Fix/issue 7144

[rajyan]

fixes phpstan/phpstan#7144

The root cause of this issue is expressed in this test dc5e865.

When specifying ArrayDimFetch type, it was relying only on $dimType, which can be any type as seen in the test.
The type to be specified should be only be a key existing in array`.

[ondrejmirtes]

I think that somehow, you need to handle multidimensional arrays too. The new error in CI is a false-positive: https://github.com/composer/composer/blob/3ae111140facdba8ae82adcd1085e4adfc7d715c/src/Composer/Util/Http/CurlDownloader.php#L230-L236

 ------ ----------------------------------------------------------------- 
  Line   src/Composer/Util/Http/CurlDownloader.php                        
 ------ ----------------------------------------------------------------- 
  232    Offset 'ssl' does not exist on array{http: array, ssl?: array}.  
  232    Offset 'ssl' does not exist on array{http: array, ssl?: array}.  
 ------ ----------------------------------------------------------------- 

[rajyan]

@ondrejmirtes
It is a regression, but is a expected behavior for me.
This PR could make the type of $option in foreach more specified (correct? I think) compared to the current playground result which lead to this regression.

To solve this case we need to implement type specification of isset with expr key.

Maybe I should solve these issues before this PR to avoid these kind of regressions (I'm looking into these issues but not easy to solve...)
phpstan/phpstan#6508
phpstan/phpstan#7000

[rajyan]

The goal for #1299 (comment) is to make $options[$type] specified by isset and also from $type === 'ssl' the array type can be array{http: array, ssl: array} (which looks not that easy to solve, because it is a result of multiple conditional expressions)

[ondrejmirtes]

I'm happy with the improved type inference of this PR, I just don't want this code https://github.com/composer/composer/blob/3ae111140facdba8ae82adcd1085e4adfc7d715c/src/Composer/Util/Http/CurlDownloader.php#L230-L236 to report these errors:

 ------ ----------------------------------------------------------------- 
  Line   src/Composer/Util/Http/CurlDownloader.php                        
 ------ ----------------------------------------------------------------- 
  232    Offset 'ssl' does not exist on array{http: array, ssl?: array}.  
  232    Offset 'ssl' does not exist on array{http: array, ssl?: array}.  
 ------ ----------------------------------------------------------------- 

Because the code involves expressions like isset($options[$type][$name]), this cannot be solved entirely by the typesystem. But I think it could be solved in NonexistentOffsetInArrayDimFetchRule / NonexistentOffsetInArrayDimFetchCheck. Because surely, isset($options[$type][$name]) makes $options[$type][$name] appear in MutatingScope::$moreSpecificTypes. So this rule/check could ask Scope::isSpecified() about this to prevent the false positive.

[rajyan]

I had investigated this issue in #1187.
The problem is, because type of array before and after isset doesn't change in these cases 83fe253, phpstan/phpstan#7000

Because surely, isset($options[$type][$name]) makes $options[$type][$name] appear in MutatingScope::$moreSpecificTypes.

this part is not true due to

phpstan-src/src/Analyser/MutatingScope.php

Lines 4358 to 4365 in 6f1535a

	if (
	!$expr instanceof Variable
	&& $exprType->equals($typeAfterRemove)
	&& !$exprType instanceof ErrorType
	&& !$exprType instanceof NeverType
	) {
	return $this;
	}

I tried to remove this line, but was not sure how to solve the failing tests.

I'll look into it again!:+1:

[ondrejmirtes]

The linked lines are supposed to be just an optimization that we might be able to remove I think. (But it's a long time since I touched these parts last time).