Extensions for GNU C++ compatibility

The following GNU C++ language extension is enabled with the -qlanglvl=extended option, which is the default language level used when you compile with the xlC and xlc++ invocation commands. It can also be enabled or disabled by a specific compiler option, listed in the table below.

Table 41. IBM XL C++ language extensions for compatibility with GNU C++, with individual option controls
Language feature Discussed in: Individual option control
Template instantiations declared as extern Template instantiation (C++ only) -qlanglvl=[no]gnu_externtemplate