psalm/src/Psalm/Internal/Analyzer/FunctionLikeAnalyzer.php

<?php
namespace Psalm\Internal\Analyzer;

use PhpParser;
use PhpParser\Node\Expr\Closure;
use PhpParser\Node\Stmt\ClassMethod;
use PhpParser\Node\Stmt\Function_;
use Psalm\Codebase;
use Psalm\Internal\Analyzer\FunctionLike\ReturnTypeAnalyzer;
use Psalm\Internal\Analyzer\FunctionLike\ReturnTypeCollector;
use Psalm\Internal\Analyzer\Statements\ExpressionAnalyzer;
use Psalm\CodeLocation;
use Psalm\Context;
use Psalm\Internal\FileManipulation\FunctionDocblockManipulator;
use Psalm\Issue\InvalidDocblockParamName;
use Psalm\Issue\InvalidParamDefault;
use Psalm\Issue\MismatchingDocblockParamType;
use Psalm\Issue\MissingClosureParamType;
use Psalm\Issue\MissingParamType;
use Psalm\Issue\MissingThrowsDocblock;
use Psalm\Issue\ReferenceConstraintViolation;
use Psalm\Issue\ReservedWord;
use Psalm\Issue\UnusedClosureParam;
use Psalm\Issue\UnusedParam;
use Psalm\IssueBuffer;
use Psalm\StatementsSource;
use Psalm\Storage\FunctionLikeParameter;
use Psalm\Storage\FunctionLikeStorage;
use Psalm\Storage\MethodStorage;
use Psalm\Type;
use Psalm\Type\Atomic\TNamedObject;
use function md5;
use function explode;
use function strtolower;
use function array_merge;
use function array_filter;
use function is_string;
use function array_key_exists;
use function substr;
use function strpos;
use function array_search;
use function array_keys;
use function end;
use function array_diff;
use Psalm\Internal\Taint\Source;

/**
 * @internal
 */
abstract class FunctionLikeAnalyzer extends SourceAnalyzer implements StatementsSource
{
    /**
     * @var Closure|Function_|ClassMethod
     */
    protected $function;

    /**
     * @var Codebase
     */
    protected $codebase;

    /**
     * @var array<string>
     */
    protected $suppressed_issues;

    /**
     * @var bool
     */
    protected $is_static = false;

    /**
     * @var StatementsSource
     */
    protected $source;

    /**
     * @var ?array<string, Type\Union>
     */
    protected $return_vars_in_scope = [];

    /**
     * @var ?array<string, bool>
     */
    protected $return_vars_possibly_in_scope = [];

    /**
     * @var Type\Union|null
     */
    private $local_return_type;

    /**
     * @var array<string, bool>
     */
    protected static $no_effects_hashes = [];

    /**
     * @var FunctionLikeStorage
     */
    protected $storage;

    /**
     * @param Closure|Function_|ClassMethod $function
     * @param SourceAnalyzer $source
     */
    protected function __construct($function, SourceAnalyzer $source, FunctionLikeStorage $storage)
    {
        $this->function = $function;
        $this->source = $source;
        $this->suppressed_issues = $source->getSuppressedIssues();
        $this->codebase = $source->getCodebase();
        $this->storage = $storage;
    }

    /**
     * @param Context       $context
     * @param Context|null  $global_context
     * @param bool          $add_mutations  whether or not to add mutations to this method
     * @param ?array<string, bool> $byref_uses
     *
     * @return false|null
     */
    public function analyze(
        Context $context,
        Context $global_context = null,
        $add_mutations = false,
        array $byref_uses = null
    ) {
        $storage = $this->storage;

        $function_stmts = $this->function->getStmts() ?: [];

        $hash = null;
        $real_method_id = null;

        $cased_method_id = null;

        $class_storage = null;

        if ($global_context) {
            foreach ($global_context->constants as $const_name => $var_type) {
                if (!$context->hasVariable($const_name)) {
                    $context->vars_in_scope[$const_name] = clone $var_type;
                }
            }
        }

        $codebase = $this->codebase;
        $project_analyzer = $this->getProjectAnalyzer();

        $implemented_docblock_param_types = [];

        $classlike_storage_provider = $codebase->classlike_storage_provider;

        if ($codebase->track_unused_suppressions && !isset($storage->suppressed_issues[0])) {
            foreach ($storage->suppressed_issues as $offset => $issue_name) {
                IssueBuffer::addUnusedSuppression($this->getFilePath(), $offset, $issue_name);
            }
        }

        $overridden_method_ids = [];

        if ($this->function instanceof ClassMethod) {
            if (!$storage instanceof MethodStorage) {
                throw new \UnexpectedValueException('$storage must be MethodStorage');
            }

            $real_method_id = (string)$this->getMethodId();

            $method_id = (string)$this->getMethodId($context->self);

            if ($add_mutations) {
                $hash = md5($real_method_id . '::' . $context->getScopeSummary());

                // if we know that the function has no effects on vars, we don't bother rechecking
                if (isset(self::$no_effects_hashes[$hash])) {
                    return null;
                }
            } elseif ($context->self) {
                $context->vars_in_scope['$this'] = new Type\Union([new TNamedObject($context->self)]);
                $context->vars_possibly_in_scope['$this'] = true;
            }

