patch 8.2.3179: Vim9: cannot assign to an imported variable at script level

Problem:    Vim9: cannot assign to an imported variable at script level.
Solution:   Lookup imported items when assigning.

src/errors.h

@@ -506,3 +506,5 @@ EXTERN char e_list_required_for_argument_nr[]
 	INIT(= N_("E1211: List required for argument %d"));
 EXTERN char e_bool_required_for_argument_nr[]
 	INIT(= N_("E1211: Bool required for argument %d"));
+EXTERN char e_redefining_imported_item_str[]
+	INIT(= N_("E1212: Redefining imported item %s"));

src/eval.c

@@ -1358,7 +1358,8 @@ set_var_lval(
 			 || (!var_check_ro(di->di_flags, lp->ll_name, FALSE)
 			   && !tv_check_lock(&di->di_tv, lp->ll_name, FALSE)))
 			&& tv_op(&tv, rettv, op) == OK)
-		    set_var(lp->ll_name, &tv, FALSE);
+		    set_var_const(lp->ll_name, NULL, &tv, FALSE,
+							    ASSIGN_NO_DECL, 0);
 		clear_tv(&tv);
 	    }
 	}

src/evalvars.c

@@ -3201,6 +3201,7 @@ set_var_const(
     typval_T	*tv = tv_arg;
     typval_T	bool_tv;
     dictitem_T	*di;
+    typval_T	*dest_tv = NULL;
     char_u	*varname;
     hashtab_T	*ht;
     int		is_script_local;
@@ -3241,6 +3242,31 @@ set_var_const(
 
     di = find_var_in_ht(ht, 0, varname, TRUE);
 
+    if (di == NULL && var_in_vim9script)
+    {
+	imported_T  *import = find_imported(varname, 0, NULL);
+
+	if (import != NULL)
+	{
+	    scriptitem_T    *si = SCRIPT_ITEM(import->imp_sid);
+	    svar_T	    *sv;
+
+	    // imported variable from another script
+	    if ((flags & ASSIGN_NO_DECL) == 0)
+	    {
+		semsg(_(e_redefining_imported_item_str), name);
+		goto failed;
+	    }
+	    sv = ((svar_T *)si->sn_var_vals.ga_data)
+						    + import->imp_var_vals_idx;
+	    // TODO: check the type
+	    // TODO: check for const and locked
+	    dest_tv = sv->sv_tv;
+	}
+    }
+
+    if (dest_tv == NULL)
+    {
 	// Search in parent scope which is possible to reference from lambda
 	if (di == NULL)
 	    di = find_var_in_scoped_ht(name, TRUE);
@@ -3402,21 +3428,24 @@ set_var_const(
 					     (flags & ASSIGN_NO_MEMBER_TYPE) == 0);
 	}
 
+	dest_tv = &di->di_tv;
+    }
+
     if (copy || tv->v_type == VAR_NUMBER || tv->v_type == VAR_FLOAT)
-	copy_tv(tv, &di->di_tv);
+	copy_tv(tv, dest_tv);
     else
     {
-	di->di_tv = *tv;
+	*dest_tv = *tv;
-	di->di_tv.v_lock = 0;
+	dest_tv->v_lock = 0;
 	init_tv(tv);
     }
 
     if (vim9script && type != NULL)
     {
-	if (type->tt_type == VAR_DICT && di->di_tv.vval.v_dict != NULL)
+	if (type->tt_type == VAR_DICT && dest_tv->vval.v_dict != NULL)
-	    di->di_tv.vval.v_dict->dv_type = alloc_type(type);
+	    dest_tv->vval.v_dict->dv_type = alloc_type(type);
-	else if (type->tt_type == VAR_LIST && di->di_tv.vval.v_list != NULL)
+	else if (type->tt_type == VAR_LIST && dest_tv->vval.v_list != NULL)
-	    di->di_tv.vval.v_list->lv_type = alloc_type(type);
+	    dest_tv->vval.v_list->lv_type = alloc_type(type);
     }
 
     // ":const var = value" locks the value
@@ -3425,8 +3454,9 @@ set_var_const(
 	// Like :lockvar! name: lock the value and what it contains, but only
 	// if the reference count is up to one.  That locks only literal
 	// values.
-	item_lock(&di->di_tv, DICT_MAXNEST, TRUE, TRUE);
+	item_lock(dest_tv, DICT_MAXNEST, TRUE, TRUE);
     return;
+
 failed:
     if (!copy)
 	clear_tv(tv_arg);

src/testdir/test_vim9_script.vim

@@ -1062,6 +1062,12 @@ let s:export_script_lines =<< trim END
   export def Exported(): string
     return 'Exported'
   enddef
+  export def ExportedValue(): number
+    return exported
+  enddef
+  export def ExportedInc()
+    exported += 5
+  enddef
   export final theList = [1]
 END
 
