt_byname missing from libstdc++ DLL

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66030

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Does this work?

--- a/libstdc++-v3/config/abi/pre/gnu.ver
+++ b/libstdc++-v3/config/abi/pre/gnu.ver
@@ -542,6 +542,9 @@ GLIBCXX_3.4 {
     # std::codecvt_byname
     _ZNSt14codecvt_bynameI[cw]c11__mbstate_tEC[12]EPKc[jmy];
     _ZNSt14codecvt_bynameI[cw]c11__mbstate_tED*;
+#if defined (_WIN32) && !defined (__CYGWIN__)
+    _ZNSt14codecvt_bynameI[cw]ciE[CD]*;
+#endif

     # std::collate
     _ZNSt7collateI[cw]*;

This won't affect any targets which use versioned symbols.