            $fq_class_name = (string)$context->self;

            $class_storage = $classlike_storage_provider->get($fq_class_name);

            if ($class_storage->has_visitor_issues) {
                return null;
            }

            $cased_method_id = $fq_class_name . '::' . $storage->cased_name;

            $overridden_method_ids = $codebase->methods->getOverriddenMethodIds($method_id);

            if ($this->function->name->name === '__construct') {
                $context->inside_constructor = true;
            }

            $codeLocation = new CodeLocation(
                $this,
                $this->function,
                null,
                true
            );

            if ($overridden_method_ids
                && $this->function->name->name !== '__construct'
                && !$context->collect_initializations
                && !$context->collect_mutations
            ) {
                foreach ($overridden_method_ids as $overridden_method_id) {
                    $parent_method_storage = $codebase->methods->getStorage($overridden_method_id);

                    list($overridden_fq_class_name) = explode('::', $overridden_method_id);

                    $parent_storage = $classlike_storage_provider->get($overridden_fq_class_name);

                    $implementer_visibility = $storage->visibility;

                    $implementer_appearing_method_id = $codebase->methods->getAppearingMethodId($cased_method_id);
                    $implementer_declaring_method_id = $real_method_id;

                    if ($implementer_appearing_method_id
                        && $implementer_appearing_method_id !== $implementer_declaring_method_id
                    ) {
                        list($appearing_fq_class_name, $appearing_method_name) = explode(
                            '::',
                            $implementer_appearing_method_id
                        );

                        $appearing_class_storage = $classlike_storage_provider->get(
                            $appearing_fq_class_name
                        );

                        if (isset($appearing_class_storage->trait_visibility_map[$appearing_method_name])) {
                            $implementer_visibility
                                = $appearing_class_storage->trait_visibility_map[$appearing_method_name];
                        }
                    }

                    // we've already checked this in the class checker
                    if (!isset($class_storage->class_implements[strtolower($overridden_fq_class_name)])) {
                        MethodAnalyzer::compareMethods(
                            $codebase,
                            $class_storage,
                            $parent_storage,
                            $storage,
                            $parent_method_storage,
                            $fq_class_name,
                            $implementer_visibility,
                            $codeLocation,
                            $storage->suppressed_issues
                        );
                    }

                    foreach ($parent_method_storage->params as $i => $guide_param) {
                        if ($guide_param->type
                            && (!$guide_param->signature_type
                                || ($guide_param->signature_type !== $guide_param->type
                                    && $storage->inheritdoc)
                                || !$parent_storage->user_defined
                            )
                        ) {
                            if (!isset($implemented_docblock_param_types[$i])) {
                                $implemented_docblock_param_types[$i] = $guide_param->type;
                            }
                        }
                    }
                }
            }

            MethodAnalyzer::checkMethodSignatureMustOmitReturnType($storage, $codeLocation);

            $context->calling_method_id = strtolower($method_id);
        } elseif ($this->function instanceof Function_) {
            $cased_method_id = $this->function->name->name;
        } else { // Closure
            if ($storage->return_type) {
                $closure_return_type = ExpressionAnalyzer::fleshOutType(
                    $codebase,
                    $storage->return_type,
                    $context->self,
                    $context->self,
                    $this->getParentFQCLN()
                );
            } else {
                $closure_return_type = Type::getMixed();
            }

            /** @var PhpParser\Node\Expr\Closure $this->function */
            $this->function->inferredType = new Type\Union([
                new Type\Atomic\TFn(
                    'Closure',
                    $storage->params,
                    $closure_return_type
                ),
            ]);
        }

        $this->suppressed_issues = $this->getSource()->getSuppressedIssues() + $storage->suppressed_issues;

        if ($storage instanceof MethodStorage && $storage->is_static) {
            $this->is_static = true;
        }

        $statements_analyzer = new StatementsAnalyzer($this);

        if ($byref_uses) {
            $statements_analyzer->setByRefUses($byref_uses);
        }

        if ($storage->template_types) {
            foreach ($storage->template_types as $param_name => $_) {
                $fq_classlike_name = Type::getFQCLNFromString(
                    $param_name,
                    $this->getAliases()
                );

                if ($codebase->classOrInterfaceExists($fq_classlike_name)) {
                    if (IssueBuffer::accepts(
                        new ReservedWord(
                            'Cannot use ' . $param_name . ' as template name since the class already exists',
                            new CodeLocation($this, $this->function),
                            'resource'
                        ),
                        $this->getSuppressedIssues()
                    )) {
                        // fall through
                    }
                }
            }
        }

        $template_types = $storage->template_types;

        if ($class_storage && $class_storage->template_types) {
            $template_types = array_merge($template_types ?: [], $class_storage->template_types);
        }

        $params = $storage->params;

        if ($storage instanceof MethodStorage) {
            $non_null_param_types = array_filter(
                $storage->params,
                /** @return bool */
                function (FunctionLikeParameter $p) {
                    return $p->type !== null && $p->has_docblock_type;
                }
            );
        } else {
            $non_null_param_types = array_filter(
                $storage->params,
                /** @return bool */
                function (FunctionLikeParameter $p) {
                    return $p->type !== null;
                }
            );
        }

        if ($storage instanceof MethodStorage
            && is_string($cased_method_id)
            && $overridden_method_ids
        ) {
            $types_without_docblocks = array_filter(
                $storage->params,
                /** @return bool */
                function (FunctionLikeParameter $p) {
                    return !$p->type || !$p->has_docblock_type;
                }
            );

            if ($types_without_docblocks) {
                $params = $codebase->methods->getMethodParams($cased_method_id, $this);
            }
        }