@@ -1073,10 +1079,21 @@ enddef
 def Test_vim9_import_export()
   var import_script_lines =<< trim END
     vim9script
-    import {exported, Exported} from './Xexport.vim'
+    import {exported, Exported, ExportedValue} from './Xexport.vim'
-    g:imported = exported
+    g:exported1 = exported
     exported += 3
-    g:imported_added = exported
+    g:exported2 = exported
+    g:exported3 = ExportedValue()
+
+    import ExportedInc from './Xexport.vim'
+    ExportedInc()
+    g:exported_i1 = exported
+    g:exported_i2 = ExportedValue()
+
+    exported = 11
+    g:exported_s1 = exported
+    g:exported_s2 = ExportedValue()
+
     g:imported_func = Exported()
 
     def GetExported(): string
@@ -1091,7 +1108,7 @@ def Test_vim9_import_export()
     g:imported_name = exp_name
     exp_name ..= ' Doe'
     g:imported_name_appended = exp_name
-    g:imported_later = exported
+    g:exported_later = exported
 
     import theList from './Xexport.vim'
     theList->add(2)
@@ -1105,9 +1122,17 @@ def Test_vim9_import_export()
 
   assert_equal('bobbie', g:result)
   assert_equal('bob', g:localname)
-  assert_equal(9876, g:imported)
+  assert_equal(9876, g:exported1)
-  assert_equal(9879, g:imported_added)
+  assert_equal(9879, g:exported2)
-  assert_equal(9879, g:imported_later)
+  assert_equal(9879, g:exported3)
+
+  assert_equal(9884, g:exported_i1)
+  assert_equal(9884, g:exported_i2)
+
+  assert_equal(11, g:exported_s1)
+  assert_equal(11, g:exported_s2)
+  assert_equal(11, g:exported_later)
+
   assert_equal('Exported', g:imported_func)
   assert_equal('Exported', g:funcref_result)
   assert_equal('John', g:imported_name)
@@ -1115,9 +1140,12 @@ def Test_vim9_import_export()
   assert_false(exists('g:name'))
 
   Undo_export_script_lines()
-  unlet g:imported
+  unlet g:exported1
-  unlet g:imported_added
+  unlet g:exported2
-  unlet g:imported_later
+  unlet g:exported3
+  unlet g:exported_i1
+  unlet g:exported_i2
+  unlet g:exported_later
   unlet g:imported_func
   unlet g:imported_name g:imported_name_appended
   delete('Ximport.vim')
@@ -1131,22 +1159,22 @@ def Test_vim9_import_export()
         }
         from
         './Xexport.vim'
-    g:imported = exported
+    g:exported = exported
-    exported += 5
+    exported += 7
-    g:imported_added = exported
+    g:exported_added = exported
     g:imported_func = Exported()
   END
   writefile(import_line_break_script_lines, 'Ximport_lbr.vim')
   source Ximport_lbr.vim
 
-  assert_equal(9876, g:imported)
+  assert_equal(11, g:exported)
-  assert_equal(9881, g:imported_added)
+  assert_equal(18, g:exported_added)
   assert_equal('Exported', g:imported_func)
 
   # exported script not sourced again
   assert_false(exists('g:result'))
-  unlet g:imported
+  unlet g:exported
-  unlet g:imported_added
+  unlet g:exported_added
   unlet g:imported_func
   delete('Ximport_lbr.vim')
 
@@ -1154,18 +1182,20 @@ def Test_vim9_import_export()
     vim9script
     import * as Export from './Xexport.vim'
     def UseExport()
-      g:imported_def = Export.exported
+      g:exported_def = Export.exported
     enddef
-    g:imported_script = Export.exported
+    g:exported_script = Export.exported
     assert_equal(1, exists('Export.exported'))
     assert_equal(0, exists('Export.notexported'))
     UseExport()
   END
   writefile(import_star_as_lines, 'Ximport.vim')
   source Ximport.vim
-  # FIXME: this should be 9881
+
-  assert_equal(9876, g:imported_def)
+  assert_equal(18, g:exported_def)
-  assert_equal(9876, g:imported_script)
+  assert_equal(18, g:exported_script)
+  unlet g:exported_def
+  unlet g:exported_script
 
   var import_star_as_lines_no_dot =<< trim END
     vim9script
@@ -1234,13 +1264,14 @@ def Test_vim9_import_export()
         from
         './Xexport.vim'
     def UseExport()
-      g:imported = Export.exported
+      g:exported = Export.exported
     enddef
     UseExport()
   END
   writefile(import_star_as_lbr_lines, 'Ximport.vim')
   source Ximport.vim
-  assert_equal(9876, g:imported)
+  assert_equal(18, g:exported)
+  unlet g:exported
 
   var import_star_lines =<< trim END
     vim9script

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3179,
 /**/
     3178,
 /**/