patch 8.2.3788: lambda for option that is a function may be freedv8.2.3788

Problem:    Lambda for option that is a function may be garbage collected.
Solution:   Set a reference in the funcref. (Yegappan Lakshmanan,
            closes #9330)

19 files changed, 1091 insertions, 898 deletions

diff --git a/src/eval.c b/src/eval.c
index e2aa41b34f..64381f0f3d 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -4516,6 +4516,18 @@ garbage_collect(int testing)
     // callbacks in buffers
     abort = abort || set_ref_in_buffers(copyID);
 
+    // 'completefunc', 'omnifunc' and 'thesaurusfunc' callbacks
+    abort = abort || set_ref_in_insexpand_funcs(copyID);
+
+    // 'operatorfunc' callback
+    abort = abort || set_ref_in_opfunc(copyID);
+
+    // 'tagfunc' callback
+    abort = abort || set_ref_in_tagfunc(copyID);
+
+    // 'imactivatefunc' and 'imstatusfunc' callbacks
+    abort = abort || set_ref_in_im_funcs(copyID);
+
 #ifdef FEAT_LUA
     abort = abort || set_ref_in_lua(copyID);
 #endif
@@ -4744,6 +4756,22 @@ set_ref_in_list_items(list_T *l, int copyID, ht_stack_T **ht_stack)
 }
 
 /*
+ * Mark the partial in callback 'cb' with "copyID".
+ */
+    int
+set_ref_in_callback(callback_T *cb, int copyID)
+{
+    typval_T tv;
+
+    if (cb->cb_name == NULL || *cb->cb_name == NUL || cb->cb_partial == NULL)
+	return FALSE;
+
+    tv.v_type = VAR_PARTIAL;
+    tv.vval.v_partial = cb->cb_partial;
+    return set_ref_in_item(&tv, copyID, NULL, NULL);
+}
+
+/*
  * Mark all lists and dicts referenced through typval "tv" with "copyID".
  * "list_stack" is used to add lists to be marked.  Can be NULL.
  * "ht_stack" is used to add hashtabs to be marked.  Can be NULL.
diff --git a/src/evalbuffer.c b/src/evalbuffer.c
index 77acf8fe90..ba16436ded 100644
--- a/src/evalbuffer.c
+++ b/src/evalbuffer.c
@@ -26,31 +26,25 @@ set_ref_in_buffers(int copyID)
     FOR_ALL_BUFFERS(bp)
     {
 	listener_T *lnr;
-	typval_T tv;
 
 	for (lnr = bp->b_listener; !abort && lnr != NULL; lnr = lnr->lr_next)
-	{
-	    if (lnr->lr_callback.cb_partial != NULL)
-	    {
-		tv.v_type = VAR_PARTIAL;
-		tv.vval.v_partial = lnr->lr_callback.cb_partial;
-		abort = abort || set_ref_in_item(&tv, copyID, NULL, NULL);
-	    }
-	}
+	    abort = abort || set_ref_in_callback(&lnr->lr_callback, copyID);
 # ifdef FEAT_JOB_CHANNEL
-	if (!abort && bp->b_prompt_callback.cb_partial != NULL)
-	{
-	    tv.v_type = VAR_PARTIAL;
-	    tv.vval.v_partial = bp->b_prompt_callback.cb_partial;
-	    abort = abort || set_ref_in_item(&tv, copyID, NULL, NULL);
-	}
-	if (!abort && bp->b_prompt_interrupt.cb_partial != NULL)
-	{
-	    tv.v_type = VAR_PARTIAL;
-	    tv.vval.v_partial = bp->b_prompt_interrupt.cb_partial;
-	    abort = abort || set_ref_in_item(&tv, copyID, NULL, NULL);
-	}
+	if (!abort)
+	    abort = abort || set_ref_in_callback(&bp->b_prompt_callback, copyID);
+	if (!abort)
+	    abort = abort || set_ref_in_callback(&bp->b_prompt_interrupt, copyID);
 # endif
+#ifdef FEAT_COMPL_FUNC
+	if (!abort)
+	    abort = abort || set_ref_in_callback(&bp->b_cfu_cb, copyID);
+	if (!abort)
+	    abort = abort || set_ref_in_callback(&bp->b_ofu_cb, copyID);
+	if (!abort)
+	    abort = abort || set_ref_in_callback(&bp->b_tsrfu_cb, copyID);
+#endif
+	if (!abort)
+	    abort = abort || set_ref_in_callback(&bp->b_tfu_cb, copyID);
 	if (abort)
 	    break;
     }
diff --git a/src/evalvars.c b/src/evalvars.c
index 041025967a..a12b9bd23b 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -1395,7 +1395,6 @@ ex_let_option(
 	char_u	    *tofree = NULL;
 	char_u	    numbuf[NUMBUFLEN];
 