        $check_stmts = true;

        if ($codebase->alter_code) {
            foreach ($this->function->params as $param) {
                $param_name_node = null;

                if ($param->type instanceof PhpParser\Node\Name) {
                    $param_name_node = $param->type;
                } elseif ($param->type instanceof PhpParser\Node\NullableType
                    && $param->type->type instanceof PhpParser\Node\Name
                ) {
                    $param_name_node = $param->type->type;
                }

                if ($param_name_node) {
                    $resolved_name = ClassLikeAnalyzer::getFQCLNFromNameObject($param_name_node, $this->getAliases());

                    $parent_fqcln = $this->getParentFQCLN();

                    if ($resolved_name === 'self' && $context->self) {
                        $resolved_name = (string) $context->self;
                    } elseif ($resolved_name === 'parent' && $parent_fqcln) {
                        $resolved_name = $parent_fqcln;
                    }

                    $codebase->classlikes->handleClassLikeReferenceInMigration(
                        $codebase,
                        $this,
                        $param_name_node,
                        $resolved_name,
                        $context->calling_method_id
                    );
                }
            }

            if ($this->function->returnType) {
                $return_name_node = null;

                if ($this->function->returnType instanceof PhpParser\Node\Name) {
                    $return_name_node = $this->function->returnType;
                } elseif ($this->function->returnType instanceof PhpParser\Node\NullableType
                    && $this->function->returnType->type instanceof PhpParser\Node\Name
                ) {
                    $return_name_node = $this->function->returnType->type;
                }

                if ($return_name_node) {
                    $resolved_name = ClassLikeAnalyzer::getFQCLNFromNameObject($return_name_node, $this->getAliases());

                    $parent_fqcln = $this->getParentFQCLN();

                    if ($resolved_name === 'self' && $context->self) {
                        $resolved_name = (string) $context->self;
                    } elseif ($resolved_name === 'parent' && $parent_fqcln) {
                        $resolved_name = $parent_fqcln;
                    }

                    $codebase->classlikes->handleClassLikeReferenceInMigration(
                        $codebase,
                        $this,
                        $return_name_node,
                        $resolved_name,
                        $context->calling_method_id
                    );
                }
            }

            if ($storage->return_type
                && $storage->return_type_location
                && $storage->return_type_location !== $storage->signature_return_type_location
            ) {
                $replace_type = ExpressionAnalyzer::fleshOutType(
                    $codebase,
                    $storage->return_type,
                    $context->self,
                    $context->self,
                    $this->getParentFQCLN(),
                    false
                );

                $codebase->classlikes->handleDocblockTypeInMigration(
                    $codebase,
                    $this,
                    $replace_type,
                    $storage->return_type_location,
                    $context->calling_method_id
                );
            }

            foreach ($params as $function_param) {
                if ($function_param->type
                    && $function_param->type_location
                    && $function_param->type_location !== $function_param->signature_type_location
                    && $function_param->type_location->file_path === $this->getFilePath()
                ) {
                    $replace_type = ExpressionAnalyzer::fleshOutType(
                        $codebase,
                        $function_param->type,
                        $context->self,
                        $context->self,
                        $this->getParentFQCLN(),
                        false
                    );

                    $codebase->classlikes->handleDocblockTypeInMigration(
                        $codebase,
                        $this,
                        $replace_type,
                        $function_param->type_location,
                        $context->calling_method_id
                    );
                }
            }
        }

        foreach ($codebase->methods_to_rename as $original_method_id => $new_method_name) {
            if ($this->function instanceof ClassMethod
                && strtolower($this->getMethodId()) === $original_method_id
            ) {
                $file_manipulations = [
                    new \Psalm\FileManipulation(
                        (int) $this->function->name->getAttribute('startFilePos'),
                        (int) $this->function->name->getAttribute('endFilePos') + 1,
                        $new_method_name
                    )
                ];

                \Psalm\Internal\FileManipulation\FileManipulationBuffer::add(
                    $this->getFilePath(),
                    $file_manipulations
                );
            }
        }

        foreach ($params as $offset => $function_param) {
            $signature_type = $function_param->signature_type;
            $signature_type_location = $function_param->signature_type_location;

            if ($signature_type && $signature_type_location && $signature_type->hasObjectType()) {
                list($start, $end) = $signature_type_location->getSelectionBounds();

                $codebase->analyzer->addOffsetReference(
                    $this->getFilePath(),
                    $start,
                    $end,
                    (string) $signature_type
                );
            }

            if ($signature_type) {
                $signature_type = ExpressionAnalyzer::fleshOutType(
                    $codebase,
                    $signature_type,
                    $context->self,
                    $context->self,
                    $this->getParentFQCLN()
                );
            }

            if ($function_param->type) {
                $is_signature_type = $function_param->type === $function_param->signature_type;

                if ($is_signature_type
                    && $storage instanceof MethodStorage
                    && $storage->inheritdoc
                    && isset($implemented_docblock_param_types[$offset])
                ) {
                    $param_type = clone $implemented_docblock_param_types[$offset];
                } else {
                    $param_type = clone $function_param->type;
                }

