vbscript: Undefined variables resolve as EMPTY without Option Explicit.

dlls/vbscript/interp.c

@@ -206,7 +206,8 @@ static HRESULT lookup_identifier(exec_ctx_t *ctx, BSTR name, vbdisp_invoke_type_
     return S_OK;
 }
 
-static HRESULT add_dynamic_var(exec_ctx_t *ctx, const WCHAR *name, BOOL is_const, VARIANT *val, BOOL own_val)
+static HRESULT add_dynamic_var(exec_ctx_t *ctx, const WCHAR *name,
+        BOOL is_const, VARIANT *val, BOOL own_val, VARIANT **out_var)
 {
     dynamic_var_t *new_var;
     vbsheap_t *heap;
@@ -245,6 +246,9 @@ static HRESULT add_dynamic_var(exec_ctx_t *ctx, const WCHAR *name, BOOL is_const
         ctx->dynamic_vars = new_var;
     }
 
+    if(out_var)
+        *out_var = &new_var->v;
+
     return S_OK;
 }
 
@@ -526,6 +530,16 @@ static HRESULT do_icall(exec_ctx_t *ctx, VARIANT *res)
         }
         break;
     case REF_NONE:
+        if(res && !ctx->func->code_ctx->option_explicit && arg_cnt == 0) {
+            VARIANT v, *new;
+            VariantInit(&v);
+            hres = add_dynamic_var(ctx, identifier, FALSE, &v, FALSE, &new);
+            if(FAILED(hres))
+                return hres;
+            V_VT(res) = VT_BYREF|VT_VARIANT;
+            V_BYREF(res) = new;
+            break;
+        }
         FIXME("%s not found\n", debugstr_w(identifier));
         return DISP_E_UNKNOWNNAME;
     }
@@ -653,7 +667,7 @@ static HRESULT assign_ident(exec_ctx_t *ctx, BSTR name, DISPPARAMS *dp)
             }
 
             TRACE("creating variable %s\n", debugstr_w(name));
-            hres = add_dynamic_var(ctx, name, FALSE, dp->rgvarg, FALSE);
+            hres = add_dynamic_var(ctx, name, FALSE, dp->rgvarg, FALSE, NULL);
         }
     }
 
@@ -810,7 +824,7 @@ static HRESULT interp_const(exec_ctx_t *ctx)
     if(FAILED(hres))
         return hres;
 
-    return add_dynamic_var(ctx, arg, TRUE, val.v, val.owned);
+    return add_dynamic_var(ctx, arg, TRUE, val.v, val.owned, NULL);
 }
 
 static HRESULT interp_val(exec_ctx_t *ctx)

dlls/vbscript/tests/run.c

@@ -1780,6 +1780,8 @@ static void run_from_res(const char *name)
 
 static void run_tests(void)
 {
+    HRESULT hres;
+
     strict_dispid_check = TRUE;
 
     parse_script_a("");
@@ -1880,6 +1882,14 @@ static void run_tests(void)
                    "End Sub\n"
                    "Call testsub()");
 
+    parse_script_a("Call ok(getVT(x) = \"VT_EMPTY*\", \"getVT(x) = \" & getVT(x))\n");
+    parse_script_a("Call ok(x = \"\", \"x = \" & x)\n");
+    parse_script_a("x = y\n"
+                   "Call ok(getVT(x) = \"VT_EMPTY*\", \"getVT(x) = \" & getVT(x))\n"
+                   "Call ok(getVT(y) = \"VT_EMPTY*\", \"getVT(y) = \" & getVT(y))");
+    hres = parse_script_ar("x = y(\"a\")");
+    ok(FAILED(hres), "script didn't fail\n");
+
     run_from_res("lang.vbs");
     run_from_res("api.vbs");