vim-patch:9.1.0113: duplicate code when cleaning undo stack

Problem:  duplicate code when cleaning undo stack
Solution: refactor undo cleanup into a single public function

related: vim/vim#13928

9071ed8107

Co-authored-by: Christian Brabandt <cb@256bit.org>

src/nvim/buffer.c

@@ -843,8 +843,9 @@ void buf_freeall(buf_T *buf, int flags)
   ml_close(buf, true);              // close and delete the memline/memfile
   buf->b_ml.ml_line_count = 0;      // no lines in buffer
   if ((flags & BFA_KEEP_UNDO) == 0) {
-    u_blockfree(buf);               // free the memory allocated for undo
+    // free the memory allocated for undo
-    u_clearall(buf);                // reset all undo information
+    // and reset all undo information
+    u_clearallandblockfree(buf);
   }
   syntax_clear(&buf->b_s);          // reset syntax info
   buf->b_flags &= ~BF_READERR;      // a read error is no longer relevant

src/nvim/fileio.c

@@ -3171,8 +3171,7 @@ void buf_reload(buf_T *buf, int orig_mode, bool reload_options)
       // Mark the buffer as unmodified and free undo info.
       unchanged(buf, true, true);
       if ((flags & READ_KEEP_UNDO) == 0) {
-        u_blockfree(buf);
+        u_clearallandblockfree(buf);
-        u_clearall(buf);
       } else {
         // Mark all undo states as changed.
         u_unchanged(curbuf);

src/nvim/quickfix.c

@@ -4159,8 +4159,7 @@ static void qf_fill_buffer(qf_list_T *qfl, buf_T *buf, qfline_T *old_last, int q
     }
 
     // Remove all undo information
-    u_blockfree(curbuf);
+    u_clearallandblockfree(curbuf);
-    u_clearall(curbuf);
   }
 
   // Check if there is anything to display

src/nvim/undo.c

@@ -2988,6 +2988,28 @@ void u_clearall(buf_T *buf)
   buf->b_u_line_lnum = 0;
 }
 
+/// Free all allocated memory blocks for the buffer 'buf'.
+void u_blockfree(buf_T *buf)
+{
+  while (buf->b_u_oldhead != NULL) {
+#ifndef NDEBUG
+    u_header_T *previous_oldhead = buf->b_u_oldhead;
+#endif
+
+    u_freeheader(buf, buf->b_u_oldhead, NULL);
+    assert(buf->b_u_oldhead != previous_oldhead);
+  }
+  xfree(buf->b_u_line_ptr);
+}
+
+/// Free all allocated memory blocks for the buffer 'buf'.
+/// and invalidate the undo buffer
+void u_clearallandblockfree(buf_T *buf)
+{
+  u_blockfree(buf);
+  u_clearall(buf);
+}
+
 /// Save the line "lnum" for the "U" command.
 void u_saveline(buf_T *buf, linenr_T lnum)
 {
@@ -3054,20 +3076,6 @@ void u_undoline(void)
   check_cursor_col();
 }
 
-/// Free all allocated memory blocks for the buffer 'buf'.
-void u_blockfree(buf_T *buf)
-{
-  while (buf->b_u_oldhead != NULL) {
-#ifndef NDEBUG
-    u_header_T *previous_oldhead = buf->b_u_oldhead;
-#endif
-
-    u_freeheader(buf, buf->b_u_oldhead, NULL);
-    assert(buf->b_u_oldhead != previous_oldhead);
-  }
-  xfree(buf->b_u_line_ptr);
-}
-
 /// Allocate memory and copy curbuf line into it.
 ///
 /// @param lnum the line to copy