ForbidVariableTypeOverwriting: deep generalization, generic SubtractableType (#35)

* ForbidVariableTypeOverwriting: deep generalization, generic SubtractableType

* Drop bad copypaste

Author: janedbal

src/Rule/ForbidVariableTypeOverwritingRule.php

@@ -16,9 +16,10 @@
 use PHPStan\Type\IntersectionType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\NullType;
-use PHPStan\Type\ObjectType;
+use PHPStan\Type\SubtractableType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\TypeTraverser;
 use PHPStan\Type\UnionType;
 use PHPStan\Type\VerbosityLevel;
 
@@ -53,8 +54,8 @@ public function processNode(Node $node, Scope $scope): array
             return [];
         }
 
-        $previousVariableType = $this->generalize($scope->getVariableType($variableName));
-        $newVariableType = $this->generalize($scope->getType($node->expr));
+        $previousVariableType = $this->generalizeDeeply($scope->getVariableType($variableName));
+        $newVariableType = $this->generalizeDeeply($scope->getType($node->expr));
 
         if ($this->isTypeToIgnore($previousVariableType) || $this->isTypeToIgnore($newVariableType)) {
             return [];
@@ -70,6 +71,13 @@ public function processNode(Node $node, Scope $scope): array
         return [];
     }
 
+    private function generalizeDeeply(Type $type): Type
+    {
+        return TypeTraverser::map($type, function (Type $traversedTyped, callable $traverse): Type {
+            return $traverse($this->generalize($traversedTyped));
+        });
+    }
+
     private function generalize(Type $type): Type
     {
         if (
@@ -113,8 +121,8 @@ private function removeNullAccessoryAndSubtractedTypes(Type $type): Type
             $type = TypeCombinator::intersect(...$newInnerTypes);
         }
 
-        if ($type instanceof ObjectType) {
-            $type = $type->changeSubtractedType(null);
+        if ($type instanceof SubtractableType) { // @phpstan-ignore-line ignore bc promise
+            $type = $type->getTypeWithoutSubtractedType(); // @phpstan-ignore-line ignore bc promise
         }
 
         return TypeCombinator::removeNull($type);

tests/Rule/data/ForbidAssignmentNotMatchingVarDocRule/code.php

@@ -126,6 +126,14 @@ public function returnArrayShape(): array
         return ['id' => 1, 'value' => 'foo'];
     }
 
+    /**
+     * @return iterable{ id: int, value: string }
+     */
+    public function returnIterableWithShape(): iterable
+    {
+        return ['id' => 1, 'value' => 'foo'];
+    }
+
     public function returnInt(): int
     {
         return 0;

tests/Rule/data/ForbidVariableTypeOverwritingRule/code.php

@@ -119,8 +119,15 @@ function testAdvancedTypesAreIgnored(
     $strictArray = ['string' => 'string'];
 }
 
-function testSubtractedTypeNotKept(ParentClass $someClass) {
+/**
+ * @param ParentClass $someClass
+ * @param mixed[] $strings
+ */
+function testSubtractedTypeNotKept(ParentClass $someClass, array $strings) {
     if (!$someClass instanceof ChildClass1) {
         $someClass = new ChildClass1();
     }
+
+    unset($strings[0]);
+    $strings = array_values($strings);
 }