PHP_OUTPUT_HANDLER_HOOK_IMMUTABLE 431 ext/iconv/iconv.c php_output_handler_hook(PHP_OUTPUT_HANDLER_HOOK_IMMUTABLE, NULL TSRMLS_CC); PHP_OUTPUT_HANDLER_HOOK_IMMUTABLE 236 ext/zlib/zlib.c php_output_handler_hook(PHP_OUTPUT_HANDLER_HOOK_IMMUTABLE, NULL TSRMLS_CC); PHP_OUTPUT_HANDLER_HOOK_IMMUTABLE 700 main/output.c case PHP_OUTPUT_HANDLER_HOOK_IMMUTABLE: