Fix narrowing to non-falsy-string when '' and '0' equality checks are in compound conditions

src/Analyser/ExprHandler/BooleanAndHandler.php

@@ -15,12 +15,16 @@
 use PHPStan\Analyser\MutatingScope;
 use PHPStan\Analyser\NodeScopeResolver;
 use PHPStan\Analyser\NoopNodeCallback;
+use PHPStan\Analyser\SpecifiedTypes;
+use PHPStan\Analyser\TypeSpecifier;
+use PHPStan\Analyser\TypeSpecifierContext;
 use PHPStan\DependencyInjection\AutowiredService;
 use PHPStan\Node\BooleanAndNode;
 use PHPStan\Type\BooleanType;
 use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\NeverType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 use function array_merge;
 
 /**
@@ -34,6 +38,7 @@ final class BooleanAndHandler implements ExprHandler
 
 	public function __construct(
 		private NodeScopeResolver $nodeScopeResolver,
+		private TypeSpecifier $typeSpecifier,
 	)
 	{
 	}
@@ -99,15 +104,42 @@ public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Ex
 
 		$nodeScopeResolver->callNodeCallbackWithExpression($nodeCallback, new BooleanAndNode($expr, $leftTruthyScope), $scope, $storage, $context);
 
+		$leftTruthySpecifiedTypes = $this->typeSpecifier->specifyTypesInCondition($scope, $expr->left, TypeSpecifierContext::createTruthy());
+
 		return new ExpressionResult(
 			$leftMergedWithRightScope,
 			hasYield: $leftResult->hasYield() || $rightResult->hasYield(),
 			isAlwaysTerminating: $leftResult->isAlwaysTerminating(),
 			throwPoints: array_merge($leftResult->getThrowPoints(), $rightResult->getThrowPoints()),
 			impurePoints: array_merge($leftResult->getImpurePoints(), $rightResult->getImpurePoints()),
-			truthyScopeCallback: static fn (): MutatingScope => $rightResult->getScope()->filterByTruthyValue($expr->right),
+			truthyScopeCallback: static fn (): MutatingScope => self::computeTruthyScope($rightResult->getScope(), $expr->right, $leftTruthySpecifiedTypes, $leftTruthyScope),
 			falseyScopeCallback: static fn (): MutatingScope => $leftMergedWithRightScope->filterByFalseyValue($expr),
 		);
 	}
 
+	private static function computeTruthyScope(
+		MutatingScope $rightScope,
+		Expr $rightExpr,
+		SpecifiedTypes $leftTruthySpecifiedTypes,
+		MutatingScope $leftTruthyScope,
+	): MutatingScope
+	{
+		$scope = $rightScope->filterByTruthyValue($rightExpr);
+
+		foreach ($leftTruthySpecifiedTypes->getSureNotTypes() as [$exprNode, $sureNotType]) {
+			if (!$leftTruthyScope->getType($exprNode)->equals($rightScope->getType($exprNode))) {
+				continue;
+			}
+
+			$exprType = $scope->getType($exprNode);
+			if (TypeCombinator::remove($exprType, $sureNotType) === $exprType) {
+				continue;
+			}
+
+			$scope = $scope->removeTypeFromExpression($exprNode, $sureNotType);
+		}
+
+		return $scope;
+	}
+
 }

src/Analyser/ExprHandler/BooleanOrHandler.php

@@ -13,12 +13,16 @@
 use PHPStan\Analyser\MutatingScope;
 use PHPStan\Analyser\NodeScopeResolver;
 use PHPStan\Analyser\NoopNodeCallback;
+use PHPStan\Analyser\SpecifiedTypes;
+use PHPStan\Analyser\TypeSpecifier;
+use PHPStan\Analyser\TypeSpecifierContext;
 use PHPStan\DependencyInjection\AutowiredService;
 use PHPStan\Node\BooleanOrNode;
 use PHPStan\Type\BooleanType;
 use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\NeverType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 use function array_merge;
 
 /**
@@ -32,6 +36,7 @@ final class BooleanOrHandler implements ExprHandler
 
 	public function __construct(
 		private NodeScopeResolver $nodeScopeResolver,
+		private TypeSpecifier $typeSpecifier,
 	)
 	{
 	}
@@ -83,15 +88,42 @@ public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Ex
 
