ABI break in locale_ref ctor (11.0.0 -> 11.1.1)

[jengelh]

Commit ff92223 changed:

-  template <typename Locale> explicit locale_ref(const Locale& loc);
+
+  template <typename Locale, FMT_ENABLE_IF(sizeof(Locale::collate) != 0)>
+  locale_ref(const Locale& loc);

which is an ABI change for platforms like amd64-gnu-linux:

-_ZN3fmt3v116detail10locale_refC1ISt6localeEERKT_
+_ZN3fmt3v116detail10locale_refC1ISt6localeLi0EEERKT_

I am reporting this because ABI seems to be important to fmtlib (cf. commit 3e04222).
ABI break observed by end-user at https://bugzilla.suse.com/show_bug.cgi?id=1235078 .

[vitaut]

This was non-intentional, will look into restoring the ABI compatibility. Thanks for reporting!

[vitaut]

The ABI compatibility should be restored by 21aa095 which effectively reverts ff92223. @jengelh, could you confirm that it resolves the issue (then we'll make a patch release)?

[jengelh]

looks good

[vitaut]

Patch release that includes the fix: https://github.com/fmtlib/fmt/releases/tag/11.1.2.

[hgkjshegfskef]

@vitaut in case you are interested in a more comprehensive approach to determining ABI breakages, there are some automated tools for that, e.g. https://sourceware.org/libabigail/manual/abidiff.html