Basic implementation

config.xsd

@@ -89,6 +89,7 @@
         <xs:attribute name="reportInfo" type="xs:boolean" default="true" />
         <xs:attribute name="restrictReturnTypes" type="xs:boolean" default="false" />
         <xs:attribute name="limitMethodComplexity" type="xs:boolean" default="false" />
+        <xs:attribute name="triggerErrorExits" type="TriggerErrorExitsType" default="default" />
     </xs:complexType>
 
     <xs:complexType name="ProjectFilesType">
@@ -646,4 +647,12 @@
             <xs:enumeration value="suppress"/>
         </xs:restriction>
     </xs:simpleType>
+
+    <xs:simpleType name="TriggerErrorExitsType">
+        <xs:restriction base="xs:string">
+            <xs:enumeration value="default"/>
+            <xs:enumeration value="none"/>
+            <xs:enumeration value="always"/>
+        </xs:restriction>
+    </xs:simpleType>
 </xs:schema>

src/Psalm/Config.php

@@ -547,6 +547,11 @@ class Config
     /** @var list<ConfigIssue> */
     public $config_issues = [];
 
+    /**
+     * @var 'default'|'none'|'always'
+     */
+    public $trigger_error_exits = 'default';
+
     protected function __construct()
     {
         self::$instance = $this;
@@ -844,6 +849,7 @@ private static function fromXmlAndPaths(
             'reportInfo' => 'report_info',
             'restrictReturnTypes' => 'restrict_return_types',
             'limitMethodComplexity' => 'limit_method_complexity',
+            'triggerErrorExits' => 'trigger_error_exits',
         ];
 
         foreach ($booleanAttributes as $xmlName => $internalName) {

src/Psalm/Internal/Analyzer/ScopeAnalyzer.php

@@ -102,19 +102,6 @@ public static function getControlActions(
             }
 
             if ($stmt instanceof PhpParser\Node\Stmt\Expression) {
-                if ($stmt->expr instanceof PhpParser\Node\Expr\FuncCall
-                    && $stmt->expr->name instanceof PhpParser\Node\Name
-                    && $stmt->expr->name->parts === ['trigger_error']
-                    && isset($stmt->expr->args[1])
-                    && $stmt->expr->args[1]->value instanceof PhpParser\Node\Expr\ConstFetch
-                    && in_array(
-                        end($stmt->expr->args[1]->value->name->parts),
-                        ['E_ERROR', 'E_PARSE', 'E_CORE_ERROR', 'E_COMPILE_ERROR', 'E_USER_ERROR']
-                    )
-                ) {
-                    return array_values(array_unique(array_merge($control_actions, [self::ACTION_END])));
-                }
-
                 // This allows calls to functions that always exit to act as exit statements themselves
                 if ($nodes
                     && ($stmt_expr_type = $nodes->getType($stmt->expr))

src/Psalm/Internal/Provider/FunctionReturnTypeProvider.php

@@ -71,6 +71,7 @@ public function __construct()
         $this->registerClass(ReturnTypeProvider\FirstArgStringReturnTypeProvider::class);
         $this->registerClass(ReturnTypeProvider\HexdecReturnTypeProvider::class);
         $this->registerClass(ReturnTypeProvider\MinMaxReturnTypeProvider::class);
+        $this->registerClass(ReturnTypeProvider\TriggerErrorReturnTypeProvider::class);
     }
 
     /**

src/Psalm/Internal/Provider/ReturnTypeProvider/TriggerErrorReturnTypeProvider.php

