vim-patch:8.2.1255: cannot use a lambda with quickfix functions

Problem:    Cannot use a lambda with quickfix functions.
Solution:   Add support for lambda. (Yegappan Lakshmanan, closes vim/vim#6499)
https://github.com/vim/vim/commit/d43906d2e5969288f239df851f5ad7b1dc2c7251

9 files changed, 232 insertions, 51 deletions

diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 9f44c016f0..bf7f2b21de 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -7879,7 +7879,8 @@ setqflist({list} [, {action}[, {what}]])		*setqflist()*
 				the last quickfix list.
 		    quickfixtextfunc
 				function to get the text to display in the
-				quickfix window.  Refer to
+				quickfix window.  The value can be the name of
+				a function or a funcref or a lambda.  Refer to
 				|quickfix-window-function| for an explanation
 				of how to write the function and an example.
 		    title	quickfix list title text. See |quickfix-title|
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index cc9696e536..af65241bbf 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -4607,7 +4607,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	customize the information displayed in the quickfix or location window
 	for each entry in the corresponding quickfix or location list.  See
 	|quickfix-window-function| for an explanation of how to write the
-	function and an example.
+	function and an example. The value can be the name of a function or a
+	lambda.
 
 	This option cannot be set from a |modeline| or in the |sandbox|, for
 	security reasons.
diff --git a/runtime/doc/quickfix.txt b/runtime/doc/quickfix.txt
index ebc7e2a1b4..563fb0c962 100644
--- a/runtime/doc/quickfix.txt
+++ b/runtime/doc/quickfix.txt
@@ -1919,7 +1919,10 @@ The function should return a single line of text to display in the quickfix
 window for each entry from start_idx to end_idx. The function can obtain
 information about the entries using the |getqflist()| function and specifying
 the quickfix list identifier "id". For a location list, getloclist() function
-can be used with the 'winid' argument.
+can be used with the 'winid' argument. If an empty list is returned, then the
+default format is used to display all the entries. If an item in the returned
+list is an empty string, then the default format is used to display the
+corresponding entry.
 
 If a quickfix or location list specific customization is needed, then the
 'quickfixtextfunc' attribute of the list can be set using the |setqflist()| or
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 7e462e568b..1b78147ec2 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -7200,12 +7200,15 @@ bool callback_from_typval(Callback *const callback, typval_T *const arg)
     r = FAIL;
   } else if (arg->v_type == VAR_FUNC || arg->v_type == VAR_STRING) {
     char_u *name = arg->vval.v_string;
-    if (name != NULL) {
+    if (name == NULL) {
+      r = FAIL;
+    } else if (*name == NUL) {
+      callback->type = kCallbackNone;
+      callback->data.funcref = NULL;
+    } else {
       func_ref(name);
       callback->data.funcref = vim_strsave(name);
       callback->type = kCallbackFuncref;
-    } else {
-      r = FAIL;
     }
   } else if (nlua_is_table_from_lua(arg)) {
     char_u *name = nlua_register_table_as_callable(arg);
@@ -7216,8 +7219,10 @@ bool callback_from_typval(Callback *const callback, typval_T *const arg)
     } else {
       r = FAIL;
     }
-  } else if (arg->v_type == VAR_NUMBER && arg->vval.v_number == 0) {
+  } else if (arg->v_type == VAR_SPECIAL
+             || (arg->v_type == VAR_NUMBER && arg->vval.v_number == 0)) {
     callback->type = kCallbackNone;
+    callback->data.funcref = NULL;
   } else {
     r = FAIL;
   }
diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index 4118ec407c..4275ff7c61 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -1162,20 +1162,48 @@ void callback_free(Callback *callback)
     }
   }
   callback->type = kCallbackNone;
+  callback->data.funcref = NULL;
 }
 
