fixed autoconf so that ffi.h and libffi are checked iff ffi is

enabled.  Also made prep-callback return #f if libffi does not
support closures.

configure

@@ -6650,13 +6650,12 @@ ac_cv_lib_gmp=ac_cv_lib_gmp_main
 # Check whether --enable-libffi was given.
 if test "${enable_libffi+set}" = set; then
   enableval=$enable_libffi;
-cat >>confdefs.h <<\_ACEOF
-#define ENABLE_LIBFFI 1
-_ACEOF
-
 fi
 
 
+if test "$enable_libffi" = "yes"; then
+
+
 for ac_header in ffi.h
 do
 as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
@@ -6804,8 +6803,7 @@ as_val=`eval 'as_val=${'$as_ac_Header'}
 _ACEOF
 
 else
-  if test "$enable_libffi" = "yes"; then
+  { { $as_echo "$as_me:$LINENO: error: ffi.h cannot be found.
-    { { $as_echo "$as_me:$LINENO: error: ffi.h cannot be found.
 Please specify the location of the header file using
   ./configure CFLAGS=-I<path/to/ffi.h>   <other-options ...>
 " >&5
@@ -6814,12 +6812,12 @@ Please specify the location of the header file using
   ./configure CFLAGS=-I<path/to/ffi.h>   <other-options ...>
 " >&2;}
    { (exit 1); exit 1; }; }
-  fi
 fi
 
 done
 
 
+
 { $as_echo "$as_me:$LINENO: checking for ffi_call in -lffi" >&5
 $as_echo_n "checking for ffi_call in -lffi... " >&6; }
 if test "${ac_cv_lib_ffi_ffi_call+set}" = set; then
@@ -6893,8 +6891,7 @@ _ACEOF
   LIBS="-lffi $LIBS"
 
 else
-  if test "$enable_libffi" = "yes"; then
+  { { $as_echo "$as_me:$LINENO: error: libffi cannot be found.
-    { { $as_echo "$as_me:$LINENO: error: libffi cannot be found.
 Please specify the location of the library file using
   ./configure LDFLAGS=-L<path/to/libffi.ld|dylib|so|etc.>  <other-options ...>
 " >&5
@@ -6903,10 +6900,17 @@ Please specify the location of the library file using
   ./configure LDFLAGS=-L<path/to/libffi.ld|dylib|so|etc.>  <other-options ...>
 " >&2;}
    { (exit 1); exit 1; }; }
-  fi
 fi
 
 
+
+cat >>confdefs.h <<\_ACEOF
+#define ENABLE_LIBFFI 1
+_ACEOF
+
+
+fi
+
 # Checks for typedefs, structures, and compiler characteristics.
 { $as_echo "$as_me:$LINENO: checking for an ANSI C-conforming const" >&5
 $as_echo_n "checking for an ANSI C-conforming const... " >&6; }

configure.ac

@@ -64,22 +64,25 @@ ERROR: libgmp.so) if libgmp is installed in a non-standard location.
 ERROR: libgmp can be obtained from <http://gmplib.org>. ])])
 
 AC_ARG_ENABLE(libffi,
-  [  --enable-libffi     enable support for libffi.],
+  [  --enable-libffi     enable support for libffi.])
-  AC_DEFINE(ENABLE_LIBFFI, 1, [adds support for libffi]))
+
+if test "$enable_libffi" = "yes"; then
+
 AC_CHECK_HEADERS([ffi.h],,
-  if test "$enable_libffi" = "yes"; then
     AC_MSG_ERROR([ffi.h cannot be found.
 Please specify the location of the header file using
   ./configure CFLAGS=-I<path/to/ffi.h>   <other-options ...>
-])
+]))
-  fi)
+
 AC_CHECK_LIB(ffi,ffi_call,,
-  if test "$enable_libffi" = "yes"; then
     AC_MSG_ERROR([libffi cannot be found.
 Please specify the location of the library file using
   ./configure LDFLAGS=-L<path/to/libffi.ld|dylib|so|etc.>  <other-options ...>
-])
+]))
-  fi)
+
+AC_DEFINE(ENABLE_LIBFFI, 1, [adds support for libffi])
+
+fi
 
 # Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST

scheme/last-revision

@@ -1 +1 @@
-1601
+1602

src/ikarus-ffi.c

@@ -319,6 +319,7 @@ generic_callback(ffi_cif *cif, void *ret, void **args, void *user_data){
 
 ikptr
 ikrt_prepare_callback(ikptr data, ikpcb* pcb){
+#if FFI_CLOSURES
   ikptr cifptr = ref(data, off_vector_data + 0 * wordsize);
   void* codeloc;
   ffi_closure* closure = ffi_closure_alloc(sizeof(ffi_closure), &codeloc);
@@ -346,6 +347,9 @@ ikrt_prepare_callback(ikptr data, ikpcb* pcb){
   ref(p, 0) = pointer_tag;
   ref(p, wordsize) = (ikptr) codeloc;
   return p+vector_tag;
+#else
+  return false_object
+#endif
 }
 
 int ho (int(*f)(int), int n) {