Bug #79044 [Nab]: Curly Braces Throw T_LNUMBER Error

Edit report at https://bugs.php.net/bug.php?id=79044&edit=1 ID: 79044 Updated by: requinix@php.net Reported by: thebluewalrus at gmail dot com Summary: Curly Braces Throw T_LNUMBER Error Status: Not a bug Type: Bug Package: *General Issues Operating System: Mac OSX 10.12.4 PHP Version: 7.4.1 Block user comment: N Private report: N New Comment: > irrelevant By all means, please invent a time machine and go back a couple decades to tell the people developing PHP that they should have done this differently. That way people in the other timeline won't have to deal with such utterly ridiculous behavior. I know that for me, personally, if I were to fork PHP, prohibiting writing "$1" is at the top of my list of things to change. Meanwhile for those of us in this timeline, that's how it is. Unless, of course, you have a compelling reason why PHP should suddenly break functionality that has been allowed since basically forever? If you actually do despite my sarcasm, go ahead and start working on an RFC for it. I'm sure everyone will love it. Previous Comments: ------------------------------------------------------------------------ [2019-12-29 23:10:49] bugreports at gmail dot com irrelevant, the second one should throw the same error than the first and that can even throw at compile time php > echo $1test; Parse error: syntax error, unexpected '1' (T_LNUMBER), expecting variable (T_VARIABLE) or '{' or '$' in php shell code on line 1 php > echo "$1test"; $1test ------------------------------------------------------------------------ [2019-12-29 22:44:18] requinix@php.net Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php https://www.php.net/manual/en/language.types.string.php#language.types.string.parsing When PHP reads the simple syntax it sees the '$' and takes > as many tokens as possible to form a valid variable name No tokens means no variable and PHP ignores it. Complex syntax works differently as it > allows for the use of complex expressions With complex syntax PHP sees '{$' and everything up to the closing '}' is used. In other words, PHP looks for a valid expression - the kind you use in your regular code, but with the obvious limitation that it has to start with a dollar sign. "$1" is not a valid expression, and PHP raises the same syntax error that it would as if you wrote that outside of a string. ------------------------------------------------------------------------ [2019-12-29 21:21:15] thebluewalrus at gmail dot com Yes, I agree I would expect '"$1"' and '"{$1}"' to behave the same but they don't. I think one or the other is functioning incorrectly. Simplifying the "correct" example it still executes: preg_replace('/(a)/', "$1", 'a'); ------------------------------------------------------------------------ [2019-12-29 16:23:30] bugreports at gmail dot com you can't have variables starting with a number in PHP ----------------------- Correct behavior: preg_replace('/(a)/', "$1test", 'a'); i would say this is not correct behavior and should trhow the same error becasue you can't have a variable $1test nor can you have $1 ----------------------- php > $1test = 'test'; Parse error: syntax error, unexpected '1' (T_LNUMBER), expecting variable (T_VARIABLE) or '{' or '$' in php shell code on line 1 ------------------------------------------------------------------------ [2019-12-29 15:52:26] thebluewalrus at gmail dot com Description: ------------ Using curly braces and a backreference in double quotes in regex replacement produces a 'T_LNUMBER' error for an invalid variable name. This behavior is inconsistent with other behavior though, e.g. uncurled the "variable" doesn't throw parser error. Test script: --------------- Correct behavior: preg_replace('/(a)/', "$1test", 'a'); Incorrect behavior: preg_replace('/(a)/', "{$1}test", 'a'); Expected result: ---------------- In regex context this behaviors is incorrect because '{$3}' should produce '{capture group three value}', as it does outside the curly braces. Actual result: -------------- Parse error: syntax error, unexpected '1' (T_LNUMBER), expecting variable (T_VARIABLE) or '{' or '$' ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=79044&edit=1