Implement BinaryConcatHandler

Author: staabm

src/Analyser/Generator/ExprHandler/BinaryConcatHandler.php

@@ -0,0 +1,53 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Analyser\Generator\ExprHandler;
+
+use Generator;
+use PhpParser\Node\Expr;
+use PhpParser\Node\Stmt;
+use PHPStan\Analyser\ExpressionContext;
+use PHPStan\Analyser\Generator\ExprAnalysisRequest;
+use PHPStan\Analyser\Generator\ExprAnalysisResult;
+use PHPStan\Analyser\Generator\ExprHandler;
+use PHPStan\Analyser\Generator\GeneratorScope;
+use PHPStan\Analyser\SpecifiedTypes;
+use PHPStan\DependencyInjection\AutowiredService;
+use PHPStan\Reflection\InitializerExprTypeResolver;
+use function array_merge;
+
+/**
+ * @implements ExprHandler<Expr\BinaryOp\Concat>
+ */
+#[AutowiredService]
+final class BinaryConcatHandler implements ExprHandler
+{
+
+	public function __construct(private InitializerExprTypeResolver $initializerExprTypeResolver)
+	{
+	}
+
+	public function supports(Expr $expr): bool
+	{
+		return $expr instanceof Expr\BinaryOp\Concat;
+	}
+
+	public function analyseExpr(Stmt $stmt, Expr $expr, GeneratorScope $scope, ExpressionContext $context, ?callable $alternativeNodeCallback): Generator
+	{
+		$leftResult = yield new ExprAnalysisRequest($stmt, $expr->left, $scope, $context, $alternativeNodeCallback);
+		$rightResult = yield new ExprAnalysisRequest($stmt, $expr->right, $leftResult->scope, $context, $alternativeNodeCallback);
+
+		return new ExprAnalysisResult(
+			$this->initializerExprTypeResolver->resolveConcatType($leftResult->type, $rightResult->type),
+			$this->initializerExprTypeResolver->resolveConcatType($leftResult->nativeType, $rightResult->nativeType),
+			$rightResult->scope,
+			hasYield: $leftResult->hasYield || $rightResult->hasYield,
+			isAlwaysTerminating: $leftResult->isAlwaysTerminating || $rightResult->isAlwaysTerminating,
+			throwPoints: array_merge($leftResult->throwPoints, $rightResult->throwPoints),
+			impurePoints: array_merge($leftResult->impurePoints, $rightResult->impurePoints),
+			specifiedTruthyTypes: new SpecifiedTypes(),
+			specifiedFalseyTypes: new SpecifiedTypes(),
+			specifiedNullTypes: new SpecifiedTypes(),
+		);
+	}
+
+}

tests/PHPStan/Analyser/Generator/data/gnsr.php

@@ -82,6 +82,21 @@ public function doMul($a, $b, int $c, int $d): void
 		assertNativeType('int', $c * $d);
 	}
 
+	/**
+	 * @param string $a
+	 * @param string $b
+	 * @return void
+	 */
+	public function doConcat($a, $b, string $c, string $d): void
+	{
+		assertType('string', $a . $b);
+		assertNativeType('string', $a . $b);
+		assertType("'1a'", '1' . 'a');
+		assertNativeType("'1a'", '1' . 'a');
+		assertType('string', $c . $d);
+		assertNativeType('string', $c . $d);
+	}
+
 }
 
 function (): void {