                $param_type = ExpressionAnalyzer::fleshOutType(
                    $codebase,
                    $param_type,
                    $context->self,
                    $context->self,
                    $this->getParentFQCLN()
                );

                if ($function_param->type_location) {
                    if ($param_type->check(
                        $this,
                        $function_param->type_location,
                        $storage->suppressed_issues,
                        [],
                        false,
                        $this->function instanceof ClassMethod
                            && strtolower($this->function->name->name) !== '__construct'
                    ) === false) {
                        $check_stmts = false;
                    }
                }
            } else {
                if (!$non_null_param_types && isset($implemented_docblock_param_types[$offset])) {
                    $param_type = clone $implemented_docblock_param_types[$offset];

                    $param_type = ExpressionAnalyzer::fleshOutType(
                        $codebase,
                        $param_type,
                        $context->self,
                        $context->self,
                        $this->getParentFQCLN()
                    );
                } else {
                    $param_type = Type::getMixed();
                }
            }

            $var_type = $param_type;

            if ($function_param->is_variadic) {
                $var_type = new Type\Union([
                    new Type\Atomic\TArray([
                        Type::getInt(),
                        $param_type,
                    ]),
                ]);
            }

            if ($cased_method_id && $codebase->taint) {
                $type_source = Source::getForMethodArgument(
                    $cased_method_id,
                    $offset,
                    $function_param->location,
                    null
                );
                $var_type->sources = [$type_source];

                if ($tainted_source = $codebase->taint->hasExistingSource($type_source)) {
                    $var_type->tainted = $tainted_source->taint;
                    $type_source->taint = $tainted_source->taint;
                }
            }

            $context->vars_in_scope['$' . $function_param->name] = $var_type;
            $context->vars_possibly_in_scope['$' . $function_param->name] = true;

            if ($context->collect_references && $function_param->location) {
                $context->unreferenced_vars['$' . $function_param->name] = [
                    $function_param->location->getHash() => $function_param->location
                ];
            }

            /**
             * @var PhpParser\Node\Param
             */
            $parser_param = $this->function->getParams()[$offset];

            if (!$function_param->type_location || !$function_param->location) {
                if ($parser_param->default) {
                    ExpressionAnalyzer::analyze($statements_analyzer, $parser_param->default, $context);
                }

                continue;
            }

            if ($signature_type) {
                $union_comparison_result = new TypeComparisonResult();

                if (!TypeAnalyzer::isContainedBy(
                    $codebase,
                    $param_type,
                    $signature_type,
                    false,
                    false,
                    $union_comparison_result
                ) && !$union_comparison_result->type_coerced_from_mixed
                ) {
                    if ($codebase->alter_code
                        && isset($project_analyzer->getIssuesToFix()['MismatchingDocblockParamType'])
                    ) {
                        $this->addOrUpdateParamType($project_analyzer, $function_param->name, $signature_type, true);

                        continue;
                    }

                    if (IssueBuffer::accepts(
                        new MismatchingDocblockParamType(
                            'Parameter $' . $function_param->name . ' has wrong type \'' . $param_type .
                                '\', should be \'' . $signature_type . '\'',
                            $function_param->type_location
                        ),
                        $storage->suppressed_issues
                    )) {
                        return false;
                    }

                    if ($signature_type->check(
                        $this,
                        $function_param->type_location,
                        $storage->suppressed_issues,
                        [],
                        false
                    ) === false) {
                        $check_stmts = false;
                    }

                    continue;
                }
            }

            if ($parser_param->default) {
                ExpressionAnalyzer::analyze($statements_analyzer, $parser_param->default, $context);

                $default_type = isset($parser_param->default->inferredType)
                    ? $parser_param->default->inferredType
                    : null;

                if ($default_type
                    && !$default_type->hasMixed()
                    && !TypeAnalyzer::isContainedBy(
                        $codebase,
                        $default_type,
                        $param_type,
                        false,
                        false,
                        null,
                        true
                    )
                ) {
                    if (IssueBuffer::accepts(
                        new InvalidParamDefault(
                            'Default value type ' . $default_type . ' for argument ' . ($offset + 1)
                                . ' of method ' . $cased_method_id
                                . ' does not match the given type ' . $param_type,
                            $function_param->type_location
                        )
                    )) {
                        // fall through
                    }
                }
            }

            if ($template_types) {
                $substituted_type = clone $param_type;
                if ($substituted_type->check(
                    $this->source,
                    $function_param->type_location,
                    $this->suppressed_issues,
                    [],
                    false
                ) === false) {
                    $check_stmts = false;
                }
            } else {
                if ($param_type->isVoid()) {
                    if (IssueBuffer::accepts(
                        new ReservedWord(
                            'Parameter cannot be void',
                            $function_param->type_location,
                            'void'
                        ),
                        $this->suppressed_issues
                    )) {
                        // fall through
                    }
                }

                if ($param_type->check(
                    $this->source,
                    $function_param->type_location,
                    $this->suppressed_issues,
                    [],
                    false
                ) === false) {
                    $check_stmts = false;
                }
            }

            if ($codebase->collect_references) {
                if ($function_param->type_location !== $function_param->signature_type_location &&
                    $function_param->signature_type_location &&
                    $function_param->signature_type
                ) {
                    if ($function_param->signature_type->check(
                        $this->source,
                        $function_param->signature_type_location,
                        $this->suppressed_issues,
                        [],
                        false
                    ) === false) {
                        $check_stmts = false;
                    }
                }
            }

            if ($function_param->by_ref) {
                // register by ref params as having been used, to avoid false positives
                // @todo change the assignment analysis *just* for byref params
                // so that we don't have to do this
                $context->hasVariable('$' . $function_param->name);
            }

