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Date: Wed, 17 Oct 2018 13:59:28 +0200
To: PHP internals <internals@lists.php.net>
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Subject: Multiple use of ast node in parser
From: cschneid@cschneid.com (Christian Schneider)

I'm playing around with some syntactic sugar for PHP and when trying to =
implement
	:$foo
as equivalent for
	'foo' =3D> $foo
I ran into the problem of having only having one ast node but trying to =
use it twice.

My first attempt was
	| ':' T_VARIABLE
		{ $$ =3D zend_ast_create(ZEND_AST_ARRAY_ELEM, =
zend_ast_create(ZEND_AST_VAR, $2), $2); }
but that results in corrupted memory because of the double usage.

Trying something like
	| ':' T_VARIABLE
		{ $$ =3D zend_ast_create(ZEND_AST_ARRAY_ELEM, =
zend_ast_create(ZEND_AST_VAR, GC_AST(zend_ast_copy($2))), $2); }
works but leaks memory because the copied ast is not freed.

Is there a proper way to do something like this ast transformation =
inside the parser?

Regards,
- Chris