Stricter verification of func info against arg info

Make sure they're actually the same up to cases where func info
allows more accurate expressions. There are some awkward edge cases
around true/false/null limitations in union types.

Author: nikic

ext/opcache/Optimizer/zend_func_info.c

@@ -932,12 +932,23 @@ uint32_t zend_get_func_info(
 		}
 
 #if ZEND_DEBUG
-		/* Check whether the func_info information is a subset of the information we can compute
-		 * from the specified return type. */
 		if (internal_ret) {
+			/* Check whether the func_info information is a subset of the information we can
+			 * compute from the specified return type, otherwise it contains redundant types. */
 			if (internal_ret & ~ret) {
 				fprintf(stderr, "Inaccurate func info for %s()\n", ZSTR_VAL(lcname));
 			}
+			/* If the return type is not mixed, check that the types match exactly if we exclude
+			 * RC and array information. */
+			uint32_t ret_any = ret & MAY_BE_ANY, internal_ret_any = internal_ret & MAY_BE_ANY;
+			if (ret_any != MAY_BE_ANY) {
+				uint32_t diff = internal_ret_any ^ ret_any;
+				/* Func info may contain "true" types as well as isolated "null" and "false". */
+				if (diff && !(diff == MAY_BE_FALSE && (ret & MAY_BE_FALSE))
+						&& (internal_ret_any & ~(MAY_BE_NULL|MAY_BE_FALSE))) {
+					fprintf(stderr, "Incorrect func info for %s()\n", ZSTR_VAL(lcname));
+				}
+			}
 			return internal_ret;
 		}
 #endif