            $statements_analyzer->registerVariable(
                '$' . $function_param->name,
                $function_param->location,
                null
            );
        }

        if ($storage->pure) {
            $context->pure = true;
        }

        if ($storage->unused_docblock_params) {
            foreach ($storage->unused_docblock_params as $param_name => $param_location) {
                if (IssueBuffer::accepts(
                    new InvalidDocblockParamName(
                        'Incorrect param name $' . $param_name . ' in docblock for ' . $cased_method_id,
                        $param_location
                    )
                )) {
                }
            }
        }

        if (ReturnTypeAnalyzer::checkReturnType(
            $this->function,
            $project_analyzer,
            $this,
            $storage,
            $context
        ) === false) {
            $check_stmts = false;
        }

        if (!$check_stmts) {
            return false;
        }

        if ($context->collect_initializations || $context->collect_mutations) {
            $statements_analyzer->addSuppressedIssues([
                'DocblockTypeContradiction',
                'InvalidReturnStatement',
                'RedundantCondition',
                'RedundantConditionGivenDocblockType',
                'TypeDoesNotContainNull',
                'TypeDoesNotContainType',
                'LoopInvalidation',
            ]);

            if ($context->collect_initializations) {
                $statements_analyzer->addSuppressedIssues([
                    'UndefinedInterfaceMethod',
                    'UndefinedMethod',
                    'PossiblyUndefinedMethod',
                ]);
            }
        }

        $statements_analyzer->analyze($function_stmts, $context, $global_context, true);

        $this->examineParamTypes($statements_analyzer, $context, $codebase);

        foreach ($storage->params as $offset => $function_param) {
            // only complain if there's no type defined by a parent type
            if (!$function_param->type
                && $function_param->location
                && !isset($implemented_docblock_param_types[$offset])
            ) {
                if ($this->function instanceof Closure) {
                    IssueBuffer::accepts(
                        new MissingClosureParamType(
                            'Parameter $' . $function_param->name . ' has no provided type',
                            $function_param->location
                        ),
                        $storage->suppressed_issues + $this->getSuppressedIssues()
                    );
                } else {
                    IssueBuffer::accepts(
                        new MissingParamType(
                            'Parameter $' . $function_param->name . ' has no provided type',
                            $function_param->location
                        ),
                        $storage->suppressed_issues + $this->getSuppressedIssues()
                    );
                }
            }
        }

        if ($storage->signature_return_type && $storage->signature_return_type_location) {
            list($start, $end) = $storage->signature_return_type_location->getSelectionBounds();

            $codebase->analyzer->addOffsetReference(
                $this->getFilePath(),
                $start,
                $end,
                (string) $storage->signature_return_type
            );
        }

        if ($this->function instanceof Closure) {
            $this->verifyReturnType(
                $statements_analyzer,
                $storage->return_type,
                $this->source->getFQCLN(),
                $storage->return_type_location,
                $global_context && $global_context->inside_call
            );

            $closure_yield_types = [];

            $ignore_nullable_issues = false;
            $ignore_falsable_issues = false;

            $closure_return_types = ReturnTypeCollector::getReturnTypes(
                $this->function->stmts,
                $closure_yield_types,
                $ignore_nullable_issues,
                $ignore_falsable_issues,
                true
            );

            if ($closure_return_types) {
                $closure_return_type = new Type\Union($closure_return_types);

                if (!$storage->return_type
                    || $storage->return_type->hasMixed()
                    || TypeAnalyzer::isContainedBy(
                        $codebase,
                        $closure_return_type,
                        $storage->return_type
                    )
                ) {
                    if ($this->function->inferredType) {
                        /** @var Type\Atomic\TFn */
                        $closure_atomic = $this->function->inferredType->getTypes()['Closure'];
                        $closure_atomic->return_type = $closure_return_type;
                    }
                }
            }
        }

        $unused_params = [];

        if ($context->collect_references
            && !$context->collect_initializations
            && $codebase->find_unused_variables
            && $context->check_variables
        ) {
            foreach ($statements_analyzer->getUnusedVarLocations() as list($var_name, $original_location)) {
                if (!array_key_exists(substr($var_name, 1), $storage->param_types)) {
                    continue;
                }

                if (strpos($var_name, '$_') === 0 || (strpos($var_name, '$unused') === 0 && $var_name !== '$unused')) {
                    continue;
                }

