Fix bug #15841 with assertion violations due to newline cache.

 src/insdel.c (invalidate_buffer_caches): New function, consolidated
 from part of prepare_to_modify_buffer.
 (insert_from_gap, prepare_to_modify_buffer):
 src/coding.c (code_convert_region, code_convert_string): Call
 invalidate_buffer_caches.
 src/lisp.h (invalidate_buffer_caches): Add prototype.

4 files changed, 52 insertions, 12 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 2b88d076b8c..a2dfa5bf613 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,13 @@
+2013-11-18  Eli Zaretskii  <eliz@gnu.org>
+
+        * insdel.c (invalidate_buffer_caches): New function, consolidated
+        from part of prepare_to_modify_buffer.
+        (insert_from_gap, prepare_to_modify_buffer):
+        * coding.c (code_convert_region, code_convert_string): Call
+        invalidate_buffer_caches.  (Bug#15841)
+
+        * lisp.h (invalidate_buffer_caches): Add prototype.
+
 2013-11-17  Eli Zaretskii  <eliz@gnu.org>
 
         * w32term.c (x_update_window_end): Don't invalidate the entire
diff --git a/src/coding.c b/src/coding.c
index ac828a48683..6c0633f2d93 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -9358,6 +9358,14 @@ code_convert_region (Lisp_Object start, Lisp_Object end,
   setup_coding_system (coding_system, &coding);
   coding.mode |= CODING_MODE_LAST_BLOCK;
 
+  if (BUFFERP (dst_object) && !EQ (dst_object, src_object))
+    {
+      struct buffer *buf = XBUFFER (dst_object);
+      ptrdiff_t buf_pt = BUF_PT (buf);
+
+      invalidate_buffer_caches (buf, buf_pt, buf_pt);
+    }
+
   if (encodep)
     encode_coding_object (&coding, src_object, from, from_byte, to, to_byte,
                           dst_object);
@@ -9447,6 +9455,15 @@ code_convert_string (Lisp_Object string, Lisp_Object coding_system,
   coding.mode |= CODING_MODE_LAST_BLOCK;
   chars = SCHARS (string);
   bytes = SBYTES (string);
+
+  if (BUFFERP (dst_object))
+    {
+      struct buffer *buf = XBUFFER (dst_object);
+      ptrdiff_t buf_pt = BUF_PT (buf);
+
+      invalidate_buffer_caches (buf, buf_pt, buf_pt);
+    }
+
   if (encodep)
     encode_coding_object (&coding, string, 0, 0, chars, bytes, dst_object);
   else
diff --git a/src/insdel.c b/src/insdel.c
index 5515b641d66..8de4f095396 100644
--- a/src/insdel.c
+++ b/src/insdel.c
@@ -993,6 +993,11 @@ insert_from_gap (ptrdiff_t nchars, ptrdiff_t nbytes, bool text_at_gap_tail)
   if (NILP (BVAR (current_buffer, enable_multibyte_characters)))
     nchars = nbytes;
 
+  /* No need to call prepare_to_modify_buffer, since this is called
+     from places that replace some region with a different text, so
+     prepare_to_modify_buffer was already called by the deletion part
+     of this dance.  */
+  invalidate_buffer_caches (current_buffer, GPT, GPT);
   record_insert (GPT, nchars);
   MODIFF++;
 
@@ -1869,19 +1874,26 @@ prepare_to_modify_buffer (ptrdiff_t start, ptrdiff_t end,
                           ptrdiff_t *preserve_ptr)
 {
   prepare_to_modify_buffer_1 (start, end, preserve_ptr);
+  invalidate_buffer_caches (current_buffer, start, end);
+}
 
-  if (current_buffer->newline_cache)
-    invalidate_region_cache (current_buffer,
-                             current_buffer->newline_cache,
-                             start - BEG, Z - end);
-  if (current_buffer->width_run_cache)
-    invalidate_region_cache (current_buffer,
-                             current_buffer->width_run_cache,
-                             start - BEG, Z - end);
-  if (current_buffer->bidi_paragraph_cache)
-    invalidate_region_cache (current_buffer,
-                             current_buffer->bidi_paragraph_cache,
-                             start - BEG, Z - end);
+/* Invalidate the caches maintained by the buffer BUF, if any, for the
+   region between buffer positions START and END.  */
+void
+invalidate_buffer_caches (struct buffer *buf, ptrdiff_t start, ptrdiff_t end)
+{
+  if (buf->newline_cache)
+    invalidate_region_cache (buf,
+                             buf->newline_cache,
+                             start - BUF_BEG (buf), BUF_Z (buf) - end);
+  if (buf->width_run_cache)
+    invalidate_region_cache (buf,
+                             buf->width_run_cache,
+                             start - BUF_BEG (buf), BUF_Z (buf) - end);
+  if (buf->bidi_paragraph_cache)
+    invalidate_region_cache (buf,
+                             buf->bidi_paragraph_cache,
+                             start - BUF_BEG (buf), BUF_Z (buf) - end);
 }
 
 /* These macros work with an argument named `preserve_ptr'
diff --git a/src/lisp.h b/src/lisp.h
index 926b83d7ce0..a5aec41be38 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -3479,6 +3479,7 @@ extern Lisp_Object del_range_2 (ptrdiff_t, ptrdiff_t,
 extern void modify_text (ptrdiff_t, ptrdiff_t);
 extern void prepare_to_modify_buffer (ptrdiff_t, ptrdiff_t, ptrdiff_t *);
 extern void prepare_to_modify_buffer_1 (ptrdiff_t, ptrdiff_t, ptrdiff_t *);
+extern void invalidate_buffer_caches (struct buffer *, ptrdiff_t, ptrdiff_t);
 extern void signal_after_change (ptrdiff_t, ptrdiff_t, ptrdiff_t);
 extern void adjust_after_insert (ptrdiff_t, ptrdiff_t, ptrdiff_t,
                                  ptrdiff_t, ptrdiff_t);