 /// Copy a callback into a typval_T.
 void callback_put(Callback *cb, typval_T *tv)
   FUNC_ATTR_NONNULL_ALL
 {
-  if (cb->type == kCallbackPartial) {
-    tv->v_type = VAR_PARTIAL;
-    tv->vval.v_partial = cb->data.partial;
-    cb->data.partial->pt_refcount++;
-  } else if (cb->type == kCallbackFuncref) {
-    tv->v_type = VAR_FUNC;
-    tv->vval.v_string = vim_strsave(cb->data.funcref);
-    func_ref(cb->data.funcref);
+  switch (cb->type) {
+    case kCallbackPartial:
+      tv->v_type = VAR_PARTIAL;
+      tv->vval.v_partial = cb->data.partial;
+      cb->data.partial->pt_refcount++;
+      break;
+    case kCallbackFuncref:
+      tv->v_type = VAR_FUNC;
+      tv->vval.v_string = vim_strsave(cb->data.funcref);
+      func_ref(cb->data.funcref);
+      break;
+    default:
+      tv->v_type = VAR_SPECIAL;
+      tv->vval.v_special = kSpecialVarNull;
+      break;
+  }
+}
+
+// Copy callback from "src" to "dest", incrementing the refcounts.
+void callback_copy(Callback *dest, Callback *src)
+  FUNC_ATTR_NONNULL_ALL
+{
+  dest->type = src->type;
+  switch (src->type) {
+    case kCallbackPartial:
+      dest->data.partial = src->data.partial;
+      dest->data.partial->pt_refcount++;
+      break;
+    case kCallbackFuncref:
+      dest->data.funcref = vim_strsave(src->data.funcref);
+      func_ref(src->data.funcref);
+      break;
+    default:
+      dest->data.funcref = NULL;
+      break;
   }
 }
 
diff --git a/src/nvim/eval/typval.h b/src/nvim/eval/typval.h
index 2b4612016b..050b84efec 100644
--- a/src/nvim/eval/typval.h
+++ b/src/nvim/eval/typval.h
@@ -120,7 +120,7 @@ typedef enum {
   VAR_DICT,         ///< Dictionary, .v_dict is used.
   VAR_FLOAT,        ///< Floating-point value, .v_float is used.
   VAR_BOOL,         ///< true, false
-  VAR_SPECIAL,      ///< Special value (true, false, null), .v_special
+  VAR_SPECIAL,      ///< Special value (null), .v_special
                     ///< is used.
   VAR_PARTIAL,      ///< Partial, .v_partial is used.
 } VarType;
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 57b8fe1a2e..f57abe89cc 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -85,6 +85,7 @@
 #include "nvim/api/private/helpers.h"
 #include "nvim/os/input.h"
 #include "nvim/os/lang.h"
+#include "nvim/quickfix.h"
 
 /*
  * The options that are local to a window or buffer have "indir" set to one of
@@ -3182,6 +3183,10 @@ ambw_end:
         }
       }
     }
+  } else if (varp == &p_qftf) {
+    if (!qf_process_qftf_option()) {
+      errmsg = e_invarg;
+    }
   } else {
     // Options that are a list of flags.
     p = NULL;
diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index 1a9bbe26f0..508257d5b1 100644
--- a/src/nvim/quickfix.c
+++ b/src/nvim/quickfix.c
@@ -100,7 +100,7 @@ typedef struct qf_list_S {
   char_u      *qf_title;        ///< title derived from the command that created
                                 ///< the error list or set by setqflist
   typval_T    *qf_ctx;          ///< context set by setqflist/setloclist
-  char_u      *qf_qftf;         ///< 'quickfixtextfunc' setting for this list
+  Callback  qftf_cb;            ///< 'quickfixtextfunc' callback function
 
   struct dir_stack_T *qf_dir_stack;
   char_u *qf_directory;
@@ -541,6 +541,9 @@ static int efm_to_regpat(const char_u *efm, int len, efm_T *fmt_ptr,
 
 static efm_T *fmt_start = NULL;  // cached across qf_parse_line() calls
 
+// callback function for 'quickfixtextfunc'
+static Callback qftf_cb;
+
 static void free_efm_list(efm_T **efm_first)
 {
   for (efm_T *efm_ptr = *efm_first; efm_ptr != NULL; efm_ptr = *efm_first) {
@@ -1978,7 +1981,7 @@ static int copy_loclist_entries(const qf_list_T *from_qfl, qf_list_T *to_qfl)
 }
 