-
 	c1 = *p;
 	*p = NUL;
 
diff --git a/src/gui_xim.c b/src/gui_xim.c
index 6d72ef1d66..4bd1a2eedf 100644
--- a/src/gui_xim.c
+++ b/src/gui_xim.c
@@ -117,7 +117,7 @@ call_imstatusfunc(void)
     void
 free_xim_stuff(void)
 {
-#if defined(FEAT_EVAL) && \
+# if defined(FEAT_EVAL) && \
     (defined(FEAT_XIM) || defined(IME_WITHOUT_XIM) || defined(VIMDLL))
     free_callback(&imaf_cb);
     free_callback(&imsf_cb);
@@ -125,6 +125,24 @@ free_xim_stuff(void)
 }
 #endif
 
+/*
+ * Mark the global 'imactivatefunc' and 'imstatusfunc' callbacks with 'copyID'
+ * so that they are not garbage collected.
+ */
+    int
+set_ref_in_im_funcs(int copyID UNUSED)
+{
+    int abort = FALSE;
+
+#if defined(FEAT_EVAL) && \
+    (defined(FEAT_XIM) || defined(IME_WITHOUT_XIM) || defined(VIMDLL))
+    abort = set_ref_in_callback(&imaf_cb, copyID);
+    abort = abort || set_ref_in_callback(&imsf_cb, copyID);
+#endif
+
+    return abort;
+}
+
 
 #if defined(FEAT_XIM) || defined(PROTO)
 
diff --git a/src/insexpand.c b/src/insexpand.c
index 8c09841f00..bc490b9648 100644
--- a/src/insexpand.c
+++ b/src/insexpand.c
@@ -2341,6 +2341,21 @@ set_thesaurusfunc_option(void)
     return retval;
 }
 
+/*
+ * Mark the global 'completefunc' 'omnifunc' and 'thesaurusfunc' callbacks with
+ * 'copyID' so that they are not garbage collected.
+ */
+    int
+set_ref_in_insexpand_funcs(int copyID)
+{
+    int abort = FALSE;
+
+    abort = set_ref_in_callback(&cfu_cb, copyID);
+    abort = abort || set_ref_in_callback(&ofu_cb, copyID);
+    abort = abort || set_ref_in_callback(&tsrfu_cb, copyID);
+
+    return abort;
+}
 
 /*
  * Get the user-defined completion function name for completion 'type'
diff --git a/src/ops.c b/src/ops.c
index a1afc258e1..f58d6f8d1d 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -3341,13 +3341,29 @@ set_operatorfunc_option(void)
     void
 free_operatorfunc_option(void)
 {
-#  ifdef FEAT_EVAL
+# ifdef FEAT_EVAL
     free_callback(&opfunc_cb);
-#  endif
+# endif
 }
 #endif
 
