make get_region_bytecount end-exclusive

src/nvim/api/buffer.c

@@ -442,7 +442,7 @@ void nvim_buf_set_lines(uint64_t channel_id,
     goto end;
   }
 
-  bcount_t deleted_bytes = MAX(get_region_bytecount(start, end, 0, 0)-1, 0);
+  bcount_t deleted_bytes = get_region_bytecount(curbuf, start, end, 0, 0);
 
   // If the size of the range is reducing (ie, new_len < old_len) we
   // need to delete some old_len. We do this at the start, by

src/nvim/ops.c

@@ -1677,8 +1677,8 @@ int op_delete(oparg_T *oap)
       curbuf_splice_pending++;
       pos_T startpos = curwin->w_cursor;  // start position for delete
       bcount_t deleted_bytes = get_region_bytecount(
-          startpos.lnum, oap->end.lnum, startpos.col,
+          curbuf, startpos.lnum, oap->end.lnum, startpos.col,
-          oap->end.col) - !oap->inclusive;
+          oap->end.col) + oap->inclusive;
       truncate_line(true);        // delete from cursor to end of line
 
       curpos = curwin->w_cursor;  // remember curwin->w_cursor
@@ -6300,19 +6300,32 @@ bool op_reg_set_previous(const char name)
   return true;
 }
 
-bcount_t get_region_bytecount(linenr_T start_lnum, linenr_T end_lnum,
+/// Get the byte count of buffer region. End-exclusive.
-                              colnr_T start_col, colnr_T end_col)
+///
+/// @return number of bytes
+bcount_t get_region_bytecount(buf_T *buf, linenr_T start_lnum,
+                              linenr_T end_lnum, colnr_T start_col,
+                              colnr_T end_col)
 {
-  const char *first = (const char *)ml_get(start_lnum);
+  linenr_T max_lnum = buf->b_ml.ml_line_lnum;
+  if (start_lnum > max_lnum) {
+    return 0;
+  }
+  if (start_lnum == end_lnum) {
+    return end_col - start_col;
+  }
+  const char *first = (const char *)ml_get_buf(buf, start_lnum, false);
   bcount_t deleted_bytes = (bcount_t)STRLEN(first) - start_col + 1;
 
-  if (start_lnum == end_lnum) {
-    return deleted_bytes - ((bcount_t)STRLEN(first) - end_col + 1);
-  }
-
   for (linenr_T i = 1; i <= end_lnum-start_lnum-1; i++) {
+    if (start_lnum + i > max_lnum) {
+      return deleted_bytes;
+    }
     deleted_bytes += (bcount_t)STRLEN(
-        ml_get(start_lnum + i)) + 1;
+        ml_get_buf(buf, start_lnum + i, false)) + 1;
   }
-  return deleted_bytes + end_col + 1;
+  if (end_lnum > max_lnum) {
+    return deleted_bytes;
+  }
+  return deleted_bytes + end_col;
 }

test/functional/lua/buffer_updates_spec.lua

@@ -962,20 +962,20 @@ describe('lua: nvim_buf_attach on_bytes', function()
       local check_events = setup_eventcheck(verify, {"AAA", "BBB"})
 
       -- delete
-      command("lua vim.api.nvim_buf_set_lines(0, 0, 1, true, {})")
+      meths.buf_set_lines(0, 0, 1, true, {})
 
       check_events {
         { "test1", "bytes", 1, 3, 0, 0, 0, 1, 0, 4, 0, 0, 0 };
       }
 
       -- add
-      command("lua vim.api.nvim_buf_set_lines(0, 0, 0, true, {'asdf'})")
+      meths.buf_set_lines(0, 0, 0, true, {'asdf'})
       check_events {
         { "test1", "bytes", 1, 4, 0, 0, 0, 0, 0, 0, 1, 0, 5 };
       }
 
       -- replace
-      command("lua vim.api.nvim_buf_set_lines(0, 0, 1, true, {'asdf', 'fdsa'})")
+      meths.buf_set_lines(0, 0, 1, true, {'asdf', 'fdsa'})
       check_events {
         { "test1", "bytes", 1, 5, 0, 0, 0, 1, 0, 5, 2, 0, 10 };
       }