 /// Copy the specified location list 'from_qfl' to 'to_qfl'.
-static int copy_loclist(const qf_list_T *from_qfl, qf_list_T *to_qfl)
+static int copy_loclist(qf_list_T *from_qfl, qf_list_T *to_qfl)
   FUNC_ATTR_NONNULL_ALL
 {
   // Some of the fields are populated by qf_add_entry()
@@ -2000,11 +2003,7 @@ static int copy_loclist(const qf_list_T *from_qfl, qf_list_T *to_qfl)
   } else {
     to_qfl->qf_ctx = NULL;
   }
-  if (from_qfl->qf_qftf != NULL) {
-    to_qfl->qf_qftf = vim_strsave(from_qfl->qf_qftf);
-  } else {
-    to_qfl->qf_qftf = NULL;
-  }
+  callback_copy(&to_qfl->qftf_cb, &from_qfl->qftf_cb);
 
   if (from_qfl->qf_count) {
     if (copy_loclist_entries(from_qfl, to_qfl) == FAIL) {
@@ -3385,7 +3384,7 @@ static void qf_free(qf_list_T *qfl)
   XFREE_CLEAR(qfl->qf_title);
   tv_free(qfl->qf_ctx);
   qfl->qf_ctx = NULL;
-  XFREE_CLEAR(qfl->qf_qftf);
+  callback_free(&qfl->qftf_cb);
   qfl->qf_id = 0;
   qfl->qf_changedtick = 0L;
 }
@@ -3860,6 +3859,41 @@ static buf_T *qf_find_buf(qf_info_T *qi)
   return NULL;
 }
 
+// Process the 'quickfixtextfunc' option value.
+bool qf_process_qftf_option(void)
+{
+  typval_T *tv;
+  Callback cb;
+
+  if (p_qftf == NULL || *p_qftf == NUL) {
+    callback_free(&qftf_cb);
+    return true;
+  }
+
+  if (*p_qftf == '{') {
+    // Lambda expression
+    tv = eval_expr(p_qftf);
+    if (tv == NULL) {
+      return false;
+    }
+  } else {
+    // treat everything else as a function name string
+    tv = xcalloc(1, sizeof(*tv));
+    tv->v_type = VAR_STRING;
+    tv->vval.v_string = vim_strsave(p_qftf);
+  }
+
+  if (!callback_from_typval(&cb, tv)) {
+    tv_free(tv);
+    return false;
+  }
+
+  callback_free(&qftf_cb);
+  qftf_cb = cb;
+  tv_free(tv);
+  return true;
+}
+
 /// Update the w:quickfix_title variable in the quickfix/location list window in
 /// all the tab pages.
 static void qf_update_win_titlevar(qf_info_T *qi)
@@ -3928,7 +3962,9 @@ static int qf_buf_add_line(qf_list_T *qfl, buf_T *buf, linenr_T lnum,
   int len;
   buf_T *errbuf;
 
-  if (qftf_str != NULL) {
+  // If the 'quickfixtextfunc' function returned an non-empty custom string
+  // for this entry, then use it.
+  if (qftf_str != NULL && *qftf_str != NUL) {
     STRLCPY(IObuff, qftf_str, IOSIZE);
   } else {
     if (qfp->qf_module != NULL) {
@@ -3997,22 +4033,25 @@ static int qf_buf_add_line(qf_list_T *qfl, buf_T *buf, linenr_T lnum,
   return OK;
 }
 
