bug#15841: Display bugs with cache-long-lines non-nil

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 12 Nov 2013 18:31:32 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 15841@debbugs.gnu.org
> 
> In any case, I already traced through the code that is involved, and
> the immediate reason for the assertion violation is that the cache
> isn't being updated wrt changes in buffer size (which are caused by
> decoding the stuff brought in by 'ls').  However, a naive attempt to
> force such updates didn't solve the whole problem: the aborts are
> gone, but the infloop is still there, and also other minor display
> issues.  So I guess there's another factor at work there...

I think I might have found a solution for this.  Could you please run
with the patch below for a while, and see if it gives good results?

=== modified file 'src/coding.c'
--- src/coding.c	2013-10-08 06:40:09 +0000
+++ src/coding.c	2013-11-15 16:27:56 +0000
@@ -9358,6 +9358,14 @@ code_convert_region (Lisp_Object start, 
   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,
   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

=== modified file 'src/insdel.c'
--- src/insdel.c	2013-11-11 05:18:53 +0000
+++ src/insdel.c	2013-11-15 16:27:56 +0000
@@ -993,6 +993,11 @@ insert_from_gap (ptrdiff_t nchars, ptrdi
   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 star
 			  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'

=== modified file 'src/lisp.h'
--- src/lisp.h	2013-11-15 08:18:37 +0000
+++ src/lisp.h	2013-11-15 16:27:56 +0000
@@ -3486,6 +3486,7 @@ extern Lisp_Object del_range_2 (ptrdiff_
 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);