@@ -0,0 +1,64 @@
+<?php declare(strict_types=1);
+
+namespace Psalm\Internal\Provider\ReturnTypeProvider;
+
+use Psalm\Plugin\EventHandler\Event\FunctionReturnTypeProviderEvent;
+use Psalm\Type;
+
+use function in_array;
+
+use const E_USER_DEPRECATED;
+use const E_USER_ERROR;
+use const E_USER_NOTICE;
+use const E_USER_WARNING;
+
+class TriggerErrorReturnTypeProvider implements \Psalm\Plugin\EventHandler\FunctionReturnTypeProviderInterface
+{
+    /**
+     * @return array<lowercase-string>
+     */
+    public static function getFunctionIds(): array
+    {
+        return ['trigger_error'];
+    }
+
+    public static function getFunctionReturnType(FunctionReturnTypeProviderEvent $event): ?Type\Union
+    {
+        $config = $event->getStatementsSource()->getCodebase()->config;
+        if ($config->trigger_error_exits === 'always') {
+            return new Type\Union([new Type\Atomic\TNever()]);
+        }
+
+        if ($config->trigger_error_exits === 'none') {
+            return new Type\Union([new Type\Atomic\TTrue()]);
+        }
+
+        //default behaviour
+        $call_args = $event->getCallArgs();
+        $statements_source = $event->getStatementsSource();
+        if (isset($call_args[1])
+            && ($array_arg_type = $statements_source->getNodeTypeProvider()->getType($call_args[1]->value))
+        ) {
+            $return_types = [];
+            foreach ($array_arg_type->getAtomicTypes() as $atomicType) {
+                if ($atomicType instanceof Type\Atomic\TLiteralInt) {
+                    if (in_array($atomicType->value, [E_USER_WARNING, E_USER_DEPRECATED, E_USER_NOTICE], true)) {
+                        $return_types[] = new Type\Atomic\TTrue();
+                    } elseif ($atomicType->value === E_USER_ERROR) {
+                        $return_types[] = new Type\Atomic\TNever();
+                    } else {
+                        // not recognized int literal. return false before PHP8, fatal error since
+                        $return_types[] = new Type\Atomic\TFalse();
+                    }
+                } else {
+                    $return_types[] = new Type\Atomic\TBool();
+                }
+            }
+
+            return new Type\Union($return_types);
+        }
+
+        //default value is E_USER_NOTICE, so return true
+        return new Type\Union([new Type\Atomic\TTrue()]);
+    }
+}

tests/FunctionCallTest.php

@@ -2126,4 +2126,83 @@ function takesAString(string $s): void{
             ],
         ];
     }
+
+    public function testTriggerErrorDefault(): void
+    {
+        $config = \Psalm\Config::getInstance();
+        $config->trigger_error_exits = 'default';
+
+        $this->addFile(
+            'somefile.php',
+            '<?php
+                /** @return true */
+                function returnsTrue(): bool {
+                    return trigger_error("", E_USER_NOTICE);
+                }
+                /** @return never */
+                function returnsNever(): void {
+                    trigger_error("", E_USER_ERROR);
+                }
+                /**
+                 * @psalm-suppress ArgumentTypeCoercion
+                 * @return mixed
+                 */
+                function returnsNeverOrBool(int $i) {
+                    return trigger_error("", $i);
+                }'
+        );
+
+        //will only pass if no exception is thrown
+        $this->assertTrue(true);
+
+        $this->analyzeFile('somefile.php', new \Psalm\Context());
+    }
+
+    public function testTriggerErrorAlways(): void
+    {
+        $config = \Psalm\Config::getInstance();
+        $config->trigger_error_exits = 'always';
+
+        $this->addFile(
+            'somefile.php',
+            '<?php
+                /** @return never */
+                function returnsNever1(): void {
+                    trigger_error("", E_USER_NOTICE);
+                }
+                /** @return never */
+                function returnsNever2(): void {
+                    trigger_error("", E_USER_ERROR);
+                }'
+        );
+
+        //will only pass if no exception is thrown
+        $this->assertTrue(true);
+
+        $this->analyzeFile('somefile.php', new \Psalm\Context());
+    }
+
+    public function testTriggerErrorNone(): void
+    {
+        $config = \Psalm\Config::getInstance();
+        $config->trigger_error_exits = 'none';
+
+        $this->addFile(
+            'somefile.php',
+            '<?php
+                /** @return true */
+                function returnsTrue1(): bool {
+                    return trigger_error("", E_USER_NOTICE);
+                }
+                /** @return true */
+                function returnsTrue2(): bool {
+                    return trigger_error("", E_USER_ERROR);
+                }'
+        );
+
+        //will only pass if no exception is thrown
+        $this->assertTrue(true);
+
+        $this->analyzeFile('somefile.php', new \Psalm\Context());
+    }
 }