General IBM extensions

The following features are enabled by default at all extended language levels:

Table 1. General IBM extensions
Language feature	Discussed in:
Allowed types in `typedef` definitions	typedef definitions
Extended types allowed in bit field structure members	Bit field members

The following features are disabled by default at all language levels. It also can be enabled or disabled by an individual option.

Table 2. General IBM extensions with individual option controls
Language feature	Discussed in:	Individual option controls
`__static_assert` keyword	Keywords for language extensions (IBM extension)	-q[no]keyword=__static_assert
Extra text after #endif or #else	Extension of #endif and #else (IBM extension)	-qlanglvl=[no]textafterendif

The following feature is enabled by default with the xlc, xlc++, xlC, cc and c99 invocation commands when the extc99, stdc99, or extc1x language level is not in effect. It can also be enabled or disabled by a specific compiler option, listed in the following table:

Table 3. General IBM extensions with individual option controls
Language feature	Discussed in:	Individual option controls
Non-C99 IBM `long long` extension	Types of integer literals outside of C99 and C++11	-q[no]longlong

The following feature is enabled by default with the xlc, xlc++, xlC, cc and c99 invocation commands when the extc99, stdc99, or extc1x language level is in effect.

Table 4. General IBM extensions
Language feature	Discussed in:
C99 `long long` feature with the associated IBM extensions	Types of integer literals in C99 and C++11