Support arrays with union value-types in implode()

[staabm]

Primary motivation: get rid of instanceof ConstantScalarType

closes phpstan/phpstan#11854

[phpstan-bot]

This pull request has been marked as ready for review.

[ondrejmirtes]

Ideally you'd count the combinations before generating them, it can explode as well.

[ondrejmirtes]

You're not counting the combinations properly. This is how I verified it:

diff --git a/src/Type/Php/ImplodeFunctionReturnTypeExtension.php b/src/Type/Php/ImplodeFunctionReturnTypeExtension.php
index 76afc963c..e45e0146a 100644
--- a/src/Type/Php/ImplodeFunctionReturnTypeExtension.php
+++ b/src/Type/Php/ImplodeFunctionReturnTypeExtension.php
@@ -22,6 +22,7 @@ use PHPStan\Type\TypeCombinator;
 use function count;
 use function implode;
 use function in_array;
+use function iterator_count;
 use const COUNT_RECURSIVE;
 
 final class ImplodeFunctionReturnTypeExtension implements DynamicFunctionReturnTypeExtension
@@ -124,10 +125,16 @@ final class ImplodeFunctionReturnTypeExtension implements DynamicFunctionReturnT
 				$arrayValues[] = $constScalars;
 			}
 
+			var_dump(count($strings) + count($arrayValues, COUNT_RECURSIVE));
+
 			if (count($strings) + count($arrayValues, COUNT_RECURSIVE) > InitializerExprTypeResolver::CALCULATE_SCALARS_LIMIT) {
 				return null;
 			}
 
+			var_dump(iterator_count(CombinationsHelper::combinations($arrayValues)));
+
+			var_dump('---');
+
 			$combinations = CombinationsHelper::combinations($arrayValues);
 			foreach ($combinations as $combination) {
 				$strings[] = new ConstantStringType(implode($separatorType->getValue(), $combination));

The output:

int(33)
int(8)
string(3) "---"
int(41)
int(8)
string(3) "---"

Expected output:

int(8)
int(8)
string(3) "---"
int(8)
int(8)
string(3) "---"

[ondrejmirtes]

Thank you!

[staabm]

this too generic type made me think about the general case and triggerd #3774