bug#24358: 25.1.50; re-search-forward errors with "Variable binding depth exceeds max-specpdl-size"

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 23 Oct 2016 22:10:55 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 24358@debbugs.gnu.org, npostavs@users.sourceforge.net
> 
> The problem is to find the code which causes this.  Hmm...

Sam, the patch below removes the changes done by Noam in an attempt to
solve the original report of this bug.  Please apply it, and see if
doing so allows you to complete your bootstrap without any errors.

Noam, do you configure Emacs with --enable-check-lisp-object-type?
If not, please do, because that's what Sam does; perhaps that is the
reason why he gets the problem and you don't.

One other difference is that Sam is running a bootstrap, so his
bootstrap-emacs used to build ja-dic has the necessary Lisp files
loaded as *.el files, not *.elc.  Therefore another thing to try
(perhaps even before reconfiguring) is a full bootstrap, preferably in
a separate clean directory, maybe you will see this problem then.

Your systems seem to be similar, so I'd expect you both to see the
same problems.

Here's the patch to remove Noam's changes and Paul's follow-up
changes:

diff --git a/src/dired.c b/src/dired.c
index 006f74c..dba575c 100644
--- a/src/dired.c
+++ b/src/dired.c
@@ -259,11 +259,9 @@ directory_files_internal (Lisp_Object directory, Lisp_Object full,
       QUIT;
 
       bool wanted = (NILP (match)
-		     || (re_match_object = name,
-                         re_search (bufp, SSDATA (name), len, 0, len, 0) >= 0));
+		     || re_search (bufp, SSDATA (name), len, 0, len, 0) >= 0);
 
       immediate_quit = 0;
-      re_match_object = Qnil;   /* Stop protecting name from GC.  */
 
       if (wanted)
 	{
diff --git a/src/regex.c b/src/regex.c
index b12e95b..164eb46 100644
--- a/src/regex.c
+++ b/src/regex.c
@@ -152,8 +152,6 @@
 
 /* Converts the pointer to the char to BEG-based offset from the start.  */
 # define PTR_TO_OFFSET(d) POS_AS_IN_BUFFER (POINTER_TO_OFFSET (d))
-/* Strings are 0-indexed, buffers are 1-indexed; we pun on the boolean
-   result to get the right base index.  */
 # define POS_AS_IN_BUFFER(p) ((p) + (NILP (re_match_object) || BUFFERP (re_match_object)))
 
 # define RE_MULTIBYTE_P(bufp) ((bufp)->multibyte)
@@ -1438,62 +1436,11 @@ typedef struct
 #define NEXT_FAILURE_HANDLE(h) fail_stack.stack[(h) - 3].integer
 #define TOP_FAILURE_HANDLE() fail_stack.frame
 
-#ifdef emacs
-# define STR_BASE_PTR(obj)			 \
-   (NILP (obj) ? current_buffer->text->beg	 \
-    : STRINGP (obj) ? SDATA (obj)		 \
-    : NULL)
-#else
-# define STR_BASE_PTR(obj) NULL
-#endif
 