 		$nodeScopeResolver->callNodeCallbackWithExpression($nodeCallback, new BooleanOrNode($expr, $leftFalseyScope), $scope, $storage, $context);
 
+		$leftFalseySpecifiedTypes = $this->typeSpecifier->specifyTypesInCondition($scope, $expr->left, TypeSpecifierContext::createFalsey());
+
 		return new ExpressionResult(
 			$leftMergedWithRightScope,
 			hasYield: $leftResult->hasYield() || $rightResult->hasYield(),
 			isAlwaysTerminating: $leftResult->isAlwaysTerminating(),
 			throwPoints: array_merge($leftResult->getThrowPoints(), $rightResult->getThrowPoints()),
 			impurePoints: array_merge($leftResult->getImpurePoints(), $rightResult->getImpurePoints()),
 			truthyScopeCallback: static fn (): MutatingScope => $leftMergedWithRightScope->filterByTruthyValue($expr),
-			falseyScopeCallback: static fn (): MutatingScope => $rightResult->getScope()->filterByFalseyValue($expr->right),
+			falseyScopeCallback: static fn (): MutatingScope => self::computeFalseyScope($rightResult->getScope(), $expr->right, $leftFalseySpecifiedTypes, $leftFalseyScope),
 		);
 	}
 
+	private static function computeFalseyScope(
+		MutatingScope $rightScope,
+		Expr $rightExpr,
+		SpecifiedTypes $leftFalseySpecifiedTypes,
+		MutatingScope $leftFalseyScope,
+	): MutatingScope
+	{
+		$scope = $rightScope->filterByFalseyValue($rightExpr);
+
+		foreach ($leftFalseySpecifiedTypes->getSureNotTypes() as [$exprNode, $sureNotType]) {
+			if (!$leftFalseyScope->getType($exprNode)->equals($rightScope->getType($exprNode))) {
+				continue;
+			}
+
+			$exprType = $scope->getType($exprNode);
+			if (TypeCombinator::remove($exprType, $sureNotType) === $exprType) {
+				continue;
+			}
+
+			$scope = $scope->removeTypeFromExpression($exprNode, $sureNotType);
+		}
+
+		return $scope;
+	}
+
 }

src/Type/TypeCombinator.php

@@ -64,8 +64,20 @@ public static function addNull(Type $type): Type
 	public static function remove(Type $fromType, Type $typeToRemove): Type
 	{
 		if ($typeToRemove instanceof UnionType) {
-			foreach ($typeToRemove->getTypes() as $unionTypeToRemove) {
-				$fromType = self::remove($fromType, $unionTypeToRemove);
+			$typesToRemove = $typeToRemove->getTypes();
+			$changed = true;
+			while ($changed && count($typesToRemove) > 0) {
+				$changed = false;
+				foreach ($typesToRemove as $key => $unionTypeToRemove) {
+					$newFromType = self::remove($fromType, $unionTypeToRemove);
+					if ($newFromType === $fromType) {
+						continue;
+					}
+
+					$fromType = $newFromType;
+					unset($typesToRemove[$key]);
+					$changed = true;
+				}
 			}
 			return $fromType;
 		}

tests/PHPStan/Analyser/nsrt/bug-9114.php

@@ -0,0 +1,47 @@
+<?php declare(strict_types = 1);
+
+namespace Bug9114;
+
+use function PHPStan\Testing\assertType;
+
+function foo(string $foo): void
+{
+	if ('' === $foo || '0' === $foo) {
+		throw new \Exception();
+	}
+	assertType('non-falsy-string', $foo);
+}
+
+function bar(string $foo): void
+{
+	if ('0' === $foo || '' === $foo) {
+		throw new \Exception();
+	}
+	assertType('non-falsy-string', $foo);
+}
+
+function baz(string $foo): void
+{
+	if ('0' === $foo) {
+		throw new \Exception();
+	}
+	assertType('string', $foo);
+	if ('' === $foo) {
+		throw new \Exception();
+	}
+	assertType('non-empty-string', $foo);
+}
+
+function qux(string $foo): void
+{
+	if ('' !== $foo && '0' !== $foo) {
+		assertType('non-falsy-string', $foo);
+	}
+}
+
+function quux(string $foo): void
+{
+	if ('0' !== $foo && '' !== $foo) {
+		assertType('non-falsy-string', $foo);
+	}
+}