                $position = array_search(substr($var_name, 1), array_keys($storage->param_types), true);

                if ($position === false) {
                    throw new \UnexpectedValueException('$position should not be false here');
                }

                if ($storage->params[$position]->by_ref) {
                    continue;
                }

                if (!($storage instanceof MethodStorage)
                    || $storage->visibility === ClassLikeAnalyzer::VISIBILITY_PRIVATE
                ) {
                    if ($this->function instanceof Closure) {
                        if (IssueBuffer::accepts(
                            new UnusedClosureParam(
                                'Param ' . $var_name . ' is never referenced in this method',
                                $original_location
                            ),
                            $this->getSuppressedIssues()
                        )) {
                            // fall through
                        }
                    } else {
                        if (IssueBuffer::accepts(
                            new UnusedParam(
                                'Param ' . $var_name . ' is never referenced in this method',
                                $original_location
                            ),
                            $this->getSuppressedIssues()
                        )) {
                            // fall through
                        }
                    }
                } else {
                    $fq_class_name = (string)$context->self;

                    $class_storage = $codebase->classlike_storage_provider->get($fq_class_name);

                    $method_name_lc = strtolower($storage->cased_name);

                    if ($storage->abstract || !isset($class_storage->overridden_method_ids[$method_name_lc])) {
                        continue;
                    }

                    $parent_method_id = end($class_storage->overridden_method_ids[$method_name_lc]);

                    if ($parent_method_id) {
                        $parent_method_storage = $codebase->methods->getStorage($parent_method_id);

                        // if the parent method has a param at that position and isn't abstract
                        if (!$parent_method_storage->abstract
                            && isset($parent_method_storage->params[$position])
                        ) {
                            continue;
                        }
                    }

                    $unused_params[$position] = $original_location;
                }
            }

            if ($storage instanceof MethodStorage
                && $class_storage
                && $storage->visibility !== ClassLikeAnalyzer::VISIBILITY_PRIVATE
            ) {
                $method_id_lc = strtolower($this->getMethodId());

                foreach ($storage->params as $i => $_) {
                    if (!isset($unused_params[$i])) {
                        $codebase->file_reference_provider->addMethodParamUse(
                            $method_id_lc,
                            $i,
                            $method_id_lc
                        );

                        /** @var ClassMethod $this->function */
                        $method_name_lc = strtolower($storage->cased_name);

                        if (!isset($class_storage->overridden_method_ids[$method_name_lc])) {
                            continue;
                        }

                        foreach ($class_storage->overridden_method_ids[$method_name_lc] as $parent_method_id) {
                            $codebase->file_reference_provider->addMethodParamUse(
                                strtolower($parent_method_id),
                                $i,
                                $method_id_lc
                            );
                        }
                    }
                }
            }
        }

        foreach ($storage->throws as $expected_exception => $_) {
            if (isset($storage->throw_locations[$expected_exception])) {
                if (ClassLikeAnalyzer::checkFullyQualifiedClassLikeName(
                    $statements_analyzer,
                    $expected_exception,
                    $storage->throw_locations[$expected_exception],
                    $statements_analyzer->getSuppressedIssues(),
                    false,
                    false,
                    true,
                    true
                )) {
                    $input_type = new Type\Union([new TNamedObject($expected_exception)]);
                    $container_type = new Type\Union([new TNamedObject('Exception'), new TNamedObject('Throwable')]);

                    if (!TypeAnalyzer::isContainedBy($codebase, $input_type, $container_type)) {
                        if (IssueBuffer::accepts(
                            new \Psalm\Issue\InvalidThrow(
                                'Class supplied for @throws ' . $expected_exception
                                    . ' does not implement Throwable',
                                $storage->throw_locations[$expected_exception],
                                $expected_exception
                            ),
                            $statements_analyzer->getSuppressedIssues()
                        )) {
                            // fall through
                        }
                    }
                }
            }
        }

        foreach ($statements_analyzer->getUncaughtThrows($context) as $possibly_thrown_exception => $codelocations) {
            $is_expected = false;

            foreach ($storage->throws as $expected_exception => $_) {
                if ($expected_exception === $possibly_thrown_exception
                    || $codebase->classExtends($possibly_thrown_exception, $expected_exception)
                ) {
                    $is_expected = true;
                    break;
                }
            }

            if (!$is_expected) {
                foreach ($codelocations as $codelocation) {
                    // issues are suppressed in ThrowAnalyzer, CallAnalyzer, etc.
                    if (IssueBuffer::accepts(
                        new MissingThrowsDocblock(
                            $possibly_thrown_exception . ' is thrown but not caught - please either catch'
                                . ' or add a @throws annotation',
                            $codelocation
                        )
                    )) {
                        // fall through
                    }
                }
            }
        }

        if ($add_mutations) {
            if ($this->return_vars_in_scope !== null) {
                $context->vars_in_scope = TypeAnalyzer::combineKeyedTypes(
                    $context->vars_in_scope,
                    $this->return_vars_in_scope
                );
            }

            if ($this->return_vars_possibly_in_scope !== null) {
                $context->vars_possibly_in_scope = array_merge(
                    $context->vars_possibly_in_scope,
                    $this->return_vars_possibly_in_scope
                );
            }

            foreach ($context->vars_in_scope as $var => $_) {
                if (strpos($var, '$this->') !== 0 && $var !== '$this') {
                    unset($context->vars_in_scope[$var]);
                }
            }

