PHP errors, unlike exceptions, are much more limited in programmers' ability to control their handling and get detailed information about them. I propose to fix some of these issues by recording a backtrace for every error.
This problem is so serious that, for example, Wikimedia has created an extension for this.
Add backtraces to error output.
Error output: traces will be formatted exactly like for exceptions, and appended to error messages, e.g.:
Fatal error: Allowed memory size of 134217728 bytes exhausted in /var/www/test.php on line 123
#0 /var/www/test.php(123): spl_eat_all_memory()
#1 /var/www/foo.php(456): foo(123, 'foo')
#2 /var/www/bar.php(789): bar()
#3 {main}
Logging: backtraces will be logged just like for exceptions.
error_get_last() output will have another element added to it if a trace is available:
#1 {main}
array(5) {
["type"]=>
int(1)
["message"]=>
string(22) "Error, terrible error!"
["file"]=>
string(17) "/var/www/test.php"
["line"]=>
int(3)
["backtrace"]=>
string(123) "#0 /var/www/test.php(345): $this->causeTerribleError()
#1 {main}"
}
Configuration: while always having backtraces is nice for debugging, some people might not like the performance overhead of generating backtraces or the risk of having to generate a trace after a fatal error. I therefore propose to address this with an INI setting, debug_backtraces that allows to turn this feature on and off, as well as to limit the number of stack frames outputted:
By default it would be on in development settings but off in production.
E_UNHANDLED_EXCEPTION is introduced to avoid outputting backtraces for unhandled exceptions twice, though it's not included in E_ALL and is invisible for userspace.8.0
For error_backtraces:
Make sure there are no open issues when the vote starts!
Everything other than the minor stuff mentioned in Backward Incompatible Changes.
Backtrace handling code could use some unification and refactoring, but that doesn't require a RFC and thus can be addressed later.
Links to external references, discussions or RFCs
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