Macro: ac_check_typedef

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# ac_check_typedef

## Synopsis

`AC_CHECK_TYPEDEF_(TYPEDEF, HEADER [, ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND ]])`

## Version

1.1.1.1 (2001/07/26) guidod @ ac-archive-0.5.32

## Author

Guido Draheim <guidod@gmx.de>

## Description

check if the given typedef-name is recognized as a type. The trick is to use a sizeof(TYPEDEF) and see if the compiler is happy with that.

this can be thought of as a mixture of AC_CHECK_TYPE(TYPEDEF,DEFAULT) and AC_CHECK_LIB(LIBRARY,FUNCTION,ACTION-IF-FOUND,ACTION-IF-NOT-FOUND)

a convenience macro AC_CHECK_TYPEDEF_ is provided that will not emit any message to the user - it just executes one of the actions.

## M4 Source Code

    AC_DEFUN(AC_CHECK_TYPEDEF_,
    [dnl
    ac_lib_var=`echo $1['_']$2 | sed 'y%./+-%__p_%'`
    AC_CACHE_VAL(ac_cv_lib_$ac_lib_var,
    [ eval "ac_cv_type_$ac_lib_var='not-found'"
      ac_cv_check_typedef_header=`echo ifelse([$2], , stddef.h, $2)`
      AC_TRY_COMPILE( [#include <$ac_cv_check_typedef_header>],
    	[int x = sizeof($1); x = x;],
            eval "ac_cv_type_$ac_lib_var=yes" ,
            eval "ac_cv_type_$ac_lib_var=no" )
      if test `eval echo '$ac_cv_type_'$ac_lib_var` = "no" ; then
         ifelse([$4], , :, $4)
      else
         ifelse([$3], , :, $3)
      fi
    ])])

    dnl AC_CHECK_TYPEDEF(TYPEDEF, HEADER [, ACTION-IF-FOUND,
    dnl    [, ACTION-IF-NOT-FOUND ]])
    AC_DEFUN(AC_CHECK_TYPEDEF,
    [dnl
     AC_MSG_CHECKING([for $1 in $2])
     AC_CHECK_TYPEDEF_($1,$2,AC_MSG_RESULT(yes),AC_MSG_RESULT(no))dnl
    ])