Revert "SCM is either a union or scm_t_bits"

This reverts commit 80125469ef95f6d8d46a26619fb2f85151f32719.

Conflicts:

	libguile/__scm.h

1 files changed, 25 insertions, 0 deletions

diff --git a/libguile/__scm.h b/libguile/__scm.h
index 3a8b07a6f..ee73855c6 100644
--- a/libguile/__scm.h
+++ b/libguile/__scm.h
@@ -273,6 +273,31 @@
 #define SCM_DEBUG_REST_ARGUMENT SCM_DEBUG
 #endif
 
+/* The macro SCM_DEBUG_TYPING_STRICTNESS indicates what level of type checking
+ * shall be performed with respect to the use of the SCM datatype.  The macro
+ * may be defined to one of the values 0, 1 and 2.
+ *
+ * A value of 0 means that there will be no compile time type checking, since
+ * the SCM datatype will be declared as an integral type.  This setting should
+ * only be used on systems, where casting from integral types to pointers may
+ * lead to loss of bit information.
+ *
+ * A value of 1 means that there will an intermediate level of compile time
+ * type checking, since the SCM datatype will be declared as a pointer to an
+ * undefined struct.  This setting is the default, since it does not cost
+ * anything in terms of performance or code size.
+ *
+ * A value of 2 provides a maximum level of compile time type checking since
+ * the SCM datatype will be declared as a struct.  This setting should be used
+ * for _compile time_ type checking only, since the compiled result is likely
+ * to be quite inefficient.  The right way to make use of this option is to do
+ * a 'make clean; make CFLAGS=-DSCM_DEBUG_TYPING_STRICTNESS=2', fix your
+ * errors, and then do 'make clean; make'.
+ */
+#ifndef SCM_DEBUG_TYPING_STRICTNESS
+#define SCM_DEBUG_TYPING_STRICTNESS 1
+#endif
+
 
 
 /* {Feature Options}