+// Call the 'quickfixtextfunc' function to get the list of lines to display in
+// the quickfix window for the entries 'start_idx' to 'end_idx'.
 static list_T *call_qftf_func(qf_list_T *qfl,
                               int qf_winid,
                               long start_idx,
                               long end_idx)
 {
-  char_u *qftf = p_qftf;
+  Callback *cb = &qftf_cb;
   list_T *qftf_list = NULL;
 
   // If 'quickfixtextfunc' is set, then use the user-supplied function to get
   // the text to display. Use the local value of 'quickfixtextfunc' if it is
   // set.
-  if (qfl->qf_qftf != NULL) {
-    qftf = qfl->qf_qftf;
+  if (qfl->qftf_cb.type != kCallbackNone) {
+    cb = &qfl->qftf_cb;
   }
-  if (qftf != NULL && *qftf != NUL) {
+  if (cb != NULL && cb->type != kCallbackNone) {
     typval_T args[1];
+    typval_T rettv;
 
     // create the dict argument
     dict_T *const dict = tv_dict_alloc_lock(VAR_FIXED);
@@ -4026,8 +4065,16 @@ static list_T *call_qftf_func(qf_list_T *qfl,
     args[0].v_type = VAR_DICT;
     args[0].vval.v_dict = dict;
 
-    qftf_list = call_func_retlist(qftf, 1, args);
-    dict->dv_refcount--;
+    qftf_list = NULL;
+
+    if (callback_call(cb, 1, args, &rettv)) {
+      if (rettv.v_type == VAR_LIST) {
+        qftf_list = rettv.vval.v_list;
+        tv_list_ref(qftf_list);
+      }
+      tv_clear(&rettv);
+    }
+    tv_dict_unref(dict);
   }
 
   return qftf_list;
@@ -4064,6 +4111,7 @@ static void qf_fill_buffer(qf_list_T *qfl, buf_T *buf, qfline_T *old_last,
   if (qfl != NULL) {
      char_u dirname[MAXPATHL];
      int prev_bufnr = -1;
+     bool invalid_val = false;
 
      *dirname = NUL;
 
@@ -4086,10 +4134,15 @@ static void qf_fill_buffer(qf_list_T *qfl, buf_T *buf, qfline_T *old_last,
     while (lnum < qfl->qf_count) {
       char_u *qftf_str = NULL;
 
-        if (qftf_li != NULL) {
-          // Use the text supplied by the user defined function
-          qftf_str = (char_u *)tv_get_string_chk(TV_LIST_ITEM_TV(qftf_li));
+      // Use the text supplied by the user defined function (if any).
+      // If the returned value is not string, then ignore the rest
+      // of the returned values and use the default.
+      if (qftf_li != NULL && !invalid_val) {
+        qftf_str = (char_u *)tv_get_string_chk(TV_LIST_ITEM_TV(qftf_li));
+        if (qftf_str == NULL) {
+          invalid_val = true;
         }
+      }
 
       if (qf_buf_add_line(qfl, buf, lnum, qfp, dirname, qftf_str,
                           prev_bufnr != qfp->qf_fnum) == FAIL) {
@@ -5796,7 +5849,9 @@ enum {
   QF_GETLIST_SIZE = 0x80,
   QF_GETLIST_TICK = 0x100,
   QF_GETLIST_FILEWINID = 0x200,
-  QF_GETLIST_ALL = 0x3FF,
+  QF_GETLIST_QFBUFNR = 0x400,
+  QF_GETLIST_QFTF = 0x800,
+  QF_GETLIST_ALL = 0xFFF,
 };
 