 /*
+ * Mark the global 'operatorfunc' callback with 'copyID' so that it is not
+ * garbage collected.
+ */
+    int
+set_ref_in_opfunc(int copyID UNUSED)
+{
+    int abort = FALSE;
+
+#ifdef FEAT_EVAL
+    abort = set_ref_in_callback(&opfunc_cb, copyID);
+#endif
+
+    return abort;
+}
+
+/*
  * Handle the "g@" operator: call 'operatorfunc'.
  */
     static void
diff --git a/src/proto/eval.pro b/src/proto/eval.pro
index 45b559de52..dc9c53b516 100644
--- a/src/proto/eval.pro
+++ b/src/proto/eval.pro
@@ -52,6 +52,7 @@ int set_ref_in_ht(hashtab_T *ht, int copyID, list_stack_T **list_stack);
 int set_ref_in_dict(dict_T *d, int copyID);
 int set_ref_in_list(list_T *ll, int copyID);
 int set_ref_in_list_items(list_T *l, int copyID, ht_stack_T **ht_stack);
+int set_ref_in_callback(callback_T *cb, int copyID);
 int set_ref_in_item(typval_T *tv, int copyID, ht_stack_T **ht_stack, list_stack_T **list_stack);
 char_u *echo_string_core(typval_T *tv, char_u **tofree, char_u *numbuf, int copyID, int echo_style, int restore_copyID, int composite_val);
 char_u *echo_string(typval_T *tv, char_u **tofree, char_u *numbuf, int copyID);
diff --git a/src/proto/gui_xim.pro b/src/proto/gui_xim.pro
index 60f30d7587..8c5c53a150 100644
--- a/src/proto/gui_xim.pro
+++ b/src/proto/gui_xim.pro
@@ -2,6 +2,7 @@
 int set_imactivatefunc_option(void);
 int set_imstatusfunc_option(void);
 void free_xim_stuff(void);
+int set_ref_in_im_funcs(int copyID);
 void im_set_active(int active);
 void xim_set_focus(int focus);
 void im_set_position(int row, int col);
diff --git a/src/proto/insexpand.pro b/src/proto/insexpand.pro
index d455a98fd7..6d975570d6 100644
--- a/src/proto/insexpand.pro
+++ b/src/proto/insexpand.pro
@@ -44,6 +44,7 @@ void set_buflocal_cfu_callback(buf_T *buf);
 int set_omnifunc_option(void);
 void set_buflocal_ofu_callback(buf_T *buf);
 int set_thesaurusfunc_option(void);
+int set_ref_in_insexpand_funcs(int copyID);
 callback_T *get_insert_callback(int type);
 void f_complete(typval_T *argvars, typval_T *rettv);
 void f_complete_add(typval_T *argvars, typval_T *rettv);
diff --git a/src/proto/ops.pro b/src/proto/ops.pro
index c46af05a04..1e89c4e99f 100644
--- a/src/proto/ops.pro
+++ b/src/proto/ops.pro
@@ -19,5 +19,6 @@ void clear_oparg(oparg_T *oap);
 void cursor_pos_info(dict_T *dict);
 int set_operatorfunc_option(void);
 void free_operatorfunc_option(void);
+int set_ref_in_opfunc(int copyID);
 void do_pending_operator(cmdarg_T *cap, int old_col, int gui_yank);
 /* vim: set ft=c : */
diff --git a/src/proto/tag.pro b/src/proto/tag.pro
index c8ef72101e..9820571874 100644
--- a/src/proto/tag.pro
+++ b/src/proto/tag.pro
@@ -1,6 +1,7 @@
 /* tag.c */
 int set_tagfunc_option(void);
 void free_tagfunc_option(void);
+int set_ref_in_tagfunc(int copyID);
 void set_buflocal_tfu_callback(buf_T *buf);
 int do_tag(char_u *tag, int type, int count, int forceit, int verbose);
 void tag_freematch(void);
diff --git a/src/quickfix.c b/src/quickfix.c
index c7abc8ec4a..eeee8068d3 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -7675,7 +7675,8 @@ set_errorlist(
 }
 
 /*
- * Mark the context as in use for all the lists in a quickfix stack.
+ * Mark the quickfix context and callback function as in use for all the lists
+ * in a quickfix stack.
  */
     static int
 mark_quickfix_ctx(qf_info_T *qi, int copyID)
@@ -7683,13 +7684,17 @@ mark_quickfix_ctx(qf_info_T *qi, int copyID)
     int		i;
     int		abort = FALSE;
     typval_T	*ctx;
+    callback_T	*cb;
 
     for (i = 0; i < LISTCOUNT && !abort; ++i)
     {
 	ctx = qi->qf_lists[i].qf_ctx;
 	if (ctx != NULL && ctx->v_type != VAR_NUMBER
 		&& ctx->v_type != VAR_STRING && ctx->v_type != VAR_FLOAT)
-	    abort = set_ref_in_item(ctx, copyID, NULL, NULL);
+	    abort = abort || set_ref_in_item(ctx, copyID, NULL, NULL);
+
+	cb = &qi->qf_lists[i].qftf_cb;
+	abort = abort || set_ref_in_callback(cb, copyID);
     }
 
     return abort;
@@ -7710,6 +7715,10 @@ set_ref_in_quickfix(int copyID)
     if (abort)
 	return abort;
 
+    abort = set_ref_in_callback(&qftf_cb, copyID);
+    if (abort)
+	return abort;
+
     FOR_ALL_TAB_WINDOWS(tp, win)
     {
 	if (win->w_llist != NULL)
diff --git a/src/tag.c b/src/tag.c
index 48a69d466c..85d1438881 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -133,15 +133,31 @@ set_tagfunc_option(void)
     return OK;
 }
 