 #define ENSURE_FAIL_STACK(space)					\
 while (REMAINING_AVAIL_SLOTS <= space) {				\
-  re_char *orig_base = STR_BASE_PTR (re_match_object);                  \
-  bool might_relocate = orig_base != NULL;				\
-  ptrdiff_t string1_off, end1_off, end_match_1_off;                     \
-  ptrdiff_t string2_off, end2_off, end_match_2_off;                     \
-  ptrdiff_t d_off, dend_off, dfail_off;                                 \
-  if (might_relocate)							\
-    {                                                                   \
-      if (string1)                                                      \
-        {                                                               \
-          string1_off = string1 - orig_base;                            \
-          end1_off = end1 - orig_base;                                  \
-          end_match_1_off = end_match_1 - orig_base;                    \
-        }                                                               \
-      if (string2)                                                      \
-        {                                                               \
-          string2_off = string2 - orig_base;                            \
-          end2_off = end2 - orig_base;                                  \
-          end_match_2_off = end_match_2 - orig_base;                    \
-        }                                                               \
-      d_off = d - orig_base;                                            \
-      dend_off = dend - orig_base;                                      \
-      dfail_off = dfail - orig_base;                                    \
-    }                                                                   \
   if (!GROW_FAIL_STACK (fail_stack))					\
     return -2;								\
-  /* In Emacs, GROW_FAIL_STACK might relocate string pointers.  */	\
-  if (might_relocate)							\
-    {                                                                   \
-      re_char *new_base = STR_BASE_PTR (re_match_object);		\
-      if (string1)                                                      \
-        {                                                               \
-          string1 = new_base + string1_off;                             \
-          end1 = new_base + end1_off;                                   \
-          end_match_1 = new_base + end_match_1_off;                     \
-        }                                                               \
-      if (string2)                                                      \
-        {                                                               \
-          string2 = new_base + string2_off;                             \
-          end2 = new_base + end2_off;                                   \
-          end_match_2 = new_base + end_match_2_off;                     \
-        }                                                               \
-      d = new_base + d_off;                                             \
-      dend = new_base + dend_off;                                       \
-      dfail = new_base + dfail_off;                                     \
-    }                                                                   \
   DEBUG_PRINT ("\n  Doubled stack; size now: %zd\n", (fail_stack).size);\
   DEBUG_PRINT ("	 slots available: %zd\n", REMAINING_AVAIL_SLOTS);\
 }
@@ -4380,10 +4327,6 @@ re_search_2 (struct re_pattern_buffer *bufp, const char *str1, size_t size1,
   /* Loop through the string, looking for a place to start matching.  */
   for (;;)
     {
-      ptrdiff_t offset1, offset2;
-      re_char *orig_base;
-      bool might_relocate;
-
       /* If the pattern is anchored,
 	 skip quickly past places we cannot match.
 	 We don't bother to treat startpos == 0 specially
@@ -4500,17 +4443,6 @@ re_search_2 (struct re_pattern_buffer *bufp, const char *str1, size_t size1,
 	  && !bufp->can_be_null)
 	return -1;
 
-      /* re_match_2_internal may allocate, relocating the Lisp text
-	 object that we're searching.  */
-      IF_LINT (offset2 = 0);  /* Work around GCC bug 78081.  */
-      orig_base = STR_BASE_PTR (re_match_object);
-      might_relocate = orig_base != NULL;
-      if (might_relocate)
-        {
-          if (string1) offset1 = string1 - orig_base;
-          if (string2) offset2 = string2 - orig_base;
-        }
-
       val = re_match_2_internal (bufp, string1, size1, string2, size2,
 				 startpos, regs, stop);
 
@@ -4520,13 +4452,6 @@ re_search_2 (struct re_pattern_buffer *bufp, const char *str1, size_t size1,
       if (val == -2)
 	return -2;
 
-      if (might_relocate)
-        {
-	  re_char *new_base = STR_BASE_PTR (re_match_object);
-          if (string1) string1 = offset1 + new_base;
-          if (string2) string2 = offset2 + new_base;
-        }
-
     advance:
       if (!range)
 	break;
@@ -4962,8 +4887,8 @@ WEAK_ALIAS (__re_match, re_match)
 #endif /* not emacs */
 
 #ifdef emacs
-/* In Emacs, this is the string or buffer in which we are matching.
-   See the declaration in regex.h for details.  */
+/* In Emacs, this is the string or buffer in which we
+   are matching.  It is used for looking up syntax properties.  */
 Lisp_Object re_match_object;
 #endif
 
diff --git a/src/search.c b/src/search.c
index 5c04916..dc7e2d8 100644
--- a/src/search.c
+++ b/src/search.c
@@ -287,10 +287,8 @@ looking_at_1 (Lisp_Object string, bool posix)
   immediate_quit = 1;
   QUIT;			/* Do a pending quit right away, to avoid paradoxical behavior */
 
-  /* Get pointers and sizes of the two strings that make up the
-     visible portion of the buffer.  Note that we can use pointers
-     here, unlike in search_buffer, because we only call re_match_2
-     once, after which we never use the pointers again.  */
+  /* Get pointers and sizes of the two strings
+     that make up the visible portion of the buffer. */
 
   p1 = BEGV_ADDR;
   s1 = GPT_BYTE - BEGV_BYTE;
@@ -409,7 +407,6 @@ string_match_1 (Lisp_Object regexp, Lisp_Object string, Lisp_Object start,
 		   (NILP (Vinhibit_changing_match_data)
 		    ? &search_regs : NULL));
   immediate_quit = 0;
-  re_match_object = Qnil;       /* Stop protecting string from GC.  */
 
