Infer return type never from closure

phpstan · Jan 23, 2021 · 98c8dd6 · 98c8dd6
1 parent 253178d
commit 98c8dd6
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Showing 2 changed files with 83 additions and 2 deletions.
diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
@@ -25,6 +25,7 @@
 use PhpParser\Node\Scalar\EncapsedStringPart;
 use PhpParser\Node\Scalar\LNumber;
 use PhpParser\Node\Scalar\String_;
+use PHPStan\Node\ExecutionEndNode;
 use PHPStan\Parser\Parser;
 use PHPStan\Reflection\ClassMemberReflection;
 use PHPStan\Reflection\ClassReflection;
@@ -1327,11 +1328,31 @@ private function resolveType(Expr $node): Type
 				$closureScope = $this->enterAnonymousFunctionWithoutReflection($node);
 				$closureReturnStatements = [];
 				$closureYieldStatements = [];
-				$this->nodeScopeResolver->processStmtNodes($node, $node->stmts, $closureScope, static function (Node $node, Scope $scope) use ($closureScope, &$closureReturnStatements, &$closureYieldStatements): void {
+				$closureExecutionEnds = [];
+				$this->nodeScopeResolver->processStmtNodes($node, $node->stmts, $closureScope, static function (Node $node, Scope $scope) use ($closureScope, &$closureReturnStatements, &$closureYieldStatements, &$closureExecutionEnds): void {
 					if ($scope->getAnonymousFunctionReflection() !== $closureScope->getAnonymousFunctionReflection()) {
 						return;
 					}
 
+					if ($node instanceof ExecutionEndNode) {
+						if ($node->getStatementResult()->isAlwaysTerminating()) {
+							foreach ($node->getStatementResult()->getExitPoints() as $exitPoint) {
+								if ($exitPoint->getStatement() instanceof Node\Stmt\Return_) {
+									continue;
+								}
+
+								$closureExecutionEnds[] = $node;
+								break;
+							}
+
+							if (count($node->getStatementResult()->getExitPoints()) === 0) {
+								$closureExecutionEnds[] = $node;
+							}
+						}
+
+						return;
+					}
+
 					if ($node instanceof Node\Stmt\Return_) {
 						$closureReturnStatements[] = [$node, $scope];
 					}
@@ -1355,8 +1376,15 @@ private function resolveType(Expr $node): Type
 				}
 
 				if (count($returnTypes) === 0) {
-					$returnType = new VoidType();
+					if (count($closureExecutionEnds) > 0 && !$hasNull) {
+						$returnType = new NeverType(true);
+					} else {
+						$returnType = new VoidType();
+					}
 				} else {
+					if (count($closureExecutionEnds) > 0) {
+						$returnTypes[] = new NeverType(true);
+					}
 					if ($hasNull) {
 						$returnTypes[] = new NullType();
 					}

diff --git a/tests/PHPStan/Analyser/data/closure-return-type.php b/tests/PHPStan/Analyser/data/closure-return-type.php
@@ -98,4 +98,57 @@ public function doFoo() {
 		assertType('1|2', $f());
 	}
 
+	/**
+	 * @return never
+	 */
+	public function returnNever(): void
+	{
+
+	}
+
+	public function doBaz(): void
+	{
+		$f = function() {
+			$this->returnNever();
+		};
+		assertType('*NEVER*', $f());
+
+		$f = function(): void {
+			$this->returnNever();
+		};
+		assertType('*NEVER*', $f());
+
+		$f = function() {
+			if (rand(0, 1)) {
+				return;
+			}
+
+			$this->returnNever();
+		};
+		assertType('void', $f());
+
+		$f = function(array $a) {
+			foreach ($a as $v) {
+				continue;
+			}
+
+			$this->returnNever();
+		};
+		assertType('*NEVER*', $f([]));
+
+		$f = function(array $a) {
+			foreach ($a as $v) {
+				$this->returnNever();
+			}
+		};
+		assertType('void', $f([]));
+
+		$f = function() {
+			foreach ([1, 2, 3] as $v) {
+				$this->returnNever();
+			}
+		};
+		assertType('*NEVER*', $f());
+	}
+
 }