[no%]conststrings

Enables or disables the placement of string literals in read-only memory. The default is -features=conststrings which places string literals into the read-only data section. Note that compiling a program that attempts to write to the memory location of a string literal will now cause a segmentation fault when compiled with this option.

extensions

Allows zero-sized struct/union declarations and void functions with return statements returning a value to work. 

extinl

Generates extern inline functions as global functions. This is the default, which conforms to the 1999 C standard. Compile new codes with -features=no%extinl to obtain the same treatment of extern inline functions as provided by older versions of the C and C++ compilers.

no%extinl

Generates extern inline functions as static functions. 

%none

The option is disabled.