-# if defined(EXITFREE) || defined(PROTO)
+#if defined(EXITFREE) || defined(PROTO)
     void
 free_tagfunc_option(void)
 {
-#  ifdef FEAT_EVAL
+# ifdef FEAT_EVAL
     free_callback(&tfu_cb);
-#  endif
-}
 # endif
+}
+#endif
+
+/*
+ * Mark the global 'tagfunc' callback with 'copyID' so that it is not garbage
+ * collected.
+ */
+    int
+set_ref_in_tagfunc(int copyID UNUSED)
+{
+    int	abort = FALSE;
+
+#ifdef FEAT_EVAL
+    abort = set_ref_in_callback(&tfu_cb, copyID);
+#endif
+
+    return abort;
+}
 
 /*
  * Copy the global 'tagfunc' callback function to the buffer-local 'tagfunc'
diff --git a/src/testdir/test_iminsert.vim b/src/testdir/test_iminsert.vim
index a53e6f36b4..860fb07ad3 100644
--- a/src/testdir/test_iminsert.vim
+++ b/src/testdir/test_iminsert.vim
@@ -119,83 +119,142 @@ func Test_imactivatefunc_imstatusfunc_callback()
     let g:IMstatusfunc_called += 1
     return 1
   endfunc
-  let g:IMactivatefunc_called = 0
-  let g:IMstatusfunc_called = 0
   set iminsert=2
 
-  " Test for using a function()
-  set imactivatefunc=function('IMactivatefunc1')
-  set imstatusfunc=function('IMstatusfunc1')
-  normal! i
+  let lines =<< trim END
+    LET g:IMactivatefunc_called = 0
+    LET g:IMstatusfunc_called = 0
 
-  " Using a funcref variable to set 'completefunc'
-  let Fn1 = function('IMactivatefunc1')
-  let &imactivatefunc = Fn1
-  let Fn2 = function('IMstatusfunc1')
-  let &imstatusfunc = Fn2
-  normal! i
+    #" Test for using a function()
+    set imactivatefunc=function('g:IMactivatefunc1')
+    set imstatusfunc=function('g:IMstatusfunc1')
+    normal! i
 
-  " Using a string(funcref variable) to set 'completefunc'
-  let &imactivatefunc = string(Fn1)
-  let &imstatusfunc = string(Fn2)
-  normal! i
+    #" Using a funcref variable to set 'completefunc'
+    VAR Fn1 = function('g:IMactivatefunc1')
+    LET &imactivatefunc = Fn1
+    VAR Fn2 = function('g:IMstatusfunc1')
+    LET &imstatusfunc = Fn2
+    normal! i
 
-  " Test for using a funcref()
-  set imactivatefunc=funcref('IMactivatefunc1')
-  set imstatusfunc=funcref('IMstatusfunc1')
-  normal! i
+    #" Using a string(funcref variable) to set 'completefunc'
+    LET &imactivatefunc = string(Fn1)
+    LET &imstatusfunc = string(Fn2)
+    normal! i
 
-  " Using a funcref variable to set 'imactivatefunc'
-  let Fn1 = funcref('IMactivatefunc1')
-  let &imactivatefunc = Fn1
-  let Fn2 = funcref('IMstatusfunc1')
-  let &imstatusfunc = Fn2
-  normal! i
+    #" Test for using a funcref()
+    set imactivatefunc=funcref('g:IMactivatefunc1')
+    set imstatusfunc=funcref('g:IMstatusfunc1')
+    normal! i
 
-  " Using a string(funcref variable) to set 'imactivatefunc'
-  let &imactivatefunc = string(Fn1)
-  let &imstatusfunc = string(Fn2)
-  normal! i
+    #" Using a funcref variable to set 'imactivatefunc'
+    LET Fn1 = funcref('g:IMactivatefunc1')
+    LET &imactivatefunc = Fn1
+    LET Fn2 = funcref('g:IMstatusfunc1')
+    LET &imstatusfunc = Fn2
+    normal! i
 
-  " Test for using a lambda function
-  set imactivatefunc={a\ ->\ IMactivatefunc1(a)}
-  set imstatusfunc={\ ->\ IMstatusfunc1()}
-  normal! i
+    #" Using a string(funcref variable) to set 'imactivatefunc'
+    LET &imactivatefunc = string(Fn1)
+    LET &imstatusfunc = string(Fn2)
+    normal! i
 
