# New Ticket Created by Audrey Tang # Please include the string: [perl #39711] # in the subject line of all future correspondence about this issue. # <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=39711 >
Currently, if you use IMCC inside embedded parrot (eg. when compiling via PGE), when a syntax error occurs, imcc calls Parrot_exit (or downright exit() -- see imclexer.c)), and it terminates the interpreter right there without any chance of recover. However, we can't easily make that throwing an exception, because IMCC currently relies on a lot of static globals to carry state, and cannot reliably restore them when an error occurs. (grep for "static" and "FIXME global" in the IMCC tree.) Moreover, the :immediate feature, currently unused (except to load dynamic lex pad, as a backdoor workaround for the design) and undocumented, allows running arbitrary code inside the .pir->.pbc emitter; that means each .pir compilation can potentially affect the state of the environment. In short, a .pir file can compile to drastically different .pbc file, depending on the phase of the moon, etc. Currently in all Parrot-targetting languages, only Perl 6 has that kind of evaluation-during-compilation feature, via its BEGIN block; however, due to Perl 6's doctrine of separate compilation, the BEGIN block has be compiled separately as another .pbc anyway; that means nobody has a legitimate use of :immediate at this point. I argue that :immediate should be retired, and static globals should be removed from IMCC. There is no drawback (as currently there are no real uses and it's undocumented), and the benefits are: - External non-parrot tools can manipulate .pir without exposing themselves to the security risks of carrying a full Parrot interpreter. - IMCC can regain the ability to compile .pir to .pasm. - It will be safe to recover from a .pir parsefail for Parrot embedders. - .pir->.pbc is made into a deterministic process, which makes .pir fingerprinting possible. Thanks, Audrey
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