Find unused properties with dead code checks

Fixes #424

config.xsd

@@ -203,6 +203,7 @@
             <xs:element name="PossiblyUndefinedVariable" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="PossiblyUnusedMethod" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="PossiblyUnusedParam" type="IssueHandlerType" minOccurs="0" />
+            <xs:element name="PossiblyUnusedProperty" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="PropertyNotSetInConstructor" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="RawObjectIteration" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="RedundantCondition" type="IssueHandlerType" minOccurs="0" />
@@ -233,6 +234,7 @@
             <xs:element name="UnevaluatedCode" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="UnusedVariable" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="UnusedParam" type="IssueHandlerType" minOccurs="0" />
+            <xs:element name="UnusedProperty" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="UnusedClass" type="IssueHandlerType" minOccurs="0" />
             <xs:element name="UnusedMethod" type="IssueHandlerType" minOccurs="0" />
         </xs:choice>

psalm.xml

@@ -45,6 +45,18 @@
             </errorLevel>
         </UnusedClass>
 
+        <UnusedProperty>
+            <errorLevel type="info">
+                <file name="src/Psalm/FileManipulation/FunctionDocblockManipulator.php" />
+            </errorLevel>
+        </UnusedProperty>
+
+        <PossiblyUnusedProperty>
+            <errorLevel type="info">
+                <file name="src/Psalm/Storage/FunctionLikeStorage.php" />
+            </errorLevel>
+        </PossiblyUnusedProperty>
+
         <PossiblyUnusedMethod>
             <errorLevel type="suppress">
                 <directory name="tests" />

src/Psalm/Checker/ClassLikeChecker.php

@@ -88,11 +88,6 @@ abstract class ClassLikeChecker extends SourceChecker implements StatementsSourc
      */
     protected $fq_class_name;
 
-    /**
-     * @var bool
-     */
-    protected $has_custom_get = false;
-
     /**
      * The parent class
      *
@@ -100,16 +95,6 @@ abstract class ClassLikeChecker extends SourceChecker implements StatementsSourc
      */
     protected $parent_fq_class_name;
 
-    /**
-     * @var array<string, MethodChecker>
-     */
-    protected $method_checkers = [];
-
-    /**
-     * @var array<string, MethodChecker>
-     */
-    protected $property_types = [];
-
     /**
      * @var array<string, array<string, string>>|null
      */
@@ -1552,8 +1537,11 @@ abstract class ClassLikeChecker extends SourceChecker implements StatementsSourc
      *
      * @return bool
      */
-    public static function propertyExists(ProjectChecker $project_checker, $property_id)
+    public static function propertyExists(
-    {
+        ProjectChecker $project_checker,
+        $property_id,
+        CodeLocation $code_location = null
+    ) {
         // remove trailing backslash if it exists
         $property_id = preg_replace('/^\\\\/', '', $property_id);
 
@@ -1562,6 +1550,20 @@ abstract class ClassLikeChecker extends SourceChecker implements StatementsSourc
         $class_storage = $project_checker->classlike_storage_provider->get($fq_class_name);
 
         if (isset($class_storage->declaring_property_ids[$property_name])) {
+            if ($project_checker->collect_references && $code_location) {
+                $declaring_property_id = $class_storage->declaring_property_ids[$property_name];
+                list($declaring_property_class, $declaring_property_name) = explode('::$', $declaring_property_id);
+
+                $declaring_class_storage = $project_checker->classlike_storage_provider->get($declaring_property_class);
+                $declaring_property_storage = $declaring_class_storage->properties[$declaring_property_name];
+
+                if ($declaring_property_storage->referencing_locations === null) {
+                    $declaring_property_storage->referencing_locations = [];
+                }
+
+                $declaring_property_storage->referencing_locations[$code_location->file_path][] = $code_location;
+            }
+
             return true;
         }
 

src/Psalm/Checker/FileChecker.php

@@ -48,16 +48,6 @@ class FileChecker extends SourceChecker implements StatementsSource
      */
     protected $namespace_aliased_classes_flipped = [];
 
-    /**
-     * @var array<int, \PhpParser\Node\Stmt>
-     */
-    protected $preloaded_statements = [];
-
-    /**
-     * @var bool
-     */
-    public static $show_notices = true;
-
     /**
      * @var array<string, ClassLikeChecker>
      */
@@ -73,16 +63,6 @@ class FileChecker extends SourceChecker implements StatementsSource
      */
     protected $function_checkers = [];
 
-    /**
-     * @var array<int, NamespaceChecker>
-     */
-    protected $namespace_checkers = [];
-
-    /**
-     * @var array<string, bool>
-     */
-    private $included_file_paths = [];
-
     /**
      * @var ?Context
      */

src/Psalm/Checker/FunctionLikeChecker.php

@@ -59,11 +59,6 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
      */
     protected $is_static = false;
 