-  " Set 'imactivatefunc' and 'imstatusfunc' to a lambda expression
-  let &imactivatefunc = {a -> IMactivatefunc1(a)}
-  let &imstatusfunc = { -> IMstatusfunc1()}
-  normal! i
+    #" Test for using a lambda function
+    VAR optval = "LSTART a LMIDDLE IMactivatefunc1(a) LEND"
+    LET optval = substitute(optval, ' ', '\\ ', 'g')
+    exe "set imactivatefunc=" .. optval
+    LET optval = "LSTART LMIDDLE IMstatusfunc1() LEND"
+    LET optval = substitute(optval, ' ', '\\ ', 'g')
+    exe "set imstatusfunc=" .. optval
+    normal! i
 
-  " Set 'imactivatefunc' and 'imstatusfunc' to a string(lambda expression)
-  let &imactivatefunc = '{a -> IMactivatefunc1(a)}'
-  let &imstatusfunc = '{ -> IMstatusfunc1()}'
-  normal! i
+    #" Set 'imactivatefunc' and 'imstatusfunc' to a lambda expression
+    LET &imactivatefunc = LSTART a LMIDDLE IMactivatefunc1(a) LEND
+    LET &imstatusfunc = LSTART LMIDDLE IMstatusfunc1() LEND
+    normal! i
 
-  " Set 'imactivatefunc' 'imstatusfunc' to a variable with a lambda expression
-  let Lambda1 = {a -> IMactivatefunc1(a)}
-  let Lambda2 = { -> IMstatusfunc1()}
-  let &imactivatefunc = Lambda1
-  let &imstatusfunc = Lambda2
-  normal! i
+    #" Set 'imactivatefunc' and 'imstatusfunc' to a string(lambda expression)
+    LET &imactivatefunc = 'LSTART a LMIDDLE IMactivatefunc1(a) LEND'
+    LET &imstatusfunc = 'LSTART LMIDDLE IMstatusfunc1() LEND'
+    normal! i
 
-  " Set 'imactivatefunc' 'imstatusfunc' to a string(variable with a lambda
-  " expression)
-  let &imactivatefunc = string(Lambda1)
-  let &imstatusfunc = string(Lambda2)
-  normal! i
+    #" Set 'imactivatefunc' 'imstatusfunc' to a variable with a lambda
+    #" expression
+    VAR Lambda1 = LSTART a LMIDDLE IMactivatefunc1(a) LEND
+    VAR Lambda2 = LSTART LMIDDLE IMstatusfunc1() LEND
+    LET &imactivatefunc = Lambda1
+    LET &imstatusfunc = Lambda2
+    normal! i
+
+    #" Set 'imactivatefunc' 'imstatusfunc' to a string(variable with a lambda
+    #" expression)
+    LET &imactivatefunc = string(Lambda1)
+    LET &imstatusfunc = string(Lambda2)
+    normal! i
 
-  " Test for clearing the 'completefunc' option
-  set imactivatefunc='' imstatusfunc=''
-  set imactivatefunc& imstatusfunc&
+    #" Test for clearing the 'completefunc' option
+    set imactivatefunc='' imstatusfunc=''
+    set imactivatefunc& imstatusfunc&
+
+    set imactivatefunc=g:IMactivatefunc1
+    set imstatusfunc=g:IMstatusfunc1
+    call assert_fails("set imactivatefunc=function('abc')", "E700:")
+    call assert_fails("set imstatusfunc=function('abc')", "E700:")
+    call assert_fails("set imactivatefunc=funcref('abc')", "E700:")
+    call assert_fails("set imstatusfunc=funcref('abc')", "E700:")
+    call assert_fails("LET &imstatusfunc = function('abc')", "E700:")
+    call assert_fails("LET &imactivatefunc = function('abc')", "E700:")
+    normal! i
+
+    #" set 'imactivatefunc' and 'imstatusfunc' to a non-existing function
+    set imactivatefunc=IMactivatefunc1
+    set imstatusfunc=IMstatusfunc1
+    call assert_fails("set imactivatefunc=function('NonExistingFunc')", 'E700:')
+    call assert_fails("set imstatusfunc=function('NonExistingFunc')", 'E700:')
+    call assert_fails("LET &imactivatefunc = function('NonExistingFunc')", 'E700:')
+    call assert_fails("LET &imstatusfunc = function('NonExistingFunc')", 'E700:')
+    normal! i
+
+    call assert_equal(13, g:IMactivatefunc_called)
+    call assert_equal(26, g:IMstatusfunc_called)
+  END
+  call CheckLegacyAndVim9Success(lines)
 
