"Cannot instantiate" from|trait|abstract class from

[PhilETaylor]

Description

Im sorry but I cannot replicate this on demand. I cannot give you a test case and the details I have are very vague.

Basically, when trying to instantiate a concrete class (in production, which might mean this is when opcache is ramped up, or other caching in place), PHP will randomly throw an exception with the message in the format of the following - note this is the FULL message, the actual class is not mentioned and the message appears to be truncated.

"Cannot instantiate interface from"

"Cannot instantiate abstract class from"

"Cannot instantiate trait from"

The code for this appears to be somewhere near

php-src/Zend/zend_API.c

Line 1669 in adb45a6

static zend_always_inline zend_result _object_and_properties_init(zval *arg, zend_class_entry *class_type, HashTable *properties) /* {{{ */

Full details were first discovered when running Symfony in PHP 8.2 rc 2 in production (I know I know but someone has to lead :))

symfony/symfony#47653

A further report was then made by @julienchey in Monolog with PHP 8.1.0

Seldaek/monolog#1765

// Tagging @stof @mfn

PHP Version

Observed in 8.1.0/8.2.0rc2/8.2.0rc3

Operating System

Alpine Docker Container

[cmb69]

note this is the FULL message, the actual class is not mentioned and the message appears to be truncated.

It rather looks that ZSTR_VAL(class_type->name) is "from". There might be a memory corruption.

[PhilETaylor]

Just in case - this is the opcache config from production (which itself is a docker container)

[PhilETaylor]

This seems resolved in PHP 8.2 RC 6 released this week so "maybe" connected to something contained in https://news-web.php.net/php.internals/118991

[cmb69]

Possibly. Most important is that it is fixed. :)

[spideyfusion]

This issue still seems to be present in RC7. We just got hit by it in production.

The errors only happen the first time as opcache is being built, so in our case we were able to reproduce it by reloading FPM while the application was still serving requests.

opcache related configuration

opcache.enable=1
opcache.enable_cli=1
opcache.jit=disable
opcache.memory_consumption=256
opcache.max_accelerated_files=100000
opcache.validate_timestamps=0
opcache.enable_file_override=1

Error examples

• Uncaught Error: Cannot instantiate interface from
• Compile Error: Class AppBundle\ApiDoc\OpenApiResponseOK cannot extend interface tryFrom

Other notes

Our application is based on Symfony 5.4.16

[PhilETaylor]

Correct it is still present in RC7 - I have experienced it on every deployment but I did not want to reopen this until someone else had experienced it in case it was specific to my set up.

I'll reopen it now.

[PhilETaylor]

@cmb69 please re-add label for "Needs Triage"