Variable property access on SimpleXMLElement

[ghispi]

Bug report

I'm not sure if this is bug or intended behavior but since SimpleXMLElement has special treatment as an Universal object crates, this should be handled as well, as there is no other way to access nodes having hyphen or other prohibited character.

As per https://www.php.net/manual/en/simplexml.examples-basic.php, example 3

Accessing elements within an XML document that contain characters not permitted under PHP's naming convention (e.g. the hyphen) can be accomplished by encapsulating the element name within braces and the apostrophe.

Code snippet that reproduces the problem

https://phpstan.org/r/93b6f5e2-cddb-4172-b42b-5017d0911fc4

Expected output

No error

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[VincentLanglet]

Hi @ondrejmirtes,

I'm interested in solving this issue.
Before implementing the solution, I'd like to know what do you prefer

Option 1:
All VariableRules should ignore constant string so the following code should be valid

$date = new \DateTime();
$date->{'format'}('Y');

Option 2:
The only non-reported constant string should be for SimpleXMLElement

$xml = new \ SimpleXMLElement();
$xml->{'foo-bar'};

[VincentLanglet]

After some investigations, I think it will be option 2 because the rule previously handled the SimpleXMLElement case.

• The rule was correct at first because it excludes universalObjectCratesClasses and SimpleXMLElement was one
  

  phpstan-strict-rules/src/Rules/VariableVariables/VariablePropertyFetchRule.php

  Line 52 in ed6fea0

  if ($this->isUniversalObjectCrate($this->reflectionProvider->getClass($referencedClass))) {

It's confirmed by the test which passed SimpleXMLElement

phpstan-strict-rules/tests/Rules/VariableVariables/VariablePropertyFetchRuleTest.php

Line 18 in ed6fea0

'SimpleXMLElement',

It's confirmed by the doc https://phpstan.org/config-reference#universal-object-crates which said SImpleXMLElement is included by default

Then, it was removed in this PHPStan commit phpstan/phpstan-src@56970a6
and now it has its own ExtendedPropertyReflection in https://github.com/phpstan/phpstan-src/blob/70572a17d592b6a7c148d9b2188408127378a4c2/src/Reflection/Php/SimpleXMLElementProperty.php#L17

That's why SimpleXMLElement is not handled anymore

[VincentLanglet]

I opened a PR to provide a behavior similar between SimpleXMLElement and Stdclass
#255