vim-patch:8.2.0077: settagstack() cannot truncate at current index

Problem:    settagstack() cannot truncate at current index.
Solution:   Add the "t" action. (Yegappan Lakshmanan, closes vim/vim#5417)
https://github.com/vim/vim/commit/271fa08a35b8d320d3a40db4ddae83b698fdd4fb

1 files changed, 26 insertions, 8 deletions

diff --git a/src/nvim/tag.c b/src/nvim/tag.c
index a412ed0276..07f29977aa 100644
--- a/src/nvim/tag.c
+++ b/src/nvim/tag.c
@@ -3378,11 +3378,15 @@ static void tagstack_set_curidx(win_T *wp, int curidx)
 }
 
 // Set the tag stack entries of the specified window.
-// 'action' is set to either 'a' for append or 'r' for replace.
-int set_tagstack(win_T *wp, dict_T *d, int action)
+// 'action' is set to one of:
+//    'a' for append
+//    'r' for replace
+//    't' for truncate
+int set_tagstack(win_T *wp, const dict_T *d, int action)
+  FUNC_ATTR_NONNULL_ARG(1)
 {
   dictitem_T *di;
-  list_T *l;
+  list_T *l = NULL;
 
   // not allowed to alter the tag stack entries from inside tagfunc
   if (tfu_in_use) {
@@ -3395,16 +3399,30 @@ int set_tagstack(win_T *wp, dict_T *d, int action)
       return FAIL;
     }
     l = di->di_tv.vval.v_list;
+  }
 
-    if (action == 'r') {
+  if ((di = tv_dict_find(d, "curidx", -1)) != NULL) {
+    tagstack_set_curidx(wp, (int)tv_get_number(&di->di_tv) - 1);
+  }
+  if (action == 't') {  // truncate the stack
+    taggy_T *const tagstack = wp->w_tagstack;
+    const int tagstackidx = wp->w_tagstackidx;
+    int tagstacklen = wp->w_tagstacklen;
+    // delete all the tag stack entries above the current entry
+    while (tagstackidx < tagstacklen) {
+      tagstack_clear_entry(&tagstack[--tagstacklen]);
+    }
+    wp->w_tagstacklen = tagstacklen;
+  }
+
+  if (l != NULL) {
+    if (action == 'r') {  // replace the stack
       tagstack_clear(wp);
     }
 
     tagstack_push_items(wp, l);
-  }
-
-  if ((di = tv_dict_find(d, "curidx", -1)) != NULL) {
-    tagstack_set_curidx(wp, (int)tv_get_number(&di->di_tv) - 1);
+    // set the current index after the last entry
+    wp->w_tagstackidx = wp->w_tagstacklen;
   }
 
   return OK;