 /// Parse text from 'di' and return the quickfix list items.
@@ -5894,6 +5949,9 @@ static int qf_getprop_keys2flags(const dict_T *what, bool loclist)
   if (loclist && tv_dict_find(what, S_LEN("filewinid")) != NULL) {
     flags |= QF_GETLIST_FILEWINID;
   }
+  if (tv_dict_find(what, S_LEN("quickfixtextfunc")) != NULL) {
+    flags |= QF_GETLIST_QFTF;
+  }
 
   return flags;
 }
@@ -5985,6 +6043,9 @@ static int qf_getprop_defaults(qf_info_T *qi,
   if ((status == OK) && locstack && (flags & QF_GETLIST_FILEWINID)) {
     status = tv_dict_add_nr(retdict, S_LEN("filewinid"), 0);
   }
+  if ((status == OK) && (flags & QF_GETLIST_QFTF)) {
+    status = tv_dict_add_str(retdict, S_LEN("quickfixtextfunc"), "");
+  }
 
   return status;
 }
@@ -6060,6 +6121,26 @@ static int qf_getprop_idx(qf_list_T *qfl, int eidx, dict_T *retdict)
   return tv_dict_add_nr(retdict, S_LEN("idx"), eidx);
 }
 
+/// Return the 'quickfixtextfunc' function of a quickfix/location list
+/// @return OK or FAIL
+static int qf_getprop_qftf(qf_list_T *qfl, dict_T *retdict)
+  FUNC_ATTR_NONNULL_ALL
+{
+  int status;
+
+  if (qfl->qftf_cb.type != kCallbackNone) {
+    typval_T tv;
+
+    callback_put(&qfl->qftf_cb, &tv);
+    status = tv_dict_add_tv(retdict, S_LEN("quickfixtextfunc"), &tv);
+    tv_clear(&tv);
+  } else {
+    status = tv_dict_add_str(retdict, S_LEN("quickfixtextfunc"), "");
+  }
+
+  return status;
+}
+
 /// Return quickfix/location list details (title) as a dictionary.
 /// 'what' contains the details to return. If 'list_idx' is -1,
 /// then current list is used. Otherwise the specified list is used.
@@ -6133,19 +6214,25 @@ int qf_get_properties(win_T *wp, dict_T *what, dict_T *retdict)
   if ((status == OK) && (wp != NULL) && (flags & QF_GETLIST_FILEWINID)) {
     status = qf_getprop_filewinid(wp, qi, retdict);
   }
+  if ((status == OK) && (flags & QF_GETLIST_QFTF)) {
+    status = qf_getprop_qftf(qfl, retdict);
+  }
 
   return status;
 }
 
 /// Set the current index in the specified quickfix list
-static int qf_setprop_qftf(qf_info_T *qi, qf_list_T *qfl,
-                           dictitem_T *di)
+/// @return OK
+static int qf_setprop_qftf(qf_list_T *qfl, dictitem_T *di)
+  FUNC_ATTR_NONNULL_ALL
 {
-    XFREE_CLEAR(qfl->qf_qftf);
-    if (di->di_tv.v_type == VAR_STRING && di->di_tv.vval.v_string != NULL) {
-      qfl->qf_qftf = vim_strsave(di->di_tv.vval.v_string);
-    }
-    return OK;
+  Callback cb;
+
+  callback_free(&qfl->qftf_cb);
+  if (callback_from_typval(&cb, &di->di_tv)) {
+    qfl->qftf_cb = cb;
+  }
+  return OK;
 }
 
 /// Add a new quickfix entry to list at 'qf_idx' in the stack 'qi' from the
@@ -6514,7 +6601,7 @@ static int qf_set_properties(qf_info_T *qi, const dict_T *what, int action,
     retval = qf_setprop_curidx(qi, qfl, di);
   }
   if ((di = tv_dict_find(what, S_LEN("quickfixtextfunc"))) != NULL) {
-    retval = qf_setprop_qftf(qi, qfl, di);
+    retval = qf_setprop_qftf(qfl, di);
   }
 
