Allow updating of params

src/Psalm/Checker/CommentChecker.php

@@ -380,7 +380,7 @@ class CommentChecker
      *
      * @return array<string>
      */
-    protected static function splitDocLine($return_block)
+    public static function splitDocLine($return_block)
     {
         $brackets = '';
 

src/Psalm/Checker/FunctionLikeChecker.php

@@ -305,6 +305,14 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                     $signature_type
                 )
                 ) {
+                    if ($project_checker->alter_code
+                        && isset($project_checker->getIssuesToFix()['MismatchingDocblockParamType'])
+                    ) {
+                        $this->addOrUpdateParamType($project_checker, $function_param->name, $signature_type, true);
+
+                        return null;
+                    }
+
                     if (IssueBuffer::accepts(
                         new MismatchingDocblockParamType(
                             'Parameter $' . $function_param->name . ' has wrong type \'' . $param_type .
@@ -1423,6 +1431,47 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
         return null;
     }
 
+    /**
+     * @param string $param_name
+     * @param bool $docblock_only
+     *
+     * @return void
+     */
+    private function addOrUpdateParamType(
+        ProjectChecker $project_checker,
+        $param_name,
+        Type\Union $inferred_return_type,
+        $docblock_only = false
+    ) {
+        $manipulator = FunctionDocblockManipulator::getForFunction(
+            $project_checker,
+            $this->source->getFilePath(),
+            $this->getMethodId(),
+            $this->function
+        );
+        $manipulator->setParamType(
+            $param_name,
+            !$docblock_only && $project_checker->php_major_version >= 7
+                ? $inferred_return_type->toPhpString(
+                    $this->source->getAliasedClassesFlipped(),
+                    $this->source->getFQCLN(),
+                    $project_checker->php_major_version,
+                    $project_checker->php_minor_version
+                ) : null,
+            $inferred_return_type->toNamespacedString(
+                $this->source->getAliasedClassesFlipped(),
+                $this->source->getFQCLN(),
+                false
+            ),
+            $inferred_return_type->toNamespacedString(
+                $this->source->getAliasedClassesFlipped(),
+                $this->source->getFQCLN(),
+                true
+            ),
+            $inferred_return_type->canBeFullyExpressedInPhp()
+        );
+    }
+
     /**
      * @param bool $docblock_only
      *

src/Psalm/FileManipulation/FunctionDocblockManipulator.php

@@ -50,6 +50,27 @@ class FunctionDocblockManipulator
     /** @var ?string */
     private $new_psalm_return_type;
 
+    /** @var array<string, int> */
+    private $param_typehint_area_starts = [];
+
+    /** @var array<string, int> */
+    private $param_typehint_starts = [];
+
+    /** @var array<string, int> */
+    private $param_typehint_ends = [];
+
+    /** @var array<string, string> */
+    private $new_php_param_types = [];
+
+    /** @var array<string, bool> */
+    private $param_type_is_php_compatible = [];
+
+    /** @var array<string, string> */
+    private $new_phpdoc_param_types = [];
+
+    /** @var array<string, string> */
+    private $new_psalm_param_types = [];
+
     /** @var string */
     private $indentation;
 
@@ -92,6 +113,8 @@ class FunctionDocblockManipulator
 
         $file_contents = $project_checker->getFileContents($file_path);
 
+
+
         $last_arg_position = $stmt->params
             ? (int) $stmt->params[count($stmt->params) - 1]->getAttribute('endFilePos')
             : null;
@@ -158,7 +181,7 @@ class FunctionDocblockManipulator
     }
 
     /**
-     * Sets the new docblock return type
+     * Sets the new return type
      *
      * @param   ?string     $php_type
      * @param   string      $new_type
@@ -177,6 +200,30 @@ class FunctionDocblockManipulator
         $this->return_type_is_php_compatible = $is_php_compatible;
     }
 
+    /**
+     * Sets a new param type
+     *
+     * @param   string      $param_name
+     * @param   ?string     $php_type
+     * @param   string      $new_type
+     * @param   string      $phpdoc_type
+     * @param   bool        $is_php_compatible
+     *
+     * @return  void
+     */
+    public function setParamType($param_name, $php_type, $new_type, $phpdoc_type, $is_php_compatible)
+    {
+
+        $new_type = str_replace(['<mixed, mixed>', '<empty, empty>'], '', $new_type);
+
+        if ($php_type) {
+            $this->new_php_param_types[$param_name] = $php_type;
+        }
+        $this->new_phpdoc_param_types[$param_name] = $phpdoc_type;
+        $this->new_psalm_param_types[$param_name] = $new_type;
+        $this->param_type_is_php_compatible[$param_name] = $is_php_compatible;
+    }
+
     /**
      * Gets a new docblock given the existing docblock, if one exists, and the updated return types
      * and/or parameters
@@ -193,6 +240,27 @@ class FunctionDocblockManipulator
             $parsed_docblock = ['description' => ''];
         }
 
+        foreach ($this->new_phpdoc_param_types as $param_name => $phpdoc_type) {
+            $found_in_params = false;
+            $new_param_block = $phpdoc_type . ' ' . '$' . $param_name;
+
+            if (isset($parsed_docblock['specials']['param'])) {
+                foreach ($parsed_docblock['specials']['param'] as &$param_block) {
+                    $doc_parts = CommentChecker::splitDocLine($param_block);
+
+                    if ($doc_parts[1] === '$' . $param_name) {
+                        $param_block = $new_param_block;
+                        $found_in_params = true;
+                        break;
+                    }
+                }
+            }
+
+            if (!$found_in_params) {
+                $parsed_docblock['specials']['params'][] = $new_param_block;
+            }
+        }
+
         if ($this->new_phpdoc_return_type) {
             $parsed_docblock['specials']['return'] = [$this->new_phpdoc_return_type];
         }

tests/FileManipulationTest.php

@@ -257,6 +257,42 @@ class FileManipulationTest extends TestCase
                 '7.0',
                 ['InvalidReturnType'],
             ],
+            'fixMismatchingDocblockReturnType70' => [
+                '<?php
+                    /**
+                     * @return int
+                     */
+                    function foo() : string {
+                        return "hello";
+                    }',
+                '<?php
+                    /**
+                     * @return string
+                     */
+                    function foo() : string {
+                        return "hello";
+                    }',
+                '7.0',
+                ['MismatchingDocblockReturnType'],
+            ],
+            'fixMismatchingDocblockParamType70' => [
+                '<?php
+                    /**
+                     * @param int $s
+                     */
+                    function foo(string $s) : string {
+                        return "hello";
+                    }',
+                '<?php
+                    /**
+                     * @param string $s
+                     */
+                    function foo(string $s) : string {
+                        return "hello";
+                    }',
+                '7.0',
+                ['MismatchingDocblockParamType'],
+            ],
             'useUnqualifierPlugin' => [
                 '<?php
                     namespace A\B\C {