New world: single-pass expression processing through ExpressionResult callbacks

phpstan-baseline.neon

@@ -69,7 +69,7 @@ parameters:
 		-
 			rawMessage: Casting to string something that's already string.
 			identifier: cast.useless
-			count: 3
+			count: 5
 			path: src/Analyser/MutatingScope.php
 
 		-

src/Analyser/DirectInternalScopeFactory.php

@@ -38,6 +38,7 @@ public function __construct(
 		private $nodeCallback,
 		private ConstantResolver $constantResolver,
 		private bool $fiber = false,
+		private bool $resultAware = false,
 	)
 	{
 	}
@@ -64,6 +65,8 @@ public function create(
 		$className = MutatingScope::class;
 		if ($this->fiber) {
 			$className = FiberScope::class;
+		} elseif ($this->resultAware) {
+			$className = ResultAwareScope::class;
 		}
 
 		return new $className(
@@ -120,6 +123,27 @@ public function toFiberFactory(): InternalScopeFactory
 		);
 	}
 
+	public function toResultAwareFactory(): InternalScopeFactory
+	{
+		return new self(
+			$this->container,
+			$this->reflectionProvider,
+			$this->initializerExprTypeResolver,
+			$this->expressionTypeResolverExtensionRegistryProvider,
+			$this->exprPrinter,
+			$this->typeSpecifier,
+			$this->propertyReflectionFinder,
+			$this->parser,
+			$this->phpVersion,
+			$this->attributeReflectionFactory,
+			$this->configPhpVersion,
+			$this->nodeCallback,
+			$this->constantResolver,
+			false,
+			true,
+		);
+	}
+
 	public function toMutatingFactory(): InternalScopeFactory
 	{
 		return new self(

src/Analyser/ExprHandler/AssignOpHandler.php

@@ -53,6 +53,7 @@ public function supports(Expr $expr): bool
 
 	public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Expr $expr, MutatingScope $scope, ExpressionResultStorage $storage, callable $nodeCallback, ExpressionContext $context): ExpressionResult
 	{
+		$rhsExprResult = null;
 		$assignResult = $this->assignHandler->processAssignVar(
 			$nodeScopeResolver,
 			$scope,
@@ -62,7 +63,7 @@ public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Ex
 			$expr,
 			$nodeCallback,
 			$context,
-			static function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $context, $storage, $nodeScopeResolver): ExpressionResult {
+			static function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $context, $storage, $nodeScopeResolver, &$rhsExprResult): ExpressionResult {
 				$originalScope = $scope;
 				if ($expr instanceof Expr\AssignOp\Coalesce) {
 					$scope = $scope->filterByFalseyValue(
@@ -71,6 +72,7 @@ static function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $contex
 				}
 
 				$exprResult = $nodeScopeResolver->processExprNode($stmt, $expr->expr, $scope, $storage, $nodeCallback, $context->enterDeep());
+				$rhsExprResult = $exprResult;
 				if ($expr instanceof Expr\AssignOp\Coalesce) {
 					$nodeScopeResolver->storeBeforeScope($storage, $expr, $originalScope);
 					$isAlwaysTerminating = $exprResult->isAlwaysTerminating() && $originalScope->getType($expr->var)->isNull()->yes();
@@ -80,10 +82,20 @@ static function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $contex
 						$isAlwaysTerminating,
 						$exprResult->getThrowPoints(),
 						$exprResult->getImpurePoints(),
+						expr: $expr,
 					);
 				}
 
-				return $exprResult;
+				// the assigned value of an AssignOp is the op result, not the right side —
+				// wrap so processAssignVar falls back to the (guarded) legacy type of $expr
+				return new ExpressionResult(
+					$exprResult->getScope(),
+					$exprResult->hasYield(),
+					$exprResult->isAlwaysTerminating(),
+					$exprResult->getThrowPoints(),
+					$exprResult->getImpurePoints(),
+					expr: $expr,
+				);
 			},
 			$expr instanceof Expr\AssignOp\Coalesce,
 		);
@@ -94,13 +106,17 @@ static function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $contex
 		$throwPoints = $assignResult->getThrowPoints();
 		$impurePoints = $assignResult->getImpurePoints();
 		if (
-			($expr instanceof Expr\AssignOp\Div || $expr instanceof Expr\AssignOp\Mod) &&
-			!$scope->getType($expr->expr)->toNumber()->isSuperTypeOf(new ConstantIntegerType(0))->no()
+			($expr instanceof Expr\AssignOp\Div || $expr instanceof Expr\AssignOp\Mod)
+			&& $rhsExprResult !== null
+			&& !$rhsExprResult->getType()->toNumber()->isSuperTypeOf(new ConstantIntegerType(0))->no()
 		) {
 			$throwPoints[] = InternalThrowPoint::createExplicit($scope, new ObjectType(DivisionByZeroError::class), $expr, false);
 		}
 		if ($expr instanceof Expr\AssignOp\Concat) {
-			$toStringResult = $this->implicitToStringCallHelper->processImplicitToStringCall($expr->expr, $scope);
+			if ($rhsExprResult === null) {
+				throw new ShouldNotHappenException();
+			}
+			$toStringResult = $this->implicitToStringCallHelper->processImplicitToStringCall($expr->expr, $rhsExprResult->getType(), $scope);
 			$throwPoints = array_merge($throwPoints, $toStringResult->getThrowPoints());
 			$impurePoints = array_merge($impurePoints, $toStringResult->getImpurePoints());
 		}

src/Analyser/ExprHandler/BinaryOpHandler.php

@@ -94,8 +94,8 @@ public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Ex
 			$throwPoints[] = InternalThrowPoint::createExplicit($leftResult->getScope(), new ObjectType(DivisionByZeroError::class), $expr, false);
 		}
 		if ($expr instanceof BinaryOp\Concat) {
-			$leftToStringResult = $this->implicitToStringCallHelper->processImplicitToStringCall($expr->left, $scope);
-			$rightToStringResult = $this->implicitToStringCallHelper->processImplicitToStringCall($expr->right, $leftResult->getScope());
+			$leftToStringResult = $this->implicitToStringCallHelper->processImplicitToStringCall($expr->left, $leftResult->getType(), $scope);
+			$rightToStringResult = $this->implicitToStringCallHelper->processImplicitToStringCall($expr->right, $rightResult->getType(), $leftResult->getScope());
 			$throwPoints = array_merge($throwPoints, $leftToStringResult->getThrowPoints(), $rightToStringResult->getThrowPoints());
 			$impurePoints = array_merge($impurePoints, $leftToStringResult->getImpurePoints(), $rightToStringResult->getImpurePoints());
 		}

src/Analyser/ExprHandler/CastStringHandler.php

@@ -48,7 +48,7 @@ public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Ex
 		$impurePoints = $exprResult->getImpurePoints();
 		$throwPoints = $exprResult->getThrowPoints();
 
-		$toStringResult = $this->implicitToStringCallHelper->processImplicitToStringCall($expr->expr, $scope);
+		$toStringResult = $this->implicitToStringCallHelper->processImplicitToStringCall($expr->expr, $exprResult->getType(), $scope);
 		$throwPoints = array_merge($throwPoints, $toStringResult->getThrowPoints());
 		$impurePoints = array_merge($impurePoints, $toStringResult->getImpurePoints());