            foreach ($context->vars_possibly_in_scope as $var => $_) {
                if (strpos($var, '$this->') !== 0 && $var !== '$this') {
                    unset($context->vars_possibly_in_scope[$var]);
                }
            }

            if ($hash && $real_method_id && $this instanceof MethodAnalyzer) {
                $new_hash = md5($real_method_id . '::' . $context->getScopeSummary());

                if ($new_hash === $hash) {
                    self::$no_effects_hashes[$hash] = true;
                }
            }
        }

        return null;
    }

    /**
     * @param Type\Union|null     $return_type
     * @param string              $fq_class_name
     * @param CodeLocation|null   $return_type_location
     *
     * @return  false|null
     */
    public function verifyReturnType(
        StatementsAnalyzer $statements_analyzer,
        Type\Union $return_type = null,
        $fq_class_name = null,
        CodeLocation $return_type_location = null,
        bool $closure_inside_call = false
    ) {
        ReturnTypeAnalyzer::verifyReturnType(
            $this->function,
            $statements_analyzer,
            $this,
            $return_type,
            $fq_class_name,
            $return_type_location,
            [],
            $closure_inside_call
        );
    }

    /**
     * @param string $param_name
     * @param bool $docblock_only
     *
     * @return void
     */
    public function addOrUpdateParamType(
        ProjectAnalyzer $project_analyzer,
        $param_name,
        Type\Union $inferred_return_type,
        $docblock_only = false
    ) {
        $manipulator = FunctionDocblockManipulator::getForFunction(
            $project_analyzer,
            $this->source->getFilePath(),
            $this->getMethodId(),
            $this->function
        );
        $manipulator->setParamType(
            $param_name,
            !$docblock_only && $project_analyzer->getCodebase()->php_major_version >= 7
                ? $inferred_return_type->toPhpString(
                    $this->source->getNamespace(),
                    $this->source->getAliasedClassesFlipped(),
                    $this->source->getFQCLN(),
                    $project_analyzer->getCodebase()->php_major_version,
                    $project_analyzer->getCodebase()->php_minor_version
                ) : null,
            $inferred_return_type->toNamespacedString(
                $this->source->getNamespace(),
                $this->source->getAliasedClassesFlipped(),
                $this->source->getFQCLN(),
                false
            ),
            $inferred_return_type->toNamespacedString(
                $this->source->getNamespace(),
                $this->source->getAliasedClassesFlipped(),
                $this->source->getFQCLN(),
                true
            ),
            $inferred_return_type->canBeFullyExpressedInPhp()
        );
    }

    /**
     * Adds return types for the given function
     *
     * @param   string  $return_type
     * @param   Context $context
     *
     * @return  void
     */
    public function addReturnTypes(Context $context)
    {
        if ($this->return_vars_in_scope !== null) {
            $this->return_vars_in_scope = TypeAnalyzer::combineKeyedTypes(
                $context->vars_in_scope,
                $this->return_vars_in_scope
            );
        } else {
            $this->return_vars_in_scope = $context->vars_in_scope;
        }

        if ($this->return_vars_possibly_in_scope !== null) {
            $this->return_vars_possibly_in_scope = array_merge(
                $context->vars_possibly_in_scope,
                $this->return_vars_possibly_in_scope
            );
        } else {
            $this->return_vars_possibly_in_scope = $context->vars_possibly_in_scope;
        }
    }

    /**
     * @return void
     */
    public function examineParamTypes(
        StatementsAnalyzer $statements_analyzer,
        Context $context,
        Codebase $codebase,
        PhpParser\Node $stmt = null
    ) {
        $storage = $this->getFunctionLikeStorage($statements_analyzer);

        foreach ($storage->params as $i => $param) {
            if ($param->by_ref && isset($context->vars_in_scope['$' . $param->name]) && !$param->is_variadic) {
                $actual_type = $context->vars_in_scope['$' . $param->name];
                $param_out_type = $param->type;

                if (isset($storage->param_out_types[$i])) {
                    $param_out_type = $storage->param_out_types[$i];
                }

                if ($param_out_type && !$actual_type->hasMixed() && $param->location) {
                    if (!TypeAnalyzer::isContainedBy(
                        $codebase,
                        $actual_type,
                        $param_out_type,
                        $actual_type->ignore_nullable_issues,
                        $actual_type->ignore_falsable_issues
                    )
                    ) {
                        if (IssueBuffer::accepts(
                            new ReferenceConstraintViolation(
                                'Variable ' . '$' . $param->name . ' is limited to values of type '
                                    . $param_out_type->getId()
                                    . ' because it is passed by reference, '
                                    . $actual_type->getId() . ' type found. Use @param-out to specify '
                                    . 'a different output type',
                                $stmt
                                    ? new CodeLocation($this, $stmt)
                                    : $param->location
                            ),
                            $statements_analyzer->getSuppressedIssues()
                        )) {
                            // fall through
                        }
                    }
                }
            }
        }
    }

    /**
     * @return null|string
     */
    public function getMethodName()
    {
        if ($this->function instanceof ClassMethod) {
            return (string)$this->function->name;
        }
    }

