Occasionally you need a macro that Autoconf doesn't quite provide. That's when it pays to know how to copy and modify existing Autoconf macros.
For example, here's a solution to a common Autoconf mailing list issue. A user wants to use
AC_CHECK_LIB to capture a desired library in the
LIBS variable. The catch is that this library exports functions with C++, rather than C linkage.
AC_CHECK_LIB is not very accommodating when it comes to C++, primarily because
AC_CHECK_LIB makes certain assumptions about symbols exported with C linkage that just don't apply to C++ symbols.
For example, the widely known (and standardized) rules of C linkage state that an exported C-linkage symbol (also known as the
cdecl calling convention ...