   if (newlist || retval == OK) {
diff --git a/src/nvim/testdir/test_quickfix.vim b/src/nvim/testdir/test_quickfix.vim
index 14240f0d5f..c63613ab1b 100644
--- a/src/nvim/testdir/test_quickfix.vim
+++ b/src/nvim/testdir/test_quickfix.vim
@@ -3483,12 +3483,13 @@ func Xgetlist_empty_tests(cchar)
   if a:cchar == 'c'
     call assert_equal({'context' : '', 'id' : 0, 'idx' : 0,
 		  \ 'items' : [], 'nr' : 0, 'size' : 0,
-		  \ 'title' : '', 'winid' : 0, 'changedtick': 0},
-		  \ g:Xgetlist({'all' : 0}))
+		  \ 'title' : '', 'winid' : 0, 'changedtick': 0,
+                  \ 'quickfixtextfunc' : ''}, g:Xgetlist({'all' : 0}))
   else
     call assert_equal({'context' : '', 'id' : 0, 'idx' : 0,
 		\ 'items' : [], 'nr' : 0, 'size' : 0, 'title' : '',
-		\ 'winid' : 0, 'changedtick': 0, 'filewinid' : 0},
+		\ 'winid' : 0, 'changedtick': 0, 'filewinid' : 0,
+		\ 'quickfixtextfunc' : ''},
 		\ g:Xgetlist({'all' : 0}))
   endif
 
@@ -3526,11 +3527,13 @@ func Xgetlist_empty_tests(cchar)
   if a:cchar == 'c'
     call assert_equal({'context' : '', 'id' : 0, 'idx' : 0, 'items' : [],
 		\ 'nr' : 0, 'size' : 0, 'title' : '', 'winid' : 0,
+		\ 'quickfixtextfunc' : '',
 		\ 'changedtick' : 0}, g:Xgetlist({'id' : qfid, 'all' : 0}))
   else
     call assert_equal({'context' : '', 'id' : 0, 'idx' : 0, 'items' : [],
 		\ 'nr' : 0, 'size' : 0, 'title' : '', 'winid' : 0,
-		\ 'changedtick' : 0, 'filewinid' : 0},
+		\ 'changedtick' : 0, 'filewinid' : 0,
+                \ 'quickfixtextfunc' : ''},
 		\ g:Xgetlist({'id' : qfid, 'all' : 0}))
   endif
 
@@ -3547,12 +3550,13 @@ func Xgetlist_empty_tests(cchar)
   if a:cchar == 'c'
     call assert_equal({'context' : '', 'id' : 0, 'idx' : 0, 'items' : [],
 		\ 'nr' : 0, 'size' : 0, 'title' : '', 'winid' : 0,
-		\ 'changedtick' : 0}, g:Xgetlist({'nr' : 5, 'all' : 0}))
+		\ 'changedtick' : 0,
+                \ 'quickfixtextfunc' : ''}, g:Xgetlist({'nr' : 5, 'all' : 0}))
   else
     call assert_equal({'context' : '', 'id' : 0, 'idx' : 0, 'items' : [],
 		\ 'nr' : 0, 'size' : 0, 'title' : '', 'winid' : 0,
-		\ 'changedtick' : 0, 'filewinid' : 0},
-		\ g:Xgetlist({'nr' : 5, 'all' : 0}))
+		\ 'changedtick' : 0, 'filewinid' : 0,
+                \ 'quickfixtextfunc' : ''}, g:Xgetlist({'nr' : 5, 'all' : 0}))
   endif
 endfunc
 
