patch 9.1.0523: Vim9: cannot downcast an object

Problem:  Vim9: cannot downcast an object (Ernie Rael)
Solution: Fix class downcasting issue (LemonBoy).

When casting an object from one class to another the target type may be
a subclass (downcast) or superclass (upcast) of the source one.
Upcasts require a runtime type check to be emitted.

Add a disassembly test.

fixes: #13244
closes: #15079

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

diff --git a/src/structs.h b/src/structs.h
index 7e21f0fc8b006889a69f1ed84c733881c6fcb151..63092115be991c6542f61089b1fe3b4383a1e8ee 100644 (file)
--- a/src/structs.h
+++ b/src/structs.h
@@ -4902,7 +4902,8 @@ typedef enum {
     WT_MEMBER,
     WT_METHOD,         // object method
     WT_METHOD_ARG,     // object method argument type
-    WT_METHOD_RETURN   // object method return type
+    WT_METHOD_RETURN,  // object method return type
+    WT_CAST,           // type cast
 } wherekind_T;
 
 // Struct used to pass the location of a type check.  Used in error messages to

diff --git a/src/testdir/test_vim9_class.vim b/src/testdir/test_vim9_class.vim
index 8e328c2ee89dbe2ad6cf1b75cc809fbd0fd50a2e..13e8ea6e0bcd36f210490f3be9d2dfc549e78854 100644 (file)
--- a/src/testdir/test_vim9_class.vim
+++ b/src/testdir/test_vim9_class.vim
@@ -10871,4 +10871,21 @@ def Test_class_member_init_typecheck()
   v9.CheckScriptFailure(lines, 'E1012: Type mismatch; expected string but got number', 6)
 enddef
 
+def Test_class_cast()
+  var lines =<< trim END
+    vim9script
+    class A
+    endclass
+    class B extends A
+      var mylen: number
+    endclass
+    def F(o: A): number
+      return (<B>o).mylen
+    enddef
+
+    defcompile F
+  END
+  v9.CheckScriptSuccess(lines)
+enddef
+
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker

diff --git a/src/testdir/test_vim9_disassemble.vim b/src/testdir/test_vim9_disassemble.vim
index 89dcceed5757e8c1298bf5fd1a3cf05c42cf5703..7746b23b4146859020edb7d1272c85623b561b44 100644 (file)
--- a/src/testdir/test_vim9_disassemble.vim
+++ b/src/testdir/test_vim9_disassemble.vim
@@ -1761,6 +1761,74 @@ def Test_disassemble_typecast()
         instr)
 enddef
 
+def Test_disassemble_object_cast()
+  # Downcasting.
+  var lines =<< trim END
+      vim9script
+      class A
+      endclass
+      class B extends A
+        var mylen: number
+      endclass
+      def F(o: A): number
+        return (<B>o).mylen
+      enddef
+
+      g:instr = execute('disassemble F')
+  END
+  v9.CheckScriptSuccess(lines)
+  assert_match('\<SNR>\d*_F\_s*' ..
+        'return (<B>o).mylen\_s*' ..
+        '0 LOAD arg\[-1\]\_s*' ..
+        '1 CHECKTYPE object<B> stack\[-1\]\_s*' ..
+        '2 OBJ_MEMBER 0\_s*' ..
+        '3 RETURN\_s*',
+        g:instr)
+
+  # Upcasting.
+  lines =<< trim END
+      vim9script
+      class A
+        var mylen: number
+      endclass
+      class B extends A
+      endclass
+      def F(o: B): number
+        return (<A>o).mylen
+      enddef
+
+      g:instr = execute('disassemble F')
+  END
+  v9.CheckScriptSuccess(lines)
+  assert_match('\<SNR>\d*_F\_s*' ..
+        'return (<A>o).mylen\_s*' ..
+        '0 LOAD arg\[-1\]\_s*' ..
+        '1 OBJ_MEMBER 0\_s*' ..
+        '2 RETURN\_s*',
+        g:instr)
+
+  # Casting, type is not statically known.
+  lines =<< trim END
+      vim9script
+      class A
+      endclass
+      class B extends A
+      endclass
+      def F(o: any): any
+        return <A>o
+      enddef
+
+      g:instr = execute('disassemble F')
+  END
+  v9.CheckScriptSuccess(lines)
+  assert_match('\<SNR>\d*_F\_s*' ..
+        'return <A>o\_s*' ..
+        '0 LOAD arg\[-1\]\_s*' ..
+        '1 CHECKTYPE object<A> stack\[-1\]\_s*' ..
+        '2 RETURN\_s*',
+        g:instr)
+enddef
+
 def s:Computing()
   var nr = 3
   var nrres = nr + 7

