Add ArrayCountValuesDynamicReturnTypeExtension.

Author: mad-briller

src/Type/Php/ArrayCountValuesDynamicReturnTypeExtension.php

@@ -0,0 +1,59 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Php;
+
+use PhpParser\Node\Expr\FuncCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\DependencyInjection\AutowiredService;
+use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Type\ArrayType;
+use PHPStan\Type\DynamicFunctionReturnTypeExtension;
+use PHPStan\Type\ErrorType;
+use PHPStan\Type\IntegerRangeType;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+
+#[AutowiredService]
+final class ArrayCountValuesDynamicReturnTypeExtension implements DynamicFunctionReturnTypeExtension
+{
+
+	public function isFunctionSupported(FunctionReflection $functionReflection): bool
+	{
+		return $functionReflection->getName() === 'array_count_values';
+	}
+
+	public function getTypeFromFunctionCall(
+		FunctionReflection $functionReflection,
+		FuncCall $functionCall,
+		Scope $scope,
+	): ?Type
+	{
+		$args = $functionCall->getArgs();
+
+		if (!isset($args[0])) {
+			return null;
+		}
+
+		$inputType = $scope->getType($args[0]->value);
+
+		$arrayTypes = $inputType->getArrays();
+
+		$outputTypes = [];
+
+		foreach ($arrayTypes as $arrayType) {
+			$itemType = $arrayType->getItemType();
+
+			if ($itemType->toArrayKey() instanceof ErrorType) {
+				return new ErrorType();
+			}
+
+			$outputTypes[] = new ArrayType(
+				$itemType,
+				IntegerRangeType::fromInterval(0, null),
+			);
+		}
+
+		return TypeCombinator::union(...$outputTypes);
+	}
+
+}

tests/PHPStan/Analyser/nsrt/array-count-values.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace ArrayCountValues;
+
+use function PHPStan\Testing\assertType;
+
+$ints = array_count_values([1, 2, 2, 3]);
+
+assertType('array<1|2|3, int<0, max>>', $ints);
+
+$strings = array_count_values(['one', 'two', 'two', 'three']);
+
+assertType('array<\'one\'|\'three\'|\'two\', int<0, max>>', $strings);
+
+$strings = array_count_values([new \stdClass()]);
+
+assertType('*ERROR*', $strings);
+
+/**
+ * @return array<int, string|object>
+ */
+function returnsStringOrObjectArray(): array
+{
+
+}
+
+assertType('*ERROR*', array_count_values(returnsStringOrObjectArray()));