    /**
     * @param string|null $context_self
     *
     * @return string
     */
    public function getMethodId($context_self = null)
    {
        if ($this->function instanceof ClassMethod) {
            $function_name = (string)$this->function->name;

            return ($context_self ?: $this->source->getFQCLN()) . '::' . strtolower($function_name);
        }

        if ($this->function instanceof Function_) {
            $namespace = $this->source->getNamespace();

            return ($namespace ? strtolower($namespace) . '\\' : '') . strtolower($this->function->name->name);
        }

        return $this->getFilePath()
            . ':' . $this->function->getLine()
            . ':' . (int)$this->function->getAttribute('startFilePos')
            . ':-:closure';
    }

    /**
     * @param string|null $context_self
     *
     * @return string
     */
    public function getCorrectlyCasedMethodId($context_self = null)
    {
        if ($this->function instanceof ClassMethod) {
            $function_name = (string)$this->function->name;

            return ($context_self ?: $this->source->getFQCLN()) . '::' . $function_name;
        }

        if ($this->function instanceof Function_) {
            $namespace = $this->source->getNamespace();

            return ($namespace ? $namespace . '\\' : '') . $this->function->name;
        }

        return $this->getMethodId();
    }

    /**
     * @return FunctionLikeStorage
     */
    public function getFunctionLikeStorage(StatementsAnalyzer $statements_analyzer = null)
    {
        $codebase = $this->codebase;

        if ($this->function instanceof ClassMethod) {
            $method_id = (string) $this->getMethodId();
            $codebase_methods = $codebase->methods;

            try {
                return $codebase_methods->getStorage($method_id);
            } catch (\UnexpectedValueException $e) {
                $declaring_method_id = $codebase_methods->getDeclaringMethodId($method_id);

                if (!$declaring_method_id) {
                    throw new \UnexpectedValueException('Cannot get storage for function that doesn‘t exist');
                }

                // happens for fake constructors
                return $codebase_methods->getStorage($declaring_method_id);
            }
        }

        return $codebase->functions->getStorage($statements_analyzer, (string) $this->getMethodId());
    }

    /**
     * @return array<string, string>
     */
    public function getAliasedClassesFlipped()
    {
        if ($this->source instanceof NamespaceAnalyzer ||
            $this->source instanceof FileAnalyzer ||
            $this->source instanceof ClassLikeAnalyzer
        ) {
            return $this->source->getAliasedClassesFlipped();
        }

        return [];
    }

    /**
     * @return array<string, string>
     */
    public function getAliasedClassesFlippedReplaceable()
    {
        if ($this->source instanceof NamespaceAnalyzer ||
            $this->source instanceof FileAnalyzer ||
            $this->source instanceof ClassLikeAnalyzer
        ) {
            return $this->source->getAliasedClassesFlippedReplaceable();
        }

        return [];
    }

    /**
     * @return string|null
     */
    public function getFQCLN()
    {
        return $this->source->getFQCLN();
    }

    /**
     * @return null|string
     */
    public function getClassName()
    {
        return $this->source->getClassName();
    }

    /**
     * @return array<string, array<string, array{Type\Union}>>|null
     */
    public function getTemplateTypeMap()
    {
        if ($this->source instanceof ClassLikeAnalyzer) {
            return ($this->source->getTemplateTypeMap() ?: [])
                + ($this->storage->template_types ?: []);
        }

        return $this->storage->template_types;
    }

    /**
     * @return string|null
     */
    public function getParentFQCLN()
    {
        return $this->source->getParentFQCLN();
    }

    /**
     * @return bool
     */
    public function isStatic()
    {
        return $this->is_static;
    }

    /**
     * @return StatementsSource
     */
    public function getSource()
    {
        return $this->source;
    }

    public function getCodebase() : Codebase
    {
        return $this->codebase;
    }

    /**
     * Get a list of suppressed issues
     *
     * @return array<string>
     */
    public function getSuppressedIssues()
    {
        return $this->suppressed_issues;
    }

    /**
     * @param array<int, string> $new_issues
     *
     * @return void
     */
    public function addSuppressedIssues(array $new_issues)
    {
        if (isset($new_issues[0])) {
            $new_issues = \array_combine($new_issues, $new_issues);
        }

        $this->suppressed_issues = $new_issues + $this->suppressed_issues;
    }

    /**
     * @param array<int, string> $new_issues
     *
     * @return void
     */
    public function removeSuppressedIssues(array $new_issues)
    {
        if (isset($new_issues[0])) {
            $new_issues = \array_combine($new_issues, $new_issues);
        }

        $this->suppressed_issues = \array_diff_key($this->suppressed_issues, $new_issues);
    }

    /**
     * Adds a suppressed issue, useful when creating a method checker from scratch
     *
     * @param string $issue_name
     *
     * @return void
     */
    public function addSuppressedIssue($issue_name)
    {
        $this->suppressed_issues[] = $issue_name;
    }

    /**
     * @return void
     */
    public static function clearCache()
    {
        self::$no_effects_hashes = [];
    }

    /**
     * @return Type\Union
     */
    public function getLocalReturnType(Type\Union $storage_return_type)
    {
        if ($this->local_return_type) {
            return $this->local_return_type;
        }

        $this->local_return_type = ExpressionAnalyzer::fleshOutType(
            $this->codebase,
            $storage_return_type,
            $this->getFQCLN(),
            $this->getFQCLN(),
            $this->getParentFQCLN()
        );

        return $this->local_return_type;
    }
}