Determine an Objective C compiler to use. If OBJC is not already
set in the environment, check for Objective C compilers. Set output
variable OBJC to the name of the compiler found.
This macro may, however, be invoked with an optional first argument
which, if specified, must be a blank-separated list of Objective C compilers to
search for. This just gives the user an opportunity to specify an
alternative search list for the Objective C compiler. For example, if you
didn’t like the default order, then you could invoke AC_PROG_OBJC
like this:
AC_PROG_OBJC([gcc objcc objc])
If using a compiler that supports GNU Objective C, set shell variable
GOBJC to ‘yes’. If output variable OBJCFLAGS was not
already set, set it to -g -O2 for a GNU Objective C
compiler (-O2 on systems where the compiler does not accept
-g), or -g for other compilers.
Set output variable OBJCPP to a command that runs the Objective C
preprocessor. If ‘$OBJC -E’ doesn’t work, tries cpp and
/lib/cpp, in that order. Because of this fallback, CXXCPP
may or may not set Objective-C-specific predefined macros (such as
__OBJC__).