-  call assert_fails("set imactivatefunc=function('abc')", "E700:")
-  call assert_fails("set imstatusfunc=function('abc')", "E700:")
-  call assert_fails("set imactivatefunc=funcref('abc')", "E700:")
-  call assert_fails("set imstatusfunc=funcref('abc')", "E700:")
+  " Using Vim9 lambda expression in legacy context should fail
+  set imactivatefunc=(a)\ =>\ IMactivatefunc1(a)
+  set imstatusfunc=IMstatusfunc1
+  call assert_fails('normal! i', 'E117:')
+  set imactivatefunc=IMactivatefunc1
+  set imstatusfunc=()\ =>\ IMstatusfunc1(a)
+  call assert_fails('normal! i', 'E117:')
 
-  call assert_equal(11, g:IMactivatefunc_called)
-  call assert_equal(22, g:IMstatusfunc_called)
+  " set 'imactivatefunc' and 'imstatusfunc' to a partial with dict. This used
+  " to cause a crash.
+  func SetIMFunc()
+    let params1 = {'activate': function('g:DictActivateFunc')}
+    let params2 = {'status': function('g:DictStatusFunc')}
+    let &imactivatefunc = params1.activate
+    let &imstatusfunc = params2.status
+  endfunc
+  func g:DictActivateFunc(_) dict
+  endfunc
+  func g:DictStatusFunc(_) dict
+  endfunc
+  call SetIMFunc()
+  new
+  call SetIMFunc()
+  bw
+  call test_garbagecollect_now()
+  new
+  set imactivatefunc=
+  set imstatusfunc=
+  wincmd w
+  set imactivatefunc=
+  set imstatusfunc=
+  :%bw!
+  delfunc g:DictActivateFunc
+  delfunc g:DictStatusFunc
+  delfunc SetIMFunc
 
   " Vim9 tests
   let lines =<< trim END
@@ -217,59 +276,12 @@ func Test_imactivatefunc_imstatusfunc_callback()
     set imstatusfunc=function('IMstatusfunc1')
     normal! i
 
-    # Test for using a lambda
-    &imactivatefunc = '(a) => IMactivatefunc1(a)'
-    &imstatusfunc = '() => IMstatusfunc1()'
-    normal! i
-
-    # Test for using a variable with a lambda expression
-    var Fn1: func = (active) => {
-           g:IMactivatefunc_called += 1
-           return 1
-        }
-    var Fn2: func = () => {
-           g:IMstatusfunc_called += 1
-           return 1
-        }
-    &imactivatefunc = Fn1
-    &imstatusfunc = Fn2
-    normal! i
-
-    # Test for using a string(variable with a lambda expression)
-    &imactivatefunc = string(Fn1)
-    &imstatusfunc = string(Fn2)
-    normal! i
-
-    assert_equal(4, g:IMactivatefunc_called)
-    assert_equal(8, g:IMstatusfunc_called)
-
     set iminsert=0
     set imactivatefunc=
     set imstatusfunc=
   END
   call CheckScriptSuccess(lines)
 
-  " Using Vim9 lambda expression in legacy context should fail
-  set imactivatefunc=(a)\ =>\ IMactivatefunc1(a)
-  set imstatusfunc=IMstatusfunc1
-  call assert_fails('normal! i', 'E117:')
-  set imactivatefunc=IMactivatefunc1
-  set imstatusfunc=()\ =>\ IMstatusfunc1(a)
-  call assert_fails('normal! i', 'E117:')
-
-  " set 'imactivatefunc' and 'imstatusfunc' to a non-existing function
-  set imactivatefunc=IMactivatefunc1
-  set imstatusfunc=IMstatusfunc1
-  call assert_fails("set imactivatefunc=function('NonExistingFunc')", 'E700:')
-  call assert_fails("set imstatusfunc=function('NonExistingFunc')", 'E700:')
-  call assert_fails("let &imactivatefunc = function('NonExistingFunc')", 'E700:')
-  call assert_fails("let &imstatusfunc = function('NonExistingFunc')", 'E700:')
-  let g:IMactivatefunc_called = 0
-  let g:IMstatusfunc_called = 0
-  normal! i
-  call assert_equal(2, g:IMactivatefunc_called)
-  call assert_equal(2, g:IMstatusfunc_called)
-
   " cleanup
   delfunc IMactivatefunc1
   delfunc IMstatusfunc1
diff --git a/src/testdir/test_ins_complete.vim b/src/testdir/test_ins_complete.vim
index 6a99ecd3eb..1303a13545 100644
--- a/src/testdir/test_ins_complete.vim
+++ b/src/testdir/test_ins_complete.vim
@@ -875,154 +875,179 @@ func Test_completefunc_callback()
     return a:findstart ? 0 : []
   endfunc
 
