[FEATURE] Allow to intercept adding issue in IssueBuffer

docs/running_psalm/plugins/authoring_plugins.md

@@ -81,6 +81,7 @@ class SomePlugin implements \Psalm\Plugin\EventHandler\AfterStatementAnalysisInt
 - `AfterFunctionLikeAnalysisInterface` - called after Psalm has completed its analysis of a given function-like.
 - `AfterMethodCallAnalysisInterface` - called after Psalm analyzes a method call.
 - `AfterStatementAnalysisInterface` - called after Psalm evaluates an statement.
+- `BeforeAddIssueInterface` - called before Psalm adds an item to it's internal `IssueBuffer`, allows handling code issues individually
 - `BeforeFileAnalysisInterface` - called before Psalm analyzes a file.
 - `FunctionExistenceProviderInterface` - can be used to override Psalm's builtin function existence checks for one or more functions.
 - `FunctionParamsProviderInterface.php` - can be used to override Psalm's builtin function parameter lookup for one or more functions.

src/Psalm/Internal/EventDispatcher.php

@@ -15,6 +15,7 @@
 use Psalm\Plugin\EventHandler\AfterFunctionLikeAnalysisInterface;
 use Psalm\Plugin\EventHandler\AfterMethodCallAnalysisInterface;
 use Psalm\Plugin\EventHandler\AfterStatementAnalysisInterface;
+use Psalm\Plugin\EventHandler\BeforeAddIssueInterface;
 use Psalm\Plugin\EventHandler\BeforeFileAnalysisInterface;
 use Psalm\Plugin\EventHandler\Event\AddRemoveTaintsEvent;
 use Psalm\Plugin\EventHandler\Event\AfterAnalysisEvent;
@@ -29,6 +30,7 @@
 use Psalm\Plugin\EventHandler\Event\AfterFunctionLikeAnalysisEvent;
 use Psalm\Plugin\EventHandler\Event\AfterMethodCallAnalysisEvent;
 use Psalm\Plugin\EventHandler\Event\AfterStatementAnalysisEvent;
+use Psalm\Plugin\EventHandler\Event\BeforeAddIssueEvent;
 use Psalm\Plugin\EventHandler\Event\BeforeFileAnalysisEvent;
 use Psalm\Plugin\EventHandler\Event\StringInterpreterEvent;
 use Psalm\Plugin\EventHandler\RemoveTaintsInterface;
@@ -37,6 +39,7 @@
 
 use function array_merge;
 use function count;
+use function is_bool;
 use function is_subclass_of;
 
 /**
@@ -122,6 +125,11 @@ class EventDispatcher
      */
     public $after_codebase_populated = [];
 
+    /**
+     * @var list<class-string<BeforeAddIssueInterface>>
+     */
+    private array $before_add_issue = [];
+
     /**
      * Static methods to be called after codebase has been populated
      *
@@ -209,6 +217,10 @@ public function registerClass(string $class): void
             $this->after_codebase_populated[] = $class;
         }
 
+        if (is_subclass_of($class, BeforeAddIssueInterface::class)) {
+            $this->before_add_issue[] = $class;
+        }
+
         if (is_subclass_of($class, AfterAnalysisInterface::class)) {
             $this->after_analysis[] = $class;
         }
@@ -330,6 +342,17 @@ public function dispatchAfterCodebasePopulated(AfterCodebasePopulatedEvent $even
         }
     }
 
+    public function dispatchBeforeAddIssue(BeforeAddIssueEvent $event): ?bool
+    {
+        foreach ($this->before_add_issue as $handler) {
+            $result = $handler::beforeAddIssue($event);
+            if (is_bool($result)) {
+                return $result;
+            }
+        }
+        return null;
+    }
+
     public function dispatchAfterAnalysis(AfterAnalysisEvent $event): void
     {
         foreach ($this->after_analysis as $handler) {

src/Psalm/IssueBuffer.php

@@ -16,6 +16,7 @@
 use Psalm\Issue\TaintedInput;
 use Psalm\Issue\UnusedPsalmSuppress;
 use Psalm\Plugin\EventHandler\Event\AfterAnalysisEvent;
+use Psalm\Plugin\EventHandler\Event\BeforeAddIssueEvent;
 use Psalm\Report\CheckstyleReport;
 use Psalm\Report\CodeClimateReport;
 use Psalm\Report\CompactReport;
@@ -250,6 +251,11 @@ public static function add(CodeIssue $e, bool $is_fixable = false): bool
     {
         $config = Config::getInstance();
 