   /* Set last_thing_searched only when match data is changed.  */
   if (NILP (Vinhibit_changing_match_data))
@@ -480,7 +477,6 @@ fast_string_match_internal (Lisp_Object regexp, Lisp_Object string,
 		   SBYTES (string), 0,
 		   SBYTES (string), 0);
   immediate_quit = 0;
-  re_match_object = Qnil;       /* Stop protecting string from GC.  */
   return val;
 }
 
@@ -568,7 +564,6 @@ fast_looking_at (Lisp_Object regexp, ptrdiff_t pos, ptrdiff_t pos_byte,
   len = re_match_2 (buf, (char *) p1, s1, (char *) p2, s2,
 		    pos_byte, NULL, limit_byte);
   immediate_quit = 0;
-  re_match_object = Qnil;       /* Stop protecting string from GC.  */
 
   return len;
 }
@@ -1183,8 +1178,8 @@ search_buffer (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
 
   if (RE && !(trivial_regexp_p (string) && NILP (Vsearch_spaces_regexp)))
     {
-      unsigned char *base;
-      ptrdiff_t off1, off2, s1, s2;
+      unsigned char *p1, *p2;
+      ptrdiff_t s1, s2;
       struct re_pattern_buffer *bufp;
 
       bufp = compile_pattern (string,
@@ -1198,19 +1193,16 @@ search_buffer (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
 				   can take too long. */
       QUIT;			/* Do a pending quit right away,
 				   to avoid paradoxical behavior */
-      /* Get offsets and sizes of the two strings that make up the
-         visible portion of the buffer.  We compute offsets instead of
-         pointers because re_search_2 may call malloc and therefore
-         change the buffer text address.  */
+      /* Get pointers and sizes of the two strings
+	 that make up the visible portion of the buffer. */
 
-      base = current_buffer->text->beg;
-      off1 = BEGV_ADDR - base;
+      p1 = BEGV_ADDR;
       s1 = GPT_BYTE - BEGV_BYTE;
-      off2 = GAP_END_ADDR - base;
+      p2 = GAP_END_ADDR;
       s2 = ZV_BYTE - GPT_BYTE;
       if (s1 < 0)
 	{
-          off2 = off1;
+	  p2 = p1;
 	  s2 = ZV_BYTE - BEGV_BYTE;
 	  s1 = 0;
 	}
@@ -1225,16 +1217,12 @@ search_buffer (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
 	{
 	  ptrdiff_t val;
 
-          val = re_search_2 (bufp,
-                             (char*) (base + off1), s1,
-                             (char*) (base + off2), s2,
+	  val = re_search_2 (bufp, (char *) p1, s1, (char *) p2, s2,
 			     pos_byte - BEGV_BYTE, lim_byte - pos_byte,
 			     (NILP (Vinhibit_changing_match_data)
 			      ? &search_regs : &search_regs_1),
 			     /* Don't allow match past current point */
 			     pos_byte - BEGV_BYTE);
-	  /* Update 'base' due to possible relocation inside re_search_2.  */
-	  base = current_buffer->text->beg;
 	  if (val == -2)
 	    {
 	      matcher_overflow ();
@@ -1274,15 +1262,11 @@ search_buffer (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
 	{
 	  ptrdiff_t val;
 
-          val = re_search_2 (bufp,
-                             (char*) (base + off1), s1,
-                             (char*) (base + off2), s2,
-                             pos_byte - BEGV_BYTE, lim_byte - pos_byte,
+	  val = re_search_2 (bufp, (char *) p1, s1, (char *) p2, s2,
+			     pos_byte - BEGV_BYTE, lim_byte - pos_byte,
 			     (NILP (Vinhibit_changing_match_data)
 			      ? &search_regs : &search_regs_1),
 			     lim_byte - BEGV_BYTE);
-	  /* Update 'base' due to possible relocation inside re_search_2.  */
-	  base = current_buffer->text->beg;
 	  if (val == -2)
 	    {
 	      matcher_overflow ();