+/* If SCM_DEBUG_CELL_ACCESSES is set to 1, cell accesses will perform
+ * exhaustive parameter checking: It will be verified that cell parameters
+ * actually point to a valid heap cell. Note: If this option is enabled,
+ * guile will run about ten times slower than normally.
+ */
+#ifndef SCM_DEBUG_CELL_ACCESSES
+#define SCM_DEBUG_CELL_ACCESSES SCM_DEBUG
+#endif
+
+/* If SCM_DEBUG_INTERRUPTS is set to 1, with every deferring and allowing of
+ * interrupts a consistency check will be performed.
+ */
+#ifndef SCM_DEBUG_INTERRUPTS
+#define SCM_DEBUG_INTERRUPTS SCM_DEBUG
+#endif
+
+/* If SCM_DEBUG_PAIR_ACCESSES is set to 1, accesses to cons cells will be
+ * exhaustively checked. Note: If this option is enabled, guile will run
+ * slower than normally.
+ */
+#ifndef SCM_DEBUG_PAIR_ACCESSES
+#define SCM_DEBUG_PAIR_ACCESSES SCM_DEBUG
+#endif
+
+/* If SCM_DEBUG_REST_ARGUMENT is set to 1, functions that take rest arguments
+ * will check whether the rest arguments are actually passed as a proper list.
+ * Otherwise, if SCM_DEBUG_REST_ARGUMENT is 0, functions that take rest
+ * arguments will take it for granted that these are passed as a proper list.
+ */
+#ifndef SCM_DEBUG_REST_ARGUMENT
+#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
+
+/* If SCM_DEBUG_DEBUGGING_SUPPORT is set to 1, guile will provide a set of
+ * special functions that support debugging with a debugger like gdb or
+ * debugging of guile internals on the scheme level. The behaviour of guile
+ * is not changed by this macro, only the set of functions that are available
+ * will differ. All functions that are introduced this way have the prefix
+ * 'scm_dbg_' on the C level and the prefix 'dbg-' on the scheme level. This
+ * allows to easily determine the set of support functions, given that your
+ * debugger or repl provide automatic name completion. Note that these
+ * functions are intended to be used during interactive debugging sessions
+ * only. They are not considered part of guile's official API. They may
+ * change or disappear without notice or deprecation phase.
+ */
+#ifndef SCM_DEBUG_DEBUGGING_SUPPORT
+#define SCM_DEBUG_DEBUGGING_SUPPORT SCM_DEBUG
+#endif