+        $event = new BeforeAddIssueEvent($e, $is_fixable);
+        if ($config->eventDispatcher->dispatchBeforeAddIssue($event) === false) {
+            return false;
+        };
+
         $fqcn_parts = explode('\\', get_class($e));
         $issue_type = array_pop($fqcn_parts);
 

src/Psalm/Plugin/EventHandler/BeforeAddIssueInterface.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psalm\Plugin\EventHandler;
+
+use Psalm\Plugin\EventHandler\Event\BeforeAddIssueEvent;
+
+interface BeforeAddIssueInterface
+{
+    /**
+     * Called before adding a code issue.
+     *
+     * Note that event handlers are called in the order they were registered, and thus
+     * the handler registered earlier may prevent subsequent handlers from running by
+     * returning a boolean value.
+     *
+     * @param BeforeAddIssueEvent $event
+     * @return null|bool $event How and whether to continue:
+     *  + `null` continues with next event handler
+     *  + `true` stops event handling & keeps issue
+     *  + `false` stops event handling & ignores issue
+     */
+    public static function beforeAddIssue(BeforeAddIssueEvent $event): ?bool;
+}

src/Psalm/Plugin/EventHandler/Event/BeforeAddIssueEvent.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psalm\Plugin\EventHandler\Event;
+
+use Psalm\Issue\CodeIssue;
+
+final class BeforeAddIssueEvent
+{
+    /**
+     * @var CodeIssue
+     */
+    private CodeIssue $issue;
+
+    /**
+     * @var bool
+     */
+    private bool $fixable;
+
+    /** @internal */
+    public function __construct(CodeIssue $issue, bool $fixable)
+    {
+        $this->issue = $issue;
+        $this->fixable = $fixable;
+    }
+
+    public function getIssue(): CodeIssue
+    {
+        return $this->issue;
+    }
+
+    public function isFixable(): bool
+    {
+        return $this->fixable;
+    }
+}

tests/CodebaseTest.php

@@ -7,8 +7,13 @@
 use Psalm\Codebase;
 use Psalm\Context;
 use Psalm\Exception\UnpopulatedClasslikeException;
+use Psalm\Issue\InvalidReturnStatement;
+use Psalm\Issue\InvalidReturnType;
+use Psalm\IssueBuffer;
 use Psalm\Plugin\EventHandler\AfterClassLikeVisitInterface;
+use Psalm\Plugin\EventHandler\BeforeAddIssueInterface;
 use Psalm\Plugin\EventHandler\Event\AfterClassLikeVisitEvent;
+use Psalm\Plugin\EventHandler\Event\BeforeAddIssueEvent;
 use Psalm\PluginRegistrationSocket;
 use Psalm\Tests\Internal\Provider\ClassLikeStorageInstanceCacheProvider;
 use Psalm\Type;
@@ -207,4 +212,45 @@ public function classExtendsRejectsUnpopulatedClasslikes(): void
 
         $this->codebase->classExtends('A', 'B');
     }
+
+    /**
+     * @test
+     */
+    public function addingCodeIssueIsIntercepted(): void
+    {
+        $this->addFile(
+            'somefile.php',
+            '<?php
+                namespace Psalm\CurrentTest;
+                function invalidReturnType(int $value): string
+                {
+                    return $value;
+                }
+                echo invalidReturnType(123);
+            '
+        );
+
+        $eventHandler = new class implements BeforeAddIssueInterface
+        {
+            public static function beforeAddIssue(BeforeAddIssueEvent $event): ?bool
+            {
+                $issue = $event->getIssue();
+                if ($issue->code_location->file_path !== 'somefile.php') {
+                    return null;
+                }
+                if ($issue instanceof InvalidReturnStatement && $event->isFixable() === false) {
+                    return false;
+                } elseif ($issue instanceof InvalidReturnType && $event->isFixable() === true) {
+                    return false;
+                }
+                return null;
+            }
+        };
+
+        (new PluginRegistrationSocket($this->codebase->config, $this->codebase))
+            ->registerHooksFromClass(get_class($eventHandler));
+
+        $this->analyzeFile('somefile.php', new Context);
+        self::assertSame(0, IssueBuffer::getErrorCount());
+    }
 }