diff --git a/src/version.c b/src/version.c
index 249d1c5493d976657abbab3154264c0a4336c75f..6588f2f9add0f0b2f52bf6f0d0e16c72c4fcccad 100644 (file)
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    523,
 /**/
     522,
 /**/

diff --git a/src/vim9compile.c b/src/vim9compile.c
index 61fefa767ed33d94f58b38324448cc4096e9bad2..ea305b7b34bb5213e7f2d1d507a2f6493c641af5 100644 (file)
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -522,6 +522,8 @@ use_typecheck(type_T *actual, type_T *expected)
                    (actual->tt_member == &t_void)
                                         == (expected->tt_member == &t_void))))
        return TRUE;
+    if (actual->tt_type == VAR_OBJECT && expected->tt_type == VAR_OBJECT)
+       return TRUE;
     if ((actual->tt_type == VAR_LIST || actual->tt_type == VAR_DICT)
                                       && actual->tt_type == expected->tt_type)
        // This takes care of a nested list or dict.

diff --git a/src/vim9expr.c b/src/vim9expr.c
index 8c412b876d8db4ca2aed6ee93c7dc0a35ace511b..7af8bd63b3a4feacfd5d2268ad203893bed26e15 100644 (file)
--- a/src/vim9expr.c
+++ b/src/vim9expr.c
@@ -2836,12 +2836,13 @@ compile_expr8(char_u **arg, cctx_T *cctx, ppconst_T *ppconst)
        type_T      *actual;
        where_T     where = WHERE_INIT;
 
+       where.wt_kind = WT_CAST;
        generate_ppconst(cctx, ppconst);
        actual = get_type_on_stack(cctx, 0);
        if (check_type_maybe(want_type, actual, FALSE, where) != OK)
        {
-           if (need_type(actual, want_type, FALSE,
-                                           -1, 0, cctx, FALSE, FALSE) == FAIL)
+           if (need_type_where(actual, want_type, FALSE, -1, where, cctx, FALSE, FALSE)
+                   == FAIL)
                return FAIL;
        }
     }

diff --git a/src/vim9type.c b/src/vim9type.c
index ffdf7facb946900d24a0c92a5ea1450f38c78464..a1571218f68672b6dc44ac7557c8edd423498be8 100644 (file)
--- a/src/vim9type.c
+++ b/src/vim9type.c
@@ -934,6 +934,7 @@ type_mismatch_where(type_T *expected, type_T *actual, where_T where)
                semsg(_(e_argument_nr_type_mismatch_expected_str_but_got_str_in_str),
                        where.wt_index, typename1, typename2, where.wt_func_name);
            break;
+       case WT_CAST:
        case WT_UNKNOWN:
            if (where.wt_func_name == NULL)
                semsg(_(e_type_mismatch_expected_str_but_got_str),
@@ -1090,7 +1091,15 @@ check_type_maybe(
                    ret = FAIL;
            }
            else if (!class_instance_of(actual->tt_class, expected->tt_class))
-               ret = FAIL;
+           {
+               // Check if this is an up-cast, if so we'll have to check the type at
+               // runtime.
+               if (where.wt_kind == WT_CAST &&
+                       class_instance_of(expected->tt_class, actual->tt_class))
+                   ret = MAYBE;
+               else
+                   ret = FAIL;
+           }
        }
 
        if (ret == FAIL && give_msg)