patch 7.4.1755

Problem:    When using getreg() on a non-existing register a NULL list is
            returned. (Bjorn Linse)
Solution:   Allocate an empty list. Add a test.

Author: brammool

src/eval.c

@@ -6051,7 +6051,7 @@ list_alloc(void)
 }
 
 /*
- * Allocate an empty list for a return value.
+ * Allocate an empty list for a return value, with reference count set.
  * Returns OK or FAIL.
  */
     int
@@ -13173,7 +13173,9 @@ f_getreg(typval_T *argvars, typval_T *rettv)
 	rettv->v_type = VAR_LIST;
 	rettv->vval.v_list = (list_T *)get_reg_contents(regname,
 				      (arg2 ? GREG_EXPR_SRC : 0) | GREG_LIST);
-	if (rettv->vval.v_list != NULL)
+	if (rettv->vval.v_list == NULL)
+	    rettv_list_alloc(rettv);
+	else
 	    ++rettv->vval.v_list->lv_refcount;
     }
     else

src/testdir/test_expr.vim

@@ -74,3 +74,12 @@ func Test_strcharpart()
 
   call assert_equal('a', strcharpart('axb', -1, 2))
 endfunc
+
+func Test_getreg_empty_list()
+  call assert_equal('', getreg('x'))
+  call assert_equal([], getreg('x', 1, 1))
+  let x = getreg('x', 1, 1)
+  let y = x
+  call add(x, 'foo')
+  call assert_equal(['foo'], y)
+endfunc

src/version.c

@@ -748,6 +748,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1755,
 /**/
     1754,
 /**/