Stop assuming interval pointers and lisp objects can be distinguished by

inspection.  Beginnings of support for expensive internal consistency checks.

* config.in (ENABLE_CHECKING): Undef.

* lisp.h (struct interval): Replace "parent" field with a union of interval
pointer and Lisp_Object; add new bitfield to use as discriminant.  Change other
flag fields to bitfields.
(CHECK): New macro for consistency checking.  If ENABLE_CHECKING is defined and
the supplied test fails, print a message and abort.
(eassert): New macro.  Use CHECK to provide an assert-like facility.

* intervals.h (NULL_INTERVAL_P): Now applies only to real interval pointers;
abort if the value looks like a lisp object.
(NULL_INTERVAL_P, NULL_PARENT, HAS_PARENT, HAS_OBJECT, SET_PARENT, SET_OBJECT,
INTERVAL_PARENT, GET_INTERVAL_OBJECT, COPY_PARENT): Modify for new interval
parent definition.

* alloc.c (mark_interval_tree, MARK_INTERVAL_TREE, UNMARK_BALANCE_INTERVALS):
Update references that need an addressable lisp object in the interval
structure.
(die): New function.
(suppress_checking): New variable.

* intervals.c (interval_start_pos): Just return 0 if there's no parent object.

1 files changed, 15 insertions, 3 deletions

diff --git a/src/alloc.c b/src/alloc.c
index d7e4214c6c4..3b5d0e57ace 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -766,7 +766,7 @@ mark_interval_tree (tree)
 
   /* XMARK expands to an assignment; the LHS of an assignment can't be
      a cast.  */
-  XMARK (* (Lisp_Object *) &tree->parent);
+  XMARK (tree->up.obj);
 
   traverse_intervals (tree, 1, 0, mark_interval, Qnil);
 }
@@ -777,7 +777,7 @@ mark_interval_tree (tree)
 #define MARK_INTERVAL_TREE(i)                           \
   do {                                                  \
     if (!NULL_INTERVAL_P (i)                            \
-        && ! XMARKBIT (*(Lisp_Object *) &i->parent))    \
+        && ! XMARKBIT (i->up.obj))                      \
       mark_interval_tree (i);                           \
   } while (0)
 
@@ -790,7 +790,7 @@ mark_interval_tree (tree)
   do {                                                  \
    if (! NULL_INTERVAL_P (i))                           \
      {                                                  \
-       XUNMARK (* (Lisp_Object *) (&(i)->parent));      \
+       XUNMARK ((i)->up.obj);                           \
        (i) = balance_intervals (i);                     \
      }                                                  \
   } while (0)
@@ -4649,6 +4649,18 @@ Frames, windows, buffers, and subprocesses count as vectors\n\
 
   return Flist (8, consed);
 }
+
+int suppress_checking;
+void
+die (msg, file, line)
+     const char *msg;
+     const char *file;
+     int line;
+{
+  fprintf (stderr, "\r\nEmacs fatal error: %s:%d: %s\r\n",
+           file, line, msg);
+  abort ();
+}
 
 /* Initialization */