patch 9.0.1944: Vim9: function instruction pointer invalidated

Problem:  Vim9: function instruction pointer invalidated
Solution: Use the funcref index instead of the instruction pointer

closes: #13178
closes: #13196

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

src/proto/vim9instr.pro

@@ -45,7 +45,7 @@ int generate_OLDSCRIPT(cctx_T *cctx, isntype_T isn_type, char_u *name, int sid,
 int generate_VIM9SCRIPT(cctx_T *cctx, isntype_T isn_type, int sid, int idx, type_T *type);
 int generate_NEWLIST(cctx_T *cctx, int count, int use_null);
 int generate_NEWDICT(cctx_T *cctx, int count, int use_null);
-int generate_FUNCREF(cctx_T *cctx, ufunc_T *ufunc, class_T *cl, int fi, isn_T **isnp);
+int generate_FUNCREF(cctx_T *cctx, ufunc_T *ufunc, class_T *cl, int fi, int *isn_idx);
 int generate_NEWFUNC(cctx_T *cctx, char_u *lambda_name, char_u *func_name);
 int generate_DEF(cctx_T *cctx, char_u *name, size_t len);
 int generate_JUMP(cctx_T *cctx, jumpwhen_T when, int where);

src/testdir/test_vim9_script.vim

@@ -4636,6 +4636,56 @@ def Test_free_type_before_use()
   v9.CheckScriptSuccess(lines)
 enddef
 
+" The following complicated script used to cause an internal error (E340)
+" because the funcref instruction memory was referenced after the instruction
+" memory was reallocated (Github issue #13178)
+def Test_refer_funcref_instr_after_realloc()
+  var lines =<< trim END
+    vim9script
+    def A(d: bool)
+      var e = abs(0)
+      var f = &emoji
+      &emoji = true
+      if ['', '', '']->index('xxx') == 0
+        eval 0 + 0
+      endif
+      if &filetype == 'xxx'
+        var g = abs(0)
+        while g > 0
+          if getline(g) == ''
+            break
+          endif
+          --g
+        endwhile
+        if g == 0
+          return
+        endif
+        if d
+          feedkeys($'{g}G')
+          g = abs(0)
+        endif
+        var h = abs(0)
+        var i = abs(0)
+        var j = abs(0)
+        while j < 0
+          if abs(0) < h && getline(j) != ''
+          break
+          endif
+          ++j
+        endwhile
+        feedkeys($'{g}G{j}G')
+        return
+      endif
+      def B()
+      enddef
+      def C()
+      enddef
+    enddef
+    A(false)
+  END
+  v9.CheckScriptSuccess(lines)
+enddef
+
 " Keep this last, it messes up highlighting.
 def Test_substitute_cmd()
   new

src/version.c

@@ -699,6 +699,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1944,
 /**/
     1943,
 /**/

src/vim9compile.c

@@ -1029,7 +1029,7 @@ compile_nested_function(exarg_T *eap, cctx_T *cctx, garray_T *lines_to_free)
     ufunc_T	*ufunc;
     int		r = FAIL;
     compiletype_T   compile_type;
-    isn_T	*funcref_isn = NULL;
+    int		funcref_isn_idx = -1;
     lvar_T	*lvar = NULL;
 
     if (eap->forceit)
@@ -1148,7 +1148,7 @@ compile_nested_function(exarg_T *eap, cctx_T *cctx, garray_T *lines_to_free)
 					    ASSIGN_CONST, ufunc->uf_func_type);
 	if (lvar == NULL)
 	    goto theend;
-	if (generate_FUNCREF(cctx, ufunc, NULL, 0, &funcref_isn) == FAIL)
+	if (generate_FUNCREF(cctx, ufunc, NULL, 0, &funcref_isn_idx) == FAIL)
 	    goto theend;
 	r = generate_STORE(cctx, ISN_STORE, lvar->lv_idx, NULL);
     }
@@ -1178,8 +1178,12 @@ compile_nested_function(exarg_T *eap, cctx_T *cctx, garray_T *lines_to_free)
 #endif
 
     // If a FUNCREF instruction was generated, set the index after compiling.
-    if (funcref_isn != NULL && ufunc->uf_def_status == UF_COMPILED)
+    if (funcref_isn_idx != -1 && ufunc->uf_def_status == UF_COMPILED)
+    {
+	isn_T	*funcref_isn = ((isn_T *)cctx->ctx_instr.ga_data) +
+							funcref_isn_idx;
 	funcref_isn->isn_arg.funcref.fr_dfunc_idx = ufunc->uf_dfunc_idx;
+    }
 
 theend:
     vim_free(lambda_name);

src/vim9instr.c

@@ -1378,7 +1378,9 @@ generate_NEWDICT(cctx_T *cctx, int count, int use_null)
  * Generate an ISN_FUNCREF instruction.
  * For "obj.Method" "cl" is the class of the object (can be an interface or a
  * base class) and "fi" the index of the method on that class.
- * "isnp" is set to the instruction, so that fr_dfunc_idx can be set later.
+ * "isn_idx" is set to the index of the instruction, so that fr_dfunc_idx can
+ * be set later.  The index is used instead of a pointer to the instruction
+ * because the instruction memory can be reallocated.
  */
     int
 generate_FUNCREF(
@@ -1386,7 +1388,7 @@ generate_FUNCREF(
 	ufunc_T	    *ufunc,
 	class_T	    *cl,
 	int	    fi,
-	isn_T	    **isnp)
+	int	    *isn_idx)
 {
     isn_T	    *isn;
     type_T	    *type;
@@ -1397,8 +1399,9 @@ generate_FUNCREF(
     RETURN_OK_IF_SKIP(cctx);
     if ((isn = generate_instr(cctx, ISN_FUNCREF)) == NULL)
 	return FAIL;
-    if (isnp != NULL)
-	*isnp = isn;
+    if (isn_idx != NULL)
+	// save the index of the new instruction
+	*isn_idx = cctx->ctx_instr.ga_len - 1;
 
     has_vars = get_loop_var_info(cctx, &loopinfo);
     if (ufunc->uf_def_status == UF_NOT_COMPILED || has_vars || cl != NULL)
@@ -1419,7 +1422,7 @@ generate_FUNCREF(
 	extra->fre_func_name = vim_strsave(ufunc->uf_name);
     if (ufunc->uf_def_status != UF_NOT_COMPILED && cl == NULL)
     {
-	if (isnp == NULL && ufunc->uf_def_status == UF_TO_BE_COMPILED)
+	if (isn_idx == NULL && ufunc->uf_def_status == UF_TO_BE_COMPILED)
 	    // compile the function now, we need the uf_dfunc_idx value
 	    (void)compile_def_function(ufunc, FALSE, CT_NONE, NULL);
 	isn->isn_arg.funcref.fr_dfunc_idx = ufunc->uf_dfunc_idx;