Merge branch 'concatenation_precedence'

diff --cc UPGRADING
index 8dbcbc931106a5b061ef6c8e724a406a73d81a4c,1a563803e7473090275910ae966db3a3ca1c8dee..7f667cde5d94605699f186c0dd1e9ac69d35a814
--- 1/UPGRADING
--- 2/UPGRADING
+++ b/UPGRADING
@@@ -66,10 -66,6 +66,13 @@@ PHP 8.0 UPGRADE NOTE
      Additionally, care should be taken that error messages are not displayed in
      production environments, which can result in information leaks. Please
      ensure that display_errors=Off is used in conjunction with error logging.
 +  . Inheritance errors due to incompatible method signatures (LSP violations)
 +    will now always generate a fatal error. Previously a warning was generated
 +    in some cases.
 +    RFC: https://wiki.php.net/rfc/lsp_errors
++  . The precendence of the concatenation operator has changed relative to
++    bitshifts and addition as well as subtraction.
++    RFC: https://wiki.php.net/rfc/concatenation_precedence
  
  - COM:
    . Removed the ability to import case-insensitive constants from type

diff --cc Zend/zend_ast.c
Simple merge

diff --cc Zend/zend_language_parser.y
Simple merge