To check for a syntax feature of the current language's (see Language Choice) compiler, such as whether it recognizes a certain keyword, or
simply to try some library feature, use
AC_COMPILE_IFELSE to try
to compile a small program that uses that feature.
Run the compiler and compilation flags of the current language (see Language Choice) on the input, run the shell commands action-if-true on success, action-if-false otherwise. The input can be made by
It is customary to report unexpected failures with
AC_MSG_FAILURE. This macro does not try to link; use
AC_LINK_IFELSEif you need to do that (see Running the Linker). If needed, action-if-true can further access the just-compiled object file conftest.$OBJEXT.
This macro uses
AC_REQUIREfor the compiler associated with the current language, which means that if the compiler has not yet been determined, the compiler determination will be made prior to the body of the outermost
AC_DEFUNmacro that triggered this macro to expand (see Expanded Before Required).
For tests in Erlang, the input must be the source code of a module named
AC_COMPILE_IFELSE generates a conftest.beam
file that can be interpreted by the Erlang virtual machine (
ERL). It is
recommended to use
AC_LANG_PROGRAM to specify the test program,
to ensure that the Erlang module has the right name.