RFC: https://wiki.php.net/rfc/partial_function_application_v2
For FCCs, the parser generates a normal function call AST node, the but argument
list is a ZEND_AST_CALLABLE_CONVERT / zend_ast_fcc node.
We extend this for PFAs so that zend_ast_fcc can represent arguments.
* Support PFA syntax in grammar
* Update zend_ast_fcc so that arguments can be represented
* Support serialization of zend_ast_fcc arguments in SHM / file cache
* Introduce zend_ast_arg_list_add(): Same as zend_ast_list_add(), but wraps the
list in a ZEND_AST_CALLABLE_CONVERT when adding any placeholder argument.
Technically the arg list wrapping is not required, but it results in simpler
code later as it will be very convenient in the compiler (determines whether a
function calls is a PFA/FCC), and for PFA-in-const-expr support. It also allows
to unify FCCs and PFAs in the grammar.
Closes GH-20717.
This cache is implemented in two levels: A EG(callable_convert_cache) global
that maps zend_function pointers to a shared callable instance, and a
CALLABLE_CONVERT cache slot to remember the result of the hash table lookup.
Fixes GH-19754
Closes GH-19863
Move some low-hanging fruit, creating new directories for the tests for
* access modifiers
* `class_alias()`
* constant expressions
* constructor property promotion
* `__debugInfo()`
* dereferencing
* first class callable syntax
Additionally, move some tests into the existing subdirectory for
closure-related tests
Work towards GH-15631
