Merge branch 'nullable_types' of github.com:morrisonlevi/php-src

* 'nullable_types' of github.com:morrisonlevi/php-src:
  Fix bug #71428
  Add nullable parameter types
  Implement nullable return types.

diff --cc NEWS
index 5bb69bd52a423f3cff3ba99a726a3bb34c94c161,9b26cdbda968cf6fc3367304d10a6548bac248c7..150586fe4708c86bd861a721da21c3ae6ad30140
--- 1/NEWS
--- 2/NEWS
+++ b/NEWS
@@@ -3,9 -3,6 +3,10 @@@ PH
  ?? ??? 2016, PHP 7.1.0
  
  - Core:
++  . Added nullable types. (Levi, Dmitry)
 +  . Added DFA optimization framework based on e-SSA form. (Dmitry, Nikita)
 +  . Added specialized opcode handlers (e.g. ZEND_ADD_LONG_NO_OVERFLOW).
 +    (Dmitry)
    . Change statement and fcall extension handlers to accept frame. (Joe)
    . Implemented safe execution timeout handling, that prevents rundom crashes
      after "Maximum execution time exceeded" error. (Dmitry)

diff --cc Zend/zend_compile.c
Simple merge

diff --cc Zend/zend_compile.h
Simple merge

diff --cc Zend/zend_inheritance.c
Simple merge

diff --cc Zend/zend_language_parser.y
index 5f233d6a3b8689c78c88ef4cda91fad1554c9103,7682d69b6879612c06e6a8e1081a4bf82d95fab5..44c5cfb12b506785ea7f27903dcb19b86086aaa8
--- 1/Zend/zend_language_parser.y
--- 2/Zend/zend_language_parser.y
+++ b/Zend/zend_language_parser.y
@@@ -249,9 -250,9 +249,9 @@@ static YYSIZE_T zend_yytnamerr(char*, c
  %type <ast> non_empty_parameter_list argument_list non_empty_argument_list property_list
  %type <ast> class_const_list class_const_decl name_list trait_adaptations method_body non_empty_for_exprs
  %type <ast> ctor_arguments alt_if_stmt_without_else trait_adaptation_list lexical_vars
 -%type <ast> lexical_var_list encaps_list array_pair_list non_empty_array_pair_list
 -%type <ast> assignment_list unkeyed_assignment_list keyed_assignment_list
 +%type <ast> lexical_var_list encaps_list
 +%type <ast> array_pair non_empty_array_pair_list array_pair_list
- %type <ast> isset_variable type return_type
+ %type <ast> isset_variable type return_type type_expr
  %type <ast> identifier
  
  %type <num> returns_ref function is_reference is_variadic variable_modifiers