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(autoconf.info)Test Programs

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Running Test Programs
---------------------

   Use the following macro if you need to test run-time behavior of the
system while configuring.

 - Macro: AC_TRY_RUN (PROGRAM, [ACTION-IF-TRUE], [ACTION-IF-FALSE],
          [ACTION-IF-CROSS-COMPILING])
     If PROGRAM compiles and links successfully and returns an exit
     status of 0 when executed, run shell commands ACTION-IF-TRUE.
     Otherwise, run shell commands ACTION-IF-FALSE.

     This macro double quotes PROGRAM, the text of a program in the
     current language (Note: Language Choice), on which shell
     variable and back quote substitutions are performed.  This macro
     uses `CFLAGS' or `CXXFLAGS', `CPPFLAGS', `LDFLAGS', and `LIBS'
     when compiling.

     If the C compiler being used does not produce executables that run
     on the system where `configure' is being run, then the test
     program is not run.  If the optional shell commands
     ACTION-IF-CROSS-COMPILING are given, they are run instead.
     Otherwise, `configure' prints an error message and exits.

     In the ACTION-IF-FALSE section, the exit status of the program is
     available in the shell variable `$?', but be very careful to limit
     yourself to positive values smaller than 127; bigger values shall
     be saved into a file by the PROGRAM.  Note also that you have
     simply no guarantee that this exit status is issued by the
     PROGRAM, or by the failure of its compilation.  In other words,
     use this feature if sadist only, it was reestablished because the
     Autoconf maintainers grew tired of receiving "bug reports".

   Try to provide a pessimistic default value to use when
cross-compiling makes run-time tests impossible.  You do this by
passing the optional last argument to `AC_TRY_RUN'.  `autoconf' prints
a warning message when creating `configure' each time it encounters a
call to `AC_TRY_RUN' with no ACTION-IF-CROSS-COMPILING argument given.
You may ignore the warning, though users will not be able to configure
your package for cross-compiling.  A few of the macros distributed with
Autoconf produce this warning message.

   To configure for cross-compiling you can also choose a value for
those parameters based on the canonical system name (Note: Manual
Configuration).  Alternatively, set up a test results cache file with
the correct values for the host system (Note: Caching Results).

   To provide a default for calls of `AC_TRY_RUN' that are embedded in
other macros, including a few of the ones that come with Autoconf, you
can call `AC_PROG_CC' before running them.  Then, if the shell variable
`cross_compiling' is set to `yes', use an alternate method to get the
results instead of calling the macros.