const works different in C vs C++. In C++, a global "const" variable
has internal linkage by default, resulting in link errors like:
...
extension.o: In function `get_ext_lang_defn(extension_language)':
gdb/extension.c:126: undefined reference to `extension_language_guile'
gdb/extension.c:124: undefined reference to `extension_language_guile'
...
The fix is to define exported const objects with "extern const". But
that in C would not be a definition. So we need to #ifdef C vs C++ in
this case.
EXPORTED_CONST comes from include/ansidecl.h, but in the
feature_to_c.sh case I think it's better to leave the script with no
dependencies.
gdb/ChangeLog:
2015-02-27 Pedro Alves <palves@redhat.com>
* cp-valprint.c (vtbl_ptr_name): Use EXPORTED_CONST.
* guile/guile.c (extension_language_guile): Use EXPORTED_CONST.
* features/feature_to_c.sh: Tag the generated xml_builtin array
with extern const in C++ mode.
