__halt_compiler

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This function can be used in eval() -- it will halt the eval, but not the script eval"() was called in.

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If "__halt_compiler();" appears in a file which is "include"d or "require"d, then the called-in file will be treated as if it physically cuts off at the "__halt_compiler();". In other words, "__halt_compiler();" only affects the physical file it's in, an outer file that pulls it in will continue to execute.

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__halt_compiler is also useful for debugging. If you need to temporarily make a change that will introduce an error later on, use __halt_compiler to prevent syntax errors. For example:<?phpif ( $something ):  print 'something';endif;   // endif placed here for debugging purposes__halt_compiler();endif;   // original location of endif -- would produce syntax error if __halt_compiler was not there?>

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Please note that __HALT_COMPILER() must be uppercase if used from a pharstub: https://www.php.net/manual/en/phar.fileformat.stub.php

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I don't exactly know what PHP is doing internally but I don't understand the sanity behind how in token_get_all __halt_compiler is handled.This is actually valid there:__halt_compiler/**/ /**/ /**/ /**/ /** */();rawNormally it pops off just any three tokens so you can have even __halt_compiler***, __halt_compiler))), etc in token _get all.The weird thing is that is also skips T_OPEN_TAG but in the context __halt_compiler runs in this tag should not be posible. Instead it will pick up < and ? as operators and php as a T_STRING.It ignores the token at any point so this is also valid:__halt_compiler()/**/ /**/ /**/ /**/ /** */;rawWhen I test this with a php file rather than the tokeniser it works the same.I can only conclude that PHP/__halt_compiler is pretty weird.I think this is from attempting to weakly imitate the same syntax handling as in functions (I guess you can put comments/whitespace anywhere). I find it annoying and counter productive though.Even this is valid:__halt_compiler// comment\n();rawA general problem that compound matters is that tokenise wont check whether or not syntax is valid (tokens against each other). When running as PHP you must have ();.

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Joey, you're wrong saying that __halt_compiler have strange behavior. This structure works exactly the same as any other build in structure like empty or isset (even similarly to functions; at least in tokenizer level).About T_OPEN_TAG - after one open tag is present you didn't expect other one in current php code section, so tokenizer try to handle this "thing" in other way and it's perfectly normal...

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if you find the value of __COMPILER_HALT_OFFSET__ is highly strange. Maybe...there are some complier optimization tools, like eAccelator(very old). When the program is pre-complied and cached, the __COMPILER_HALT_OFFSET__ will be 0 = =