-    /**
-     * @var StatementsChecker|null
-     */
-    protected $statements_checker;
-
     /**
      * @var StatementsSource
      */
@@ -259,11 +254,6 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
 
         $statements_checker = new StatementsChecker($this);
 
-        // this increases memory, so only do it if running under this flag
-        if ($project_checker->infer_types_from_usage) {
-            $this->statements_checker = $statements_checker;
-        }
-
         $template_types = $storage->template_types;
 
         if ($class_storage && $class_storage->template_types) {
@@ -439,7 +429,23 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                     [],
                     false
                 );
-            } elseif (!$this->function instanceof Closure) {
+            } else {
+                $fleshed_out_signature_type = ExpressionChecker::fleshOutType(
+                    $project_checker,
+                    $storage->signature_return_type,
+                    $context->self,
+                    $cased_method_id
+                );
+
+                $fleshed_out_signature_type->check(
+                    $this,
+                    $storage->signature_return_type_location ?: $storage->return_type_location,
+                    $storage->suppressed_issues,
+                    [],
+                    false
+                );
+
+                if (!$this->function instanceof Closure) {
                     $fleshed_out_return_type = ExpressionChecker::fleshOutType(
                         $project_checker,
                         $storage->return_type,
@@ -478,14 +484,7 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                         )) {
                             return false;
                         }
-
+                    }
-                    $storage->signature_return_type->check(
-                        $this,
-                        $storage->return_type_location,
-                        $storage->suppressed_issues,
-                        [],
-                        false
-                    );
                 }
             }
         }

src/Psalm/Checker/MethodChecker.php

@@ -177,7 +177,6 @@ class MethodChecker extends FunctionLikeChecker
         $declaring_class = $method->getDeclaringClass();
 
         $storage->is_static = $method->isStatic();
-        $storage->namespace = $declaring_class->getNamespaceName();
         $class_storage->declaring_method_ids[$method_name] =
             $declaring_class->name . '::' . strtolower((string)$method->getName());
 

src/Psalm/Checker/NamespaceChecker.php

@@ -26,21 +26,6 @@ class NamespaceChecker extends SourceChecker implements StatementsSource
      */
     private $namespace_name;
 
-    /**
-     * @var array<int, FunctionChecker>
-     */
-    public $function_checkers = [];
-
-    /**
-     * @var array<int, ClassChecker>
-     */
-    public $class_checkers = [];
-
-    /**
-     * @var array<int, ClassChecker>
-     */
-    public $interface_checkers = [];
-
     /**
      * A lookup table for public namespace constants
      *

src/Psalm/Checker/ProjectChecker.php

@@ -9,8 +9,10 @@ use Psalm\FileManipulation\FunctionDocblockManipulator;
 use Psalm\Issue\CircularReference;
 use Psalm\Issue\PossiblyUnusedMethod;
 use Psalm\Issue\PossiblyUnusedParam;
+use Psalm\Issue\PossiblyUnusedProperty;
 use Psalm\Issue\UnusedClass;
 use Psalm\Issue\UnusedMethod;
+use Psalm\Issue\UnusedProperty;
 use Psalm\IssueBuffer;
 use Psalm\Provider\ClassLikeStorageProvider;
 use Psalm\Provider\FileProvider;
@@ -181,11 +183,6 @@ class ProjectChecker
      */
     private $scanned_files = [];
 
-    /**
-     * @var array<string, bool>
-     */
-    private $visited_classes = [];
-
     /**
      * @var array<string, FileChecker>
      */
@@ -1274,6 +1271,37 @@ class ProjectChecker
                 }
             }
         }
+
+        foreach ($classlike_storage->properties as $property_name => $property_storage) {
+            if (($property_storage->referencing_locations === null
+                    || count($property_storage->referencing_locations) === 0)
+                && (substr($property_name, 0, 2) !== '__' || $property_name === '__construct')
+                && $property_storage->location
+            ) {
+                $property_id = $classlike_storage->name . '::$' . $property_name;
+
+                if ($property_storage->visibility === ClassLikeChecker::VISIBILITY_PUBLIC) {
+                    if (IssueBuffer::accepts(
+                        new PossiblyUnusedProperty(
+                            'Cannot find public calls to property ' . $property_id,
+                            $property_storage->location
+                        ),
+                        $classlike_storage->suppressed_issues
+                    )) {
+                        // fall through
+                    }
+                } elseif (!isset($classlike_storage->declaring_method_ids['__get'])) {
+                    if (IssueBuffer::accepts(
+                        new UnusedProperty(
+                            'Property ' . $property_id . ' is never used',
+                            $property_storage->location
+                        )
+                    )) {
+                        // fall through
+                    }
+                }
+            }
+        }
     }
 
