patch 8.2.2223: Vim9: Reloading marks a :def function as deleted

Problem:    Vim9: Reloading marks a :def function as deleted.
Solution:   Clear the function contents but keep the index.

runtime/doc/vim9.txt

@@ -219,23 +219,6 @@ some point when loaded again.  E.g. when a buffer local option is set: >
 	def g:SomeFunc()
 	....
 
-There is one gotcha: If a compiled function is replaced and it is called from
-another compiled function that is not replaced, it will try to call the
-function from before it was replaced, which no longer exists.  This doesn't
-work: >
-	vimscript noclear
-
-	def ReplaceMe()
-	  echo 'function redefined every time'
-	enddef
-
-	if exists('s:loaded') | finish | endif
-	var s:loaded = true
-
-	def NotReplaced()
-	  ReplaceMe()  # Error if ReplaceMe() was redefined
-	enddef
-
 
 Variable declarations with :var, :final and :const ~
 						*vim9-declaration* *:var*

src/testdir/test_vim9_script.vim

@@ -1174,10 +1174,7 @@ def Test_vim9script_reload_noclear()
     var s:notReloaded = 'yes'
     s:reloaded = 'first'
     def g:Values(): list<string>
-      return [s:reloaded, s:notReloaded, Once()]
-    enddef
-    def g:CallAgain(): string
-      return Again()
+      return [s:reloaded, s:notReloaded, Again(), Once()]
     enddef
 
     def Once(): string
@@ -1188,20 +1185,16 @@ def Test_vim9script_reload_noclear()
   g:loadCount = 0
   source XReloaded
   assert_equal(1, g:loadCount)
-  assert_equal(['first', 'yes', 'once'], g:Values())
-  assert_equal('again', g:CallAgain())
+  assert_equal(['first', 'yes', 'again', 'once'], g:Values())
   source XReloaded
   assert_equal(2, g:loadCount)
-  assert_equal(['init', 'yes', 'once'], g:Values())
-  assert_fails('call g:CallAgain()', 'E933:')
+  assert_equal(['init', 'yes', 'again', 'once'], g:Values())
   source XReloaded
   assert_equal(3, g:loadCount)
-  assert_equal(['init', 'yes', 'once'], g:Values())
-  assert_fails('call g:CallAgain()', 'E933:')
+  assert_equal(['init', 'yes', 'again', 'once'], g:Values())
 
   delete('Xreloaded')
   delfunc g:Values
-  delfunc g:CallAgain
   unlet g:loadCount
 enddef
 

src/userfunc.c

@@ -3628,7 +3628,7 @@ define_function(exarg_T *eap, char_u *name_arg)
 		fp->uf_profiling = FALSE;
 		fp->uf_prof_initialized = FALSE;
 #endif
-		unlink_def_function(fp);
+		fp->uf_def_status = UF_NOT_COMPILED;
 	    }
 	}
     }
@@ -3694,8 +3694,6 @@ define_function(exarg_T *eap, char_u *name_arg)
 	fp = alloc_clear(offsetof(ufunc_T, uf_name) + STRLEN(name) + 1);
 	if (fp == NULL)
 	    goto erret;
-	fp->uf_def_status = eap->cmdidx == CMD_def ? UF_TO_BE_COMPILED
-							     : UF_NOT_COMPILED;
 
 	if (fudi.fd_dict != NULL)
 	{

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2223,
 /**/
     2222,
 /**/

src/vim9compile.c

@@ -145,7 +145,7 @@ struct cctx_S {
     int		ctx_has_cmdmod;	    // ISN_CMDMOD was generated
 };
 
-static void delete_def_function_contents(dfunc_T *dfunc);
+static void delete_def_function_contents(dfunc_T *dfunc, int mark_deleted);
 
 /*
  * Lookup variable "name" in the local scope and return it in "lvar".
@@ -7498,12 +7498,12 @@ compile_def_function(ufunc_T *ufunc, int check_return_type, cctx_T *outer_cctx)
     int		new_def_function = FALSE;
 
     // When using a function that was compiled before: Free old instructions.
-    // Otherwise add a new entry in "def_functions".
+    // The index is reused.  Otherwise add a new entry in "def_functions".
     if (ufunc->uf_dfunc_idx > 0)
     {
 	dfunc_T *dfunc = ((dfunc_T *)def_functions.ga_data)
 							 + ufunc->uf_dfunc_idx;
-	delete_def_function_contents(dfunc);
+	delete_def_function_contents(dfunc, FALSE);
     }
     else
     {
@@ -8344,7 +8344,7 @@ delete_instr(isn_T *isn)
  * Free all instructions for "dfunc" except df_name.
  */
     static void
-delete_def_function_contents(dfunc_T *dfunc)
+delete_def_function_contents(dfunc_T *dfunc, int mark_deleted)
 {
     int idx;
 
@@ -8355,9 +8355,13 @@ delete_def_function_contents(dfunc_T *dfunc)
 	for (idx = 0; idx < dfunc->df_instr_count; ++idx)
 	    delete_instr(dfunc->df_instr + idx);
 	VIM_CLEAR(dfunc->df_instr);
+	dfunc->df_instr = NULL;
     }
 
+    if (mark_deleted)
 	dfunc->df_deleted = TRUE;
+    if (dfunc->df_ufunc != NULL)
+	dfunc->df_ufunc->uf_def_status = UF_NOT_COMPILED;
 }
 
 /*
@@ -8374,7 +8378,7 @@ unlink_def_function(ufunc_T *ufunc)
 							 + ufunc->uf_dfunc_idx;
 
 	if (--dfunc->df_refcount <= 0)
-	    delete_def_function_contents(dfunc);
+	    delete_def_function_contents(dfunc, TRUE);
 	ufunc->uf_def_status = UF_NOT_COMPILED;
 	ufunc->uf_dfunc_idx = 0;
 	if (dfunc->df_ufunc == ufunc)
@@ -8410,7 +8414,7 @@ free_def_functions(void)
     {
 	dfunc_T *dfunc = ((dfunc_T *)def_functions.ga_data) + idx;
 
-	delete_def_function_contents(dfunc);
+	delete_def_function_contents(dfunc, TRUE);
 	vim_free(dfunc->df_name);
     }