Improve explode return type precision

Author: staabm

src/Type/Php/ExplodeFunctionDynamicReturnTypeExtension.php

@@ -6,7 +6,6 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\Php\PhpVersion;
 use PHPStan\Reflection\FunctionReflection;
-use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\Accessory\NonEmptyArrayType;
 use PHPStan\Type\ArrayType;
@@ -41,32 +40,34 @@ public function getTypeFromFunctionCall(
 		Scope $scope,
 	): ?Type
 	{
-		if (count($functionCall->getArgs()) < 2) {
+		$args = $functionCall->getArgs();
+		if (count($args) < 2) {
 			return null;
 		}
 
-		$delimiterType = $scope->getType($functionCall->getArgs()[0]->value);
-		$isSuperset = (new ConstantStringType(''))->isSuperTypeOf($delimiterType);
-		if ($isSuperset->yes()) {
-			if ($this->phpVersion->getVersionId() >= 80000) {
+		$delimiterType = $scope->getType($args[0]->value);
+		$isEmptyString = (new ConstantStringType(''))->isSuperTypeOf($delimiterType);
+		if ($isEmptyString->yes()) {
+			if ($this->phpVersion->throwsTypeErrorForInternalFunctions()) {
 				return new NeverType();
 			}
 			return new ConstantBooleanType(false);
-		} elseif ($isSuperset->no()) {
-			$arrayType = AccessoryArrayListType::intersectWith(new ArrayType(new IntegerType(), new StringType()));
-			if (
-				!isset($functionCall->getArgs()[2])
-				|| IntegerRangeType::fromInterval(0, null)->isSuperTypeOf($scope->getType($functionCall->getArgs()[2]->value))->yes()
-			) {
-				return TypeCombinator::intersect($arrayType, new NonEmptyArrayType());
-			}
+		}
+
+		$returnType = AccessoryArrayListType::intersectWith(new ArrayType(new IntegerType(), new StringType()));
+		if (
+			!isset($args[2])
+			|| IntegerRangeType::fromInterval(0, null)->isSuperTypeOf($scope->getType($args[2]->value))->yes()
+		) {
+			$returnType = TypeCombinator::intersect($returnType, new NonEmptyArrayType());
+		}
 
-			return $arrayType;
+		if (!$this->phpVersion->throwsValueErrorForInternalFunctions() && $isEmptyString->maybe()) {
+			$returnType = TypeCombinator::union($returnType, new ConstantBooleanType(false));
 		}
 
-		$returnType = ParametersAcceptorSelector::selectSingle($functionReflection->getVariants())->getReturnType();
 		if ($delimiterType instanceof MixedType) {
-			return TypeUtils::toBenevolentUnion($returnType);
+			$returnType = TypeUtils::toBenevolentUnion($returnType);
 		}
 
 		return $returnType;

tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php

@@ -7292,15 +7292,15 @@ public function dataExplode(): array
 				'$sureFalse',
 			],
 			[
-				PHP_VERSION_ID < 80000 ? 'list<string>|false' : 'list<string>',
+				PHP_VERSION_ID < 80000 ? 'non-empty-list<string>|false' : 'non-empty-list<string>',
 				'$arrayOrFalse',
 			],
 			[
-				PHP_VERSION_ID < 80000 ? 'list<string>|false' : 'list<string>',
+				PHP_VERSION_ID < 80000 ? 'non-empty-list<string>|false' : 'non-empty-list<string>',
 				'$anotherArrayOrFalse',
 			],
 			[
-				PHP_VERSION_ID < 80000 ? '(list<string>|false)' : 'list<string>',
+				PHP_VERSION_ID < 80000 ? '(non-empty-list<string>|false)' : 'non-empty-list<string>',
 				'$benevolentArrayOrFalse',
 			],
 		];

tests/PHPStan/Analyser/data/bug-3961-php8.php

@@ -14,8 +14,8 @@ public function doFoo(string $v, string $d, $m): void
 		assertType('list<string>', explode('.', $v, -2));
 		assertType('non-empty-list<string>', explode('.', $v, 0));
 		assertType('non-empty-list<string>', explode('.', $v, 1));
-		assertType('list<string>', explode($d, $v));
-		assertType('list<string>', explode($m, $v));
+		assertType('non-empty-list<string>', explode($d, $v));
+		assertType('non-empty-list<string>', explode($m, $v));
 	}
 
 }

tests/PHPStan/Analyser/data/bug-3961.php

@@ -14,8 +14,8 @@ public function doFoo(string $v, string $d, $m): void
 		assertType('list<string>', explode('.', $v, -2));
 		assertType('non-empty-list<string>', explode('.', $v, 0));
 		assertType('non-empty-list<string>', explode('.', $v, 1));
-		assertType('list<string>|false', explode($d, $v));
-		assertType('(list<string>|false)', explode($m, $v));
+		assertType('non-empty-list<string>|false', explode($d, $v));
+		assertType('(non-empty-list<string>|false)', explode($m, $v));
 	}
 
 }