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(autoconf.info)Language Choice

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Language Choice
===============

   Autoconf-generated `configure' scripts check for the C compiler and
its features by default.  Packages that use other programming languages
(maybe more than one, e.g. C and C++) need to test features of the
compilers for the respective languages.  The following macros determine
which programming language is used in the subsequent tests in
`configure.ac'.

 - Macro: AC_LANG (LANGUAGE)
     Do compilation tests using the compiler, preprocessor and file
     extensions for the specified LANGUAGE.

     Supported languages are:

    `C'
          Do compilation tests using `CC' and `CPP' and use extension
          `.c' for test programs.

    `C++'
          Do compilation tests using `CXX' and `CXXCPP' and use
          extension `.C' for test programs.

    `Fortran 77'
          Do compilation tests using `F77' and use extension `.f' for
          test programs.

 - Macro: AC_LANG_PUSH (LANGUAGE)
     Remember the current language (as set by `AC_LANG') on a stack, and
     then select the LANGUAGE.  Use this macro and `AC_LANG_POP' in
     macros that need to temporarily switch to a particular language.

 - Macro: AC_LANG_POP ([LANGUAGE])
     Select the language that is saved on the top of the stack, as set
     by `AC_LANG_PUSH', and remove it from the stack.

     If given, LANGUAGE specifies the language we just _quit_.  It is a
     good idea to specify it when it's known (which should be the
     case...), since Autoconf will detect inconsistencies.

          AC_LANG_PUSH(Fortran 77)
          # Perform some tests on Fortran 77.
          # ...
          AC_LANG_POP(Fortran 77)

 - Macro: AC_REQUIRE_CPP
     Ensure that whichever preprocessor would currently be used for
     tests has been found.  Calls `AC_REQUIRE' (Note: Prerequisite
     Macros) with an argument of either `AC_PROG_CPP' or
     `AC_PROG_CXXCPP', depending on which language is current.