patch 9.0.1179: not all errors around inheritance are tested

Problem:    Not all errors around inheritance are tested.
Solution:   Add more tests.  Fix uncovered problems.

src/errors.h

@@ -3438,4 +3438,6 @@ EXTERN char e_super_must_be_followed_by_dot[]
 	INIT(= N_("E1356: \"super\" must be followed by a dot"));
 EXTERN char e_using_super_not_in_class_function[]
 	INIT(= N_("E1357: Using \"super\" not in a class function"));
+EXTERN char e_using_super_not_in_child_class[]
+	INIT(= N_("E1358: Using \"super\" not in a child class"));
 #endif

src/testdir/test_vim9_class.vim

@@ -838,6 +838,63 @@ def Test_class_extends()
       assert_equal('John: 42', o.ToString())
   END
   v9.CheckScriptSuccess(lines)
+
+  lines =<< trim END
+      vim9script
+      class Child
+        this.age: number
+        def ToString(): number
+          return this.age
+        enddef
+        def ToString(): string
+          return this.age
+        enddef
+      endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1355: Duplicate function: ToString')
+
+  lines =<< trim END
+      vim9script
+      class Child
+        this.age: number
+        def ToString(): string
+          return super .ToString() .. ': ' .. this.age
+        enddef
+      endclass
+      var o = Child.new(42)
+      echo o.ToString()
+  END
+  v9.CheckScriptFailure(lines, 'E1356:')
+
+  lines =<< trim END
+      vim9script
+      class Base
+        this.name: string
+        def ToString(): string
+          return this.name
+        enddef
+      endclass
+
+      var age = 42
+      def ToString(): string
+        return super.ToString() .. ': ' .. age
+      enddef
+      echo ToString()
+  END
+  v9.CheckScriptFailure(lines, 'E1357:')
+
+  lines =<< trim END
+      vim9script
+      class Child
+        this.age: number
+        def ToString(): string
+          return super.ToString() .. ': ' .. this.age
+        enddef
+      endclass
+      var o = Child.new(42)
+      echo o.ToString()
+  END
+  v9.CheckScriptFailure(lines, 'E1358:')
 enddef
 
 

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1179,
 /**/
     1178,
 /**/

src/vim9compile.c

@@ -49,6 +49,20 @@ lookup_local(char_u *name, size_t len, lvar_T *lvar, cctx_T *cctx)
 	    && (cctx->ctx_ufunc->uf_flags & (FC_OBJECT|FC_NEW)))
     {
 	int is_super = *name == 's';
+	if (is_super)
+	{
+	    if (name[5] != '.')
+	    {
+		emsg(_(e_super_must_be_followed_by_dot));
+		return FAIL;
+	    }
+	    if (cctx->ctx_ufunc->uf_class != NULL
+		    && cctx->ctx_ufunc->uf_class->class_extends == NULL)
+	    {
+		emsg(_(e_using_super_not_in_child_class));
+		return FAIL;
+	    }
+	}
 	if (lvar != NULL)
 	{
 	    CLEAR_POINTER(lvar);

src/vim9expr.c

@@ -268,14 +268,14 @@ compile_class_object_index(cctx_T *cctx, char_u **arg, type_T *type)
     if (type == &t_super)
     {
 	if (cctx->ctx_ufunc == NULL || cctx->ctx_ufunc->uf_class == NULL)
-	    emsg(_(e_using_super_not_in_class_function));
-	else
 	{
-	    is_super = TRUE;
-	    cl = cctx->ctx_ufunc->uf_class;
-	    // Remove &t_super from the stack.
-	    --cctx->ctx_type_stack.ga_len;
+	    emsg(_(e_using_super_not_in_class_function));
+	    return FAIL;
 	}
+	is_super = TRUE;
+	cl = cctx->ctx_ufunc->uf_class;
+	// Remove &t_super from the stack.
+	--cctx->ctx_type_stack.ga_len;
     }
     else if (type->tt_type == VAR_CLASS)
     {
@@ -2261,6 +2261,7 @@ compile_subscript(
 	    // class constructor: SomeClass.new()
 	    // object member: someObject.varname, this.varname
 	    // object method: someObject.SomeMethod(), this.SomeMethod()
+	    *arg = p;
 	    if (compile_class_object_index(cctx, arg, type) == FAIL)
 		return FAIL;
 	}