Fix false-positive unused variable (#17)

Close #16

Author: Slamdunk

lib/UnusedVariableRule.php

@@ -5,10 +5,8 @@
 namespace SlamPhpStan;
 
 use PhpParser\Node;
-use PhpParser\Node\Expr\ArrayDimFetch;
 use PhpParser\Node\Expr\Assign;
 use PhpParser\Node\Expr\Closure;
-use PhpParser\Node\Expr\PropertyFetch;
 use PhpParser\Node\Expr\Variable;
 use PhpParser\Node\FunctionLike;
 use PhpParser\Node\Scalar\String_;
@@ -96,15 +94,16 @@ private function gatherVariablesUsage(Node $node, array & $unusedVariables, arra
                 if (\is_string($node->var->name) && ! isset($parameters[$node->var->name]) && ! isset(self::$globalVariables[$node->var->name])) {
                     $unusedVariables[$node->var->name] = $node->var;
                 }
-            } elseif ($node->var instanceof PropertyFetch) {
-                $this->gatherVariablesUsage($node->var->var, $unusedVariables, $usedVariables, $parameters);
-            } elseif ($node->var instanceof ArrayDimFetch) {
-                if ($node->var->var instanceof Node) {
+            } else {
+                if (\property_exists($node->var, 'var') && $node->var->var instanceof Node) {
                     $this->gatherVariablesUsage($node->var->var, $unusedVariables, $usedVariables, $parameters);
                 }
-                if ($node->var->dim instanceof Node) {
+                if (\property_exists($node->var, 'dim') && $node->var->dim instanceof Node) {
                     $this->gatherVariablesUsage($node->var->dim, $unusedVariables, $usedVariables, $parameters);
                 }
+                if (\property_exists($node->var, 'name') && $node->var->name instanceof Node) {
+                    $this->gatherVariablesUsage($node->var->name, $unusedVariables, $usedVariables, $parameters);
+                }
             }
         }
         if ($node instanceof Variable) {

tests/TestAsset/UnusedVariableRule/fixture.php

@@ -77,4 +77,26 @@ function foo($ref)
     $GLOBALS = null;
 }
 
+class Test
+{
+    function foo(array $numVals)
+    {
+        $arr = [
+            "1" => "propOne",
+            "2" => "propTwo",
+        ];
+
+        foreach ($numVals as $num => $v) {
+            $key = $arr[$num];
+            $this->{$key} = $v;
+
+            $key2 = $arr[$num];
+            $this->{$key2}();
+
+            $this->key = 1;
+            $this->key2();
+        }
+    }
+}
+
 $outsideFunctionVar = 1;