-  " Test for using a function()
-  set completefunc=function('MycompleteFunc1',[10])
-  new | only
-  call setline(1, 'one')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[10, 1, ''], [10, 0, 'one']], g:MycompleteFunc1_args)
-  bw!
+  let lines =<< trim END
+    #" Test for using a function()
+    set completefunc=function('g:MycompleteFunc1',\ [10])
+    new | only
+    call setline(1, 'one')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[10, 1, ''], [10, 0, 'one']], g:MycompleteFunc1_args)
+    bw!
 
-  " Using a funcref variable to set 'completefunc'
-  let Fn = function('MycompleteFunc1', [11])
-  let &completefunc = Fn
-  new | only
-  call setline(1, 'two')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[11, 1, ''], [11, 0, 'two']], g:MycompleteFunc1_args)
-  bw!
+    #" Using a funcref variable to set 'completefunc'
+    VAR Fn = function('g:MycompleteFunc1', [11])
+    LET &completefunc = Fn
+    new | only
+    call setline(1, 'two')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[11, 1, ''], [11, 0, 'two']], g:MycompleteFunc1_args)
+    bw!
 
-  " Using string(funcref_variable) to set 'completefunc'
-  let Fn = function('MycompleteFunc1', [12])
-  let &completefunc = string(Fn)
-  new | only
-  call setline(1, 'two')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[12, 1, ''], [12, 0, 'two']], g:MycompleteFunc1_args)
-  bw!
+    #" Using string(funcref_variable) to set 'completefunc'
+    LET Fn = function('g:MycompleteFunc1', [12])
+    LET &completefunc = string(Fn)
+    new | only
+    call setline(1, 'two')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[12, 1, ''], [12, 0, 'two']], g:MycompleteFunc1_args)
+    bw!
 
-  " Test for using a funcref()
-  set completefunc=funcref('MycompleteFunc1',\ [13])
-  new | only
-  call setline(1, 'three')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[13, 1, ''], [13, 0, 'three']], g:MycompleteFunc1_args)
-  bw!
+    #" Test for using a funcref()
+    set completefunc=funcref('g:MycompleteFunc1',\ [13])
+    new | only
+    call setline(1, 'three')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[13, 1, ''], [13, 0, 'three']], g:MycompleteFunc1_args)
+    bw!
 
-  " Using a funcref variable to set 'completefunc'
-  let Fn = funcref('MycompleteFunc1', [14])
-  let &completefunc = Fn
-  new | only
-  call setline(1, 'four')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[14, 1, ''], [14, 0, 'four']], g:MycompleteFunc1_args)
-  bw!
+    #" Using a funcref variable to set 'completefunc'
+    LET Fn = funcref('g:MycompleteFunc1', [14])
+    LET &completefunc = Fn
+    new | only
+    call setline(1, 'four')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[14, 1, ''], [14, 0, 'four']], g:MycompleteFunc1_args)
+    bw!
 
-  " Using a string(funcref_variable) to set 'completefunc'
-  let Fn = funcref('MycompleteFunc1', [15])
-  let &completefunc = string(Fn)
-  new | only
-  call setline(1, 'four')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[15, 1, ''], [15, 0, 'four']], g:MycompleteFunc1_args)
-  bw!
+    #" Using a string(funcref_variable) to set 'completefunc'
+    LET Fn = funcref('g:MycompleteFunc1', [15])
+    LET &completefunc = string(Fn)
+    new | only
+    call setline(1, 'four')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[15, 1, ''], [15, 0, 'four']], g:MycompleteFunc1_args)
+    bw!
 
-  " Test for using a lambda function
-  set completefunc={a,\ b\ ->\ MycompleteFunc1(16,\ a,\ b)}
-  new | only
-  call setline(1, 'five')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[16, 1, ''], [16, 0, 'five']], g:MycompleteFunc1_args)
-  bw!
+    #" Test for using a lambda function with set
+    VAR optval = "LSTART a, b LMIDDLE MycompleteFunc1(16, a, b) LEND"
+    LET optval = substitute(optval, ' ', '\\ ', 'g')
+    exe "set completefunc=" .. optval
+    new | only
+    call setline(1, 'five')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[16, 1, ''], [16, 0, 'five']], g:MycompleteFunc1_args)
+    bw!
 