     /**

src/Psalm/Checker/Statements/Block/IfChecker.php

@@ -89,7 +89,6 @@ class IfChecker
         $context->inside_conditional = false;
 
         $if_scope = new IfScope();
-        $if_scope->has_elseifs = count($stmt->elseifs) > 0;
 
         $if_context = clone $context;
 

src/Psalm/Checker/Statements/Expression/FetchChecker.php

@@ -80,6 +80,8 @@ class FetchChecker
             return false;
         }
 
+        $project_checker = $statements_checker->getFileChecker()->project_checker;
+
         $stmt_var_id = ExpressionChecker::getVarId(
             $stmt->var,
             $statements_checker->getFQCLN(),
@@ -98,6 +100,25 @@ class FetchChecker
             // we don't need to check anything
             $stmt->inferredType = $context->vars_in_scope[$var_id];
 
+            if ($context->collect_references
+                && isset($stmt->var->inferredType)
+                && $stmt->var->inferredType->hasObjectType()
+                && is_string($stmt->name)
+            ) {
+                // log the appearance
+                foreach ($stmt->var->inferredType->getTypes() as $lhs_type_part) {
+                    if ($lhs_type_part instanceof TNamedObject) {
+                        $property_id = $lhs_type_part->value . '::$' . $stmt->name;
+
+                        ClassLikeChecker::propertyExists(
+                            $project_checker,
+                            $property_id,
+                            new CodeLocation($statements_checker->getSource(), $stmt)
+                        );
+                    }
+                }
+            }
+
             return null;
         }
 
@@ -208,8 +229,6 @@ class FetchChecker
                 continue;
             }
 
-            $project_checker = $statements_checker->getFileChecker()->project_checker;
-
             if (!ClassChecker::classExists($project_checker, $lhs_type_part->value)) {
                 if (InterfaceChecker::interfaceExists($project_checker, $lhs_type_part->value)) {
                     if (IssueBuffer::accepts(
@@ -260,7 +279,12 @@ class FetchChecker
                 }
             }
 
-            if (!ClassLikeChecker::propertyExists($project_checker, $property_id)) {
+            if (!ClassLikeChecker::propertyExists(
+                $project_checker,
+                $property_id,
+                $context->collect_references ? new CodeLocation($statements_checker->getSource(), $stmt) : null
+            )
+            ) {
                 if ($context->inside_isset) {
                     return;
                 }
@@ -699,16 +723,30 @@ class FetchChecker
                 $statements_checker
             );
 
+            $property_id = $fq_class_name . '::$' . $stmt->name;
+
             if ($var_id && $context->hasVariable($var_id)) {
                 // we don't need to check anything
                 $stmt->inferredType = $context->vars_in_scope[$var_id];
 
+                if ($context->collect_references) {
+                    // log the appearance
+                    ClassLikeChecker::propertyExists(
+                        $project_checker,
+                        $property_id,
+                        new CodeLocation($statements_checker->getSource(), $stmt)
+                    );
+                }
+
                 return null;
             }
 
-            $property_id = $fq_class_name . '::$' . $stmt->name;
+            if (!ClassLikeChecker::propertyExists(
-
+                $project_checker,
-            if (!ClassLikeChecker::propertyExists($project_checker, $property_id)) {
+                $property_id,
+                $context->collect_references ? new CodeLocation($statements_checker->getSource(), $stmt) : null
+            )
+            ) {
                 if (IssueBuffer::accepts(
                     new UndefinedPropertyFetch(
                         'Static property ' . $property_id . ' is not defined',

src/Psalm/Config.php

@@ -110,13 +110,6 @@ class Config
      */
     protected $base_dir;
 
-    /**
-     * The path to this config file
-     *
-     * @var string
-     */
-    public $file_path;
-
     /**
      * @var array<int, string>
      */
@@ -186,9 +179,6 @@ class Config
      */
     private $plugins = [];
 
-    /** @var array<string, bool> */
-    private $predefined_classlikes = [];
-
     /** @var array<string, mixed> */
     private $predefined_constants;
 
@@ -238,8 +228,6 @@ class Config
     {
         $config = new static();
 
-        $config->file_path = $file_path;
-
         $config->base_dir = $base_dir;
 
         $schema_path = dirname(dirname(__DIR__)) . '/config.xsd';

src/Psalm/Config/FileFilter.php

@@ -21,11 +21,6 @@ class FileFilter
      */
     protected $files_lowercase = [];
 
