Re: [Openexr-devel] A few fixes before the 1.1.0 release

[Brad Hards]

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On Tue, 03 Feb 2004 07:48 am, Drew Hess wrote:
> It's easy to have autoconf detect whether the compiler supports "restrict"
> or not and choose the appropriate flag when building OpenEXR.
Indeed - it already does this as I understand.

> The problem occurs when the developer is using Imath in her own project.
> We can't put the flag in the pkg-config file because the developer can use
> a different compiler to compile the app than the compiler used to compile
> OpenEXR itself.  So that puts on the burden on the developer to use the
> right flag in order to get Imath to compile, which I don't wanna do.
Another option might be to distribute a macro that goes into
$prefix/share/aclocal (or whatever is appropriate) that detects the Right
Thing To Do, and sets the compiler flags.

Anyone using autoconf already needs tests - we provide the tests, and include
the right option for handling the restrict keyword. Here are my tests (which 
don't
have handling for restrict, and the variable names could be make more
regular, but you get the idea:
AC_DEFUN(AC_FIND_LIBEXR,
[
AC_REQUIRE([AC_FIND_ZLIB])
AC_CACHE_VAL(ac_cv_libexr,
[
  if test -z "$PKG_CONFIG"; then
    AC_PATH_PROG(PKG_CONFIG, pkg-config, no)
  fi

  AC_MSG_CHECKING([for OpenEXR libraries])

  if test "$PKG_CONFIG" = "no" ; then
     AC_MSG_RESULT(no)
     echo "*** The pkg-config script could not be found. Make sure it is"
     echo "*** in your path, or set the PKG_CONFIG environment variable"
     echo "*** to the full path to pkg-config."
     echo "*** Or see http://www.freedesktop.org/software/pkgconfig to get 
pkg-config."
  else
     if !(`$PKG_CONFIG --exists OpenEXR`) ; then
        AC_MSG_RESULT(no)
        echo "*** pkg-config installed, but no OpenEXR Libraries were found ***"
        echo "*** Install OpenEXR package (from http:///www.openexr.org)"
        echo "*** if you want EXR image format support"
     else
        if !(`$PKG_CONFIG --atleast-version="1.0.7" OpenEXR`) ; then
           AC_MSG_RESULT(no)
           echo "*** OpenEXR libraries were found, but at least version 1.0.7 
is required ***"
           echo "*** Install newer OpenEXR package (from 
http:///www.openexr.org)"
           echo "*** if you want EXR image format support"
        else
           kde_save_LIBS="$LIBS"
           LIBS="$LIBS $all_libraries $USER_LDFLAGS $LIBZ `pkg-config --libs 
OpenEXR`"
           AC_LANG_SAVE
           AC_LANG_CPLUSPLUS
           kde_save_CXXFLAGS="$CXXFLAGS"
           EXR_FLAGS=`$PKG_CONFIG --cflags OpenEXR`
           CXXFLAGS="$CXXFLAGS $all_includes $USER_INCLUDES $EXR_FLAGS"

           AC_TRY_LINK(dnl
               [
               #include <ImfRgbaFile.h>
               ],
               [
               using namespace Imf;
               RgbaInputFile file ("dummy");
               return 0;
               ],
               eval "ac_cv_libexr='$LIBZ `pkg-config --libs OpenEXR`'",
               eval "ac_cv_libexr=no"
           )
           LIBS="$kde_save_LIBS"
           CXXFLAGS="$kde_save_CXXFLAGS"
           AC_LANG_RESTORE
           ])dnl
           if eval "test ! \"`echo $ac_cv_libexr`\" = no"; then
               AC_DEFINE_UNQUOTED(HAVE_EXR, 1, [Define if you have OpenEXR])
               LIB_EXR="$ac_cv_libexr"
               AC_MSG_RESULT($ac_cv_libexr)
           else
               AC_MSG_RESULT(no)
               LIB_EXR=""
           fi
        fi
     fi
  fi
  AC_SUBST(LIB_EXR)
  AC_SUBST(EXR_FLAGS)
])

Then you just call AC_FIND_LIBEXR, and use LIB_EXR in the library
linker flags, and EXR_FLAGS in the compiler flags.

[This also needs a AC_FIND_ZLIB - we might think about that too, given
the bad experiences many projects have had bringing in a broken
zlib from the XFree86 project]

Brad
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