-  " Set 'completefunc' to a lambda expression
-  let &completefunc = {a, b -> MycompleteFunc1(17, a, b)}
-  new | only
-  call setline(1, 'six')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[17, 1, ''], [17, 0, 'six']], g:MycompleteFunc1_args)
-  bw!
+    #" Set 'completefunc' to a lambda expression
+    LET &completefunc = LSTART a, b LMIDDLE MycompleteFunc1(17, a, b) LEND
+    new | only
+    call setline(1, 'six')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[17, 1, ''], [17, 0, 'six']], g:MycompleteFunc1_args)
+    bw!
 
-  " Set 'completefunc' to string(lambda_expression)
-  let &completefunc = '{a, b -> MycompleteFunc1(18, a, b)}'
-  new | only
-  call setline(1, 'six')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[18, 1, ''], [18, 0, 'six']], g:MycompleteFunc1_args)
-  bw!
+    #" Set 'completefunc' to string(lambda_expression)
+    LET &completefunc = 'LSTART a, b LMIDDLE MycompleteFunc1(18, a, b) LEND'
+    new | only
+    call setline(1, 'six')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[18, 1, ''], [18, 0, 'six']], g:MycompleteFunc1_args)
+    bw!
 
-  " Set 'completefunc' to a variable with a lambda expression
-  let Lambda = {a, b -> MycompleteFunc1(19, a, b)}
-  let &completefunc = Lambda
-  new | only
-  call setline(1, 'seven')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[19, 1, ''], [19, 0, 'seven']], g:MycompleteFunc1_args)
-  bw!
+    #" Set 'completefunc' to a variable with a lambda expression
+    VAR Lambda = LSTART a, b LMIDDLE MycompleteFunc1(19, a, b) LEND
+    LET &completefunc = Lambda
+    new | only
+    call setline(1, 'seven')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[19, 1, ''], [19, 0, 'seven']], g:MycompleteFunc1_args)
+    bw!
 
-  " Set 'completefunc' to a string(variable with a lambda expression)
-  let Lambda = {a, b -> MycompleteFunc1(20, a, b)}
-  let &completefunc = string(Lambda)
-  new | only
-  call setline(1, 'seven')
-  let g:MycompleteFunc1_args = []
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  call assert_equal([[20, 1, ''], [20, 0, 'seven']], g:MycompleteFunc1_args)
-  bw!
+    #" Set 'completefunc' to a string(variable with a lambda expression)
+    LET Lambda = LSTART a, b LMIDDLE MycompleteFunc1(20, a, b) LEND
+    LET &completefunc = string(Lambda)
+    new | only
+    call setline(1, 'seven')
+    LET g:MycompleteFunc1_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[20, 1, ''], [20, 0, 'seven']], g:MycompleteFunc1_args)
+    bw!
 
-  " Test for using a lambda function with incorrect return value
-  let Lambda = {s -> strlen(s)}
-  let &completefunc = Lambda
-  new | only
-  call setline(1, 'eight')
-  call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
-  bw!
+    #" Test for using a lambda function with incorrect return value
+    LET Lambda = LSTART a, b LMIDDLE strlen(a) LEND
+    LET &completefunc = Lambda
+    new | only
+    call setline(1, 'eight')
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    bw!
 
-  " Test for clearing the 'completefunc' option
-  set completefunc=''
-  set completefunc&
+    #" Test for clearing the 'completefunc' option
+    set completefunc=''
+    set completefunc&
+    call assert_fails("set completefunc=function('abc')", "E700:")
+    call assert_fails("set completefunc=funcref('abc')", "E700:")
+
+    #" set 'completefunc' to a non-existing function
+    func MycompleteFunc2(findstart, base)
+      call add(g:MycompleteFunc2_args, [a:findstart, a:base])
+      return a:findstart ? 0 : []
+    endfunc
+    set completefunc=MycompleteFunc2
+    call setline(1, 'five')
+    call assert_fails("set completefunc=function('NonExistingFunc')", 'E700:')
+    call assert_fails("LET &completefunc = function('NonExistingFunc')", 'E700:')
+    LET g:MycompleteFunc2_args = []
+    call feedkeys("A\<C-X>\<C-U>\<Esc>", 'x')
+    call assert_equal([[1, ''], [0, 'five']], g:MycompleteFunc2_args)
+    bw!
+  END
+  call CheckLegacyAndVim9Succ