Fix string concatenation with benevolent union type

src/Type/BenevolentUnionType.php

@@ -43,11 +43,18 @@ protected function unionTypes(callable $getType): Type
 		return TypeUtils::toBenevolentUnion(TypeCombinator::union(...$resultTypes));
 	}
 
-	protected function pickFromTypes(callable $getValues): array
+	protected function pickFromTypes(
+		callable $getValues,
+		callable $criteria,
+	): array
 	{
 		$values = [];
 		foreach ($this->getTypes() as $type) {
 			$innerValues = $getValues($type);
+			if ($innerValues === [] && $criteria($type)) {
+				return [];
+			}
+
 			foreach ($innerValues as $innerType) {
 				$values[] = $innerType;
 			}

src/Type/UnionType.php

@@ -124,27 +124,42 @@ public function getReferencedClasses(): array
 
 	public function getObjectClassNames(): array
 	{
-		return array_values(array_unique($this->pickFromTypes(static fn (Type $type) => $type->getObjectClassNames())));
+		return array_values(array_unique($this->pickFromTypes(
+			static fn (Type $type) => $type->getObjectClassNames(),
+			static fn (Type $type) => $type->isObject()->yes(),
+		)));
 	}
 
 	public function getObjectClassReflections(): array
 	{
-		return $this->pickFromTypes(static fn (Type $type) => $type->getObjectClassReflections());
+		return $this->pickFromTypes(
+			static fn (Type $type) => $type->getObjectClassReflections(),
+			static fn (Type $type) => $type->isObject()->yes(),
+		);
 	}
 
 	public function getArrays(): array
 	{
-		return $this->pickFromTypes(static fn (Type $type) => $type->getArrays());
+		return $this->pickFromTypes(
+			static fn (Type $type) => $type->getArrays(),
+			static fn (Type $type) => $type->isArray()->yes(),
+		);
 	}
 
 	public function getConstantArrays(): array
 	{
-		return $this->pickFromTypes(static fn (Type $type) => $type->getConstantArrays());
+		return $this->pickFromTypes(
+			static fn (Type $type) => $type->getConstantArrays(),
+			static fn (Type $type) => $type->isArray()->yes(),
+		);
 	}
 
 	public function getConstantStrings(): array
 	{
-		return $this->pickFromTypes(static fn (Type $type) => $type->getConstantStrings());
+		return $this->pickFromTypes(
+			static fn (Type $type) => $type->getConstantStrings(),
+			static fn (Type $type) => $type->isString()->yes(),
+		);
 	}
 
 	public function accepts(Type $type, bool $strictTypes): TrinaryLogic
@@ -719,7 +734,10 @@ public function shuffleArray(): Type
 
 	public function getEnumCases(): array
 	{
-		return $this->pickFromTypes(static fn (Type $type) => $type->getEnumCases());
+		return $this->pickFromTypes(
+			static fn (Type $type) => $type->getEnumCases(),
+			static fn (Type $type) => $type->isObject()->yes(),
+		);
 	}
 
 	public function isCallable(): TrinaryLogic
@@ -1073,15 +1091,19 @@ protected function unionTypes(callable $getType): Type
 	 */
 	protected function pickTypes(callable $getTypes): array
 	{
-		return $this->pickFromTypes($getTypes);
+		return $this->pickFromTypes($getTypes, static fn () => false);
 	}
 
 	/**
 	 * @template T
 	 * @param callable(Type $type): list<T> $getValues
+	 * @param callable(Type $type): bool $criteria
 	 * @return list<T>
 	 */
-	protected function pickFromTypes(callable $getValues): array
+	protected function pickFromTypes(
+		callable $getValues,
+		callable $criteria,
+	): array
 	{
 		$values = [];
 		foreach ($this->types as $type) {

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -764,6 +764,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6404.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6399.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-4357.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-10863.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5817.php');
 
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/array-chunk.php');

tests/PHPStan/Analyser/data/bug-10863.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace Bug10863;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+
+	/**
+	 * @param __benevolent<int|false> $b
+	 */
+	public function doFoo($b): void
+	{
+		assertType('non-falsy-string', '@' . $b);
+	}
+
+	/**
+	 * @param int|false $b
+	 */
+	public function doFoo2($b): void
+	{
+		assertType('non-falsy-string', '@' . $b);
+	}
+
+}