-    /**
-     * @var array<string>
-     */
-    protected $patterns = [];
-
     /**
      * @var bool
      */

src/Psalm/Issue/PossiblyUnusedProperty.php

@@ -0,0 +1,6 @@
+<?php
+namespace Psalm\Issue;
+
+class PossiblyUnusedProperty extends CodeIssue
+{
+}

src/Psalm/Issue/UnusedProperty.php

@@ -0,0 +1,6 @@
+<?php
+namespace Psalm\Issue;
+
+class UnusedProperty extends CodeIssue
+{
+}

src/Psalm/Scope/IfScope.php

@@ -46,11 +46,6 @@ class IfScope
      */
     public $negatable_if_types = null;
 
-    /**
-     * @var bool
-     */
-    public $has_elseifs;
-
     /**
      * @var array<int, Clause>
      */

src/Psalm/Storage/ClassLikeStorage.php

@@ -32,11 +32,6 @@ class ClassLikeStorage
      */
     public $populated = false;
 
-    /**
-     * @var bool
-     */
-    public $reflected = false;
-
     /**
      * @var bool
      */
@@ -62,11 +57,6 @@ class ClassLikeStorage
      */
     public $name;
 
-    /**
-     * @var array<string, string>
-     */
-    public $aliased_classes;
-
     /**
      * Is this class user-defined
      *

src/Psalm/Storage/FunctionLikeStorage.php

@@ -22,11 +22,6 @@ class FunctionLikeStorage
      */
     public $param_types = [];
 
-    /**
-     * @var string
-     */
-    public $namespace;
-
     /**
      * @var Type\Union|null
      */

src/Psalm/Storage/MethodStorage.php

@@ -10,16 +10,6 @@ class MethodStorage extends FunctionLikeStorage
      */
     public $is_static;
 
-    /**
-     * @var bool
-     */
-    public $reflected;
-
-    /**
-     * @var bool
-     */
-    public $registered;
-
     /**
      * @var int
      */

src/Psalm/Storage/PropertyStorage.php

@@ -45,4 +45,9 @@ class PropertyStorage
      * @var bool
      */
     public $deprecated = false;
+
+    /**
+     * @var array<string, array<int, CodeLocation>>|null
+     */
+    public $referencing_locations;
 }

src/Psalm/Type/Atomic/Fn.php

@@ -6,11 +6,6 @@ use Psalm\Type\Union;
 
 class Fn extends TNamedObject
 {
-    /**
-     * @var string
-     */
-    public $value = 'Closure';
-
     /**
      * @var array<int, FunctionLikeParameter>
      */
@@ -30,6 +25,7 @@ class Fn extends TNamedObject
      */
     public function __construct($value, array $params, Union $return_type)
     {
+        $this->value = 'Closure';
         $this->params = $params;
         $this->return_type = $return_type;
     }

src/Psalm/Visitor/DependencyFinderVisitor.php

@@ -41,11 +41,6 @@ class DependencyFinderVisitor extends PhpParser\NodeVisitorAbstract implements P
     /** @var Aliases */
     protected $file_aliases;
 
-    /**
-     * @var bool
-     */
-    protected $in_classlike = false;
-
     /**
      * @var string[]
      */

tests/ConfigTest.php

@@ -6,9 +6,6 @@ use Psalm\Config;
 
 class ConfigTest extends TestCase
 {
-    /** @var \PhpParser\Parser */
-    protected static $parser;
-
     /** @var TestConfig */
     protected static $config;
 

tests/TestCase.php

@@ -7,9 +7,6 @@ use Psalm\Checker\ProjectChecker;
 
 class TestCase extends BaseTestCase
 {
-    /** @var \PhpParser\Parser */
-    protected static $parser;
-
     /** @var TestConfig */
     protected static $config;
 

tests/TypeTest.php

@@ -958,6 +958,15 @@ class TypeTest extends TestCase
     public function providerFileCheckerInvalidCodeParse()
     {
         return [
+            'possiblyUndefinedVariable' => [
+                '<?php
+                    if (rand(0, 1)) {
+                        $a = 5;
+                    }
+
+                    echo $a;',
+                'error_message' => 'PossiblyUndefinedGlobalVariable',
+            ],
             'nullableMethodCall' => [
                 '<?php
                     class A {

tests/UnusedCodeTest.php

@@ -156,11 +156,16 @@ class UnusedCodeTest extends TestCase
                         public function modifyFoo(string $value) : void {
                             $this->value = $value;
                         }
+
+                        public function getFoo() : string {
+                            return $this->value;
+                        }
                     }
 
                     $m = new A();
                     $m->foo("value");
-                    $m->modifyFoo("value2");',
+                    $m->modifyFoo("value2");
+                    echo $m->getFoo();',
             ],
             'usedTraitMethod' => [
                 '<?php