@@ -4994,6 +4998,9 @@ func Xtest_qftextfunc(cchar)
 
   set efm=%f:%l:%c:%m
   set quickfixtextfunc=Tqfexpr
+  call assert_equal('Tqfexpr', &quickfixtextfunc)
+  call assert_equal('',
+        \ g:Xgetlist({'quickfixtextfunc' : 1}).quickfixtextfunc)
   Xexpr ['F1:10:2:green', 'F1:20:4:blue']
   Xwindow
   call assert_equal('F1-L10C2-green', getline(1))
@@ -5030,12 +5037,15 @@ func Xtest_qftextfunc(cchar)
   call assert_equal('Line 10, Col 2', getline(1))
   call assert_equal('Line 20, Col 4', getline(2))
   Xclose
+  call assert_equal(function('PerQfText'),
+        \ g:Xgetlist({'quickfixtextfunc' : 1}).quickfixtextfunc)
   " Add entries to the list when the quickfix buffer is hidden
   Xaddexpr ['F1:30:6:red']
   Xwindow
   call assert_equal('Line 30, Col 6', getline(3))
   Xclose
   call g:Xsetlist([], 'r', {'quickfixtextfunc' : ''})
+  call assert_equal('', g:Xgetlist({'quickfixtextfunc' : 1}).quickfixtextfunc)
   set quickfixtextfunc&
   delfunc PerQfText
 
@@ -5074,12 +5084,53 @@ func Xtest_qftextfunc(cchar)
   "                                                                 \ 'E730:')
   Xexpr ['F1:10:2:green', 'F1:20:4:blue', 'F1:30:6:red']
   call assert_fails('Xwindow', 'E730:')
-  call assert_equal(['one', 'F1|20 col 4| blue', 'two'], getline(1, '$'))
+  call assert_equal(['one', 'F1|20 col 4| blue', 'F1|30 col 6| red'],
+        \ getline(1, '$'))
   Xclose
 
   set quickfixtextfunc&
   delfunc Xqftext
   delfunc Xqftext2
+
+  " set the global option to a lambda function
+  set quickfixtextfunc={d\ ->\ map(g:Xgetlist({'id'\ :\ d.id,\ 'items'\ :\ 1}).items[d.start_idx-1:d.end_idx-1],\ 'v:val.text')}
+  Xexpr ['F1:10:2:green', 'F1:20:4:blue']
+  Xwindow
+  call assert_equal(['green', 'blue'], getline(1, '$'))
+  Xclose
+  call assert_equal("{d -> map(g:Xgetlist({'id' : d.id, 'items' : 1}).items[d.start_idx-1:d.end_idx-1], 'v:val.text')}", &quickfixtextfunc)
+  set quickfixtextfunc&
+
+  " use a lambda function that returns an empty list
+  set quickfixtextfunc={d\ ->\ []}
+  Xexpr ['F1:10:2:green', 'F1:20:4:blue']
+  Xwindow
+  call assert_equal(['F1|10 col 2| green', 'F1|20 col 4| blue'],
+        \ getline(1, '$'))
+  Xclose
+  set quickfixtextfunc&
+
+  " use a lambda function that returns a list with empty strings
+  set quickfixtextfunc={d\ ->\ ['',\ '']}
+  Xexpr ['F1:10:2:green', 'F1:20:4:blue']
+  Xwindow
+  call assert_equal(['F1|10 col 2| green', 'F1|20 col 4| blue'],
+        \ getline(1, '$'))
+  Xclose
+  set quickfixtextfunc&
+
+  " set the per-quickfix list text function to a lambda function
+  call g:Xsetlist([], ' ',
+        \ {'quickfixtextfunc' :
+        \   {d -> map(g:Xgetlist({'id' : d.id, 'items' : 1}).items[d.start_idx-1:d.end_idx-1],
+        \ "'Line ' .. v:val.lnum .. ', Col ' .. v:val.col")}})
+  Xaddexpr ['F1:10:2:green', 'F1:20:4:blue']
+  Xwindow
+  call assert_equal('Line 10, Col 2', getline(1))
+  call assert_equal('Line 20, Col 4', getline(2))
+  Xclose
+  call assert_match("function('<lambda>\\d\\+')", string(g:Xgetlist({'quickfixtextfunc' : 1}).quickfixtextfunc))
+  call g:Xsetlist([], 'f')
 endfunc
 
 func Test_qftextfunc()