DIM on null in const expr should emit warning

Author: iluuu1994

Zend/tests/const_expr_dim_on_null_warning.phpt

@@ -0,0 +1,10 @@
+--TEST--
+DIM on null in constant expr should emit warning
+--FILE--
+<?php
+const C = (null)['foo'];
+var_dump(C);
+?>
+--EXPECTF--
+Warning: Trying to access array offset on value of type null in %s on line %d
+NULL

Zend/zend_compile.c

@@ -10544,7 +10544,7 @@ static void zend_eval_const_expr(zend_ast **ast_ptr) /* {{{ */
 				c = (zend_uchar) Z_STRVAL_P(container)[offset];
 				ZVAL_CHAR(&result, c);
 			} else if (Z_TYPE_P(container) <= IS_FALSE) {
-				ZVAL_NULL(&result);
+				return; /* warning... handle at runtime */
 			} else {
 				return;
 			}