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Try to avoid recursive compilation of binary ops #8315
Description
Description
Hi there,
I’m really not sure that it’s a bug linked to PHP or Apache (related to Windows env) but I noticed a regression while trying to upgrade my env with all projects that runs Symfony en Windows 10. That’s also the case with Symfony demo app.
Steps to reproduce:
- Install XAMPP on Windows with PHP 8.0.5 or >
- Install Symfony demo as documented on https://github.com/symfony/demo
- See the problem when browsing the URL
As soon as I downgrade to PHP 7.4 or even 8.0.3 I don’t have the issue anymore.
Sorry not being able to find accurately what is the root cause. As you are experts maybe you could help to check what is the cause of this regression?
See related ticket for more details:
symfony/monolog-bundle#412
PHP Version
PHP 8.1.4
Operating System
Windows 10
Activity
cmb69 commentedon Apr 7, 2022
This is a stack overflow during compilation.
Stack backtrace:
The chaining of method calls in that file requires an awful lot of stack space to be compiled; I don't think that we can reasonably fix this.
cmb69 commentedon Apr 7, 2022
@Seldaek, any ideas what to do here? https://github.com/symfony/monolog-bundle/blob/master/DependencyInjection/Configuration.php has so many chained method calls, that compilation may fail due to stack overflow. Is it feasible to rewrite that file? Or would you suggest that we somehow flatten the recursion during compilation?
bwoebi commentedon Apr 7, 2022
I've been hitting this with generated code as well, the "solution" was then introducing temporary variables in the code generator.
In general I'm wondering whether it's feasible for binary operations to have left-hand evaluation flattened? I.e. eval the first arg of the AST node, all the way down, in a loop (until a non-compatible op is encountered, then recurse). Then apply the evaluation (here's the compiled znode of the first arg for the operation and here the 1..Nth args of the operation) in a loop.
This should be doable for most of binary operands including ->methodCallChaining().
For simple (non-shortcircuiting etc., like concat, maths etc.) binary operations this could also be applied to the righthand op.
At least that should cover all "common" cases which are not doing visible nesting with parenthesis.
If this is a viable approach (I have no idea, not tried), then I'd prefer seeing it fixed in PHP directly.
Seldaek commentedon Apr 7, 2022
I guess it could easily be split up in a few submethods/calls to reduce the stack depth. Please report it on the monolog-bundle though, I am not really maintaining that.
cmb69 commentedon Apr 7, 2022
@Seldaek, there is already symfony/monolog-bundle#412.
cmb69 commentedon Apr 7, 2022
@bwoebi, yeah, something like that could work. That would also solve issues like https://bugs.php.net/81580 (files with lots of string concatenation).
So reclassifying as feature request.
[-]Restarting" & "The connection was reset (net::ERR_CONNECTION_RESET)" when using monolog on XAMPP[/-][+]Try to avoid recursive compilation of binary ops[/+]Split configuration
Split configuration
arnaud-lb commentedon Dec 16, 2022
This should now be mitigated by #9104, as this will trigger a fatal error before overflowing the stack: