Implemented checks for use of void return of yield

dktapps · ondrejmirtes · commit da60c461c8b5 · 2020-08-30T20:20:23.000+02:00
this fixes #2873.
diff --git a/src/Rules/Generators/YieldTypeRule.php b/src/Rules/Generators/YieldTypeRule.php
@@ -12,6 +12,7 @@
 use PHPStan\Type\MixedType;
 use PHPStan\Type\NullType;
 use PHPStan\Type\VerbosityLevel;
+use PHPStan\Type\VoidType;
 
 /**
  * @implements \PHPStan\Rules\Rule<\PhpParser\Node\Expr\Yield_>
@@ -78,6 +79,9 @@ public function processNode(Node $node, Scope $scope): array
 				$valueType->describe($verbosityLevel)
 			))->build();
 		}
+		if ($scope->getType($node) instanceof VoidType && !$scope->isInFirstLevelStatement()) {
+			$messages[] = RuleErrorBuilder::message('Result of yield (void) is used.')->build();
+		}
 
 		return $messages;
 	}
diff --git a/tests/PHPStan/Rules/Generators/YieldTypeRuleTest.php b/tests/PHPStan/Rules/Generators/YieldTypeRuleTest.php
@@ -48,6 +48,14 @@ public function testRule(): void
 				'Generator expects value type array(0 => DateTime, 1 => DateTime, 2 => stdClass, 4 => DateTimeImmutable), array(DateTime, DateTime, stdClass, DateTimeImmutable) given.',
 				25,
 			],
+			[
+				'Result of yield (void) is used.',
+				137,
+			],
+			[
+				'Result of yield (void) is used.',
+				138,
+			],
 		]);
 	}
 
diff --git a/tests/PHPStan/Rules/Generators/data/yield.php b/tests/PHPStan/Rules/Generators/data/yield.php
@@ -119,3 +119,30 @@ function hash_to_alt_sequence2(iterable $hash): iterable
 	}
 
 }
+
+/**
+ * @return \Generator<int, int, int, void>
+ */
+function yieldWithIntSendType(){
+	yield 1;
+	$something = yield 1;
+	var_dump(yield 1);
+}
+
+/**
+ * @return \Generator<int, int, void, void>
+ */
+function yieldWithVoidSendType(){
+	yield 1;
+	$something = yield 1;
+	var_dump(yield 1);
+}
+
+/**
+ * @return \Generator<int, int>
+ */
+function yieldWithoutSendType(){
+	yield 1;
+	$something = yield 1;
+	var_dump(yield 1);
+}
