Support intersections with __toString

Fixes #3149
vimeo · Apr 27, 2020 · e65bffc · e65bffc
1 parent 5331a3e
commit e65bffc
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Showing 2 changed files with 62 additions and 27 deletions.
diff --git a/src/Psalm/Internal/Analyzer/Statements/ExpressionAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/ExpressionAnalyzer.php
@@ -2229,39 +2229,51 @@ private static function castStringAttempt(
             }
 
             if ($atomic_type instanceof TNamedObject
-                && $codebase->methods->methodExists(
-                    new \Psalm\Internal\MethodIdentifier(
-                        $atomic_type->value,
-                        '__tostring'
-                    )
-                )
+                || $atomic_type instanceof TObject
             ) {
-                $return_type = $codebase->methods->getMethodReturnType(
-                    new \Psalm\Internal\MethodIdentifier(
-                        $atomic_type->value,
-                        '__tostring'
-                    ),
-                    $self_class
-                );
+                $intersection_types = [$atomic_type];
 
-                if ($return_type) {
-                    $castable_types = array_merge(
-                        $castable_types,
-                        array_values($return_type->getAtomicTypes())
-                    );
-                } else {
-                    $castable_types[] = new TString();
+                if ($atomic_type->extra_types) {
+                    $intersection_types = array_merge($intersection_types, $atomic_type->extra_types);
                 }
 
-                continue;
-            }
+                foreach ($intersection_types as $intersection_type) {
+                    if ($intersection_type instanceof TNamedObject
+                        && $codebase->methods->methodExists(
+                            new \Psalm\Internal\MethodIdentifier(
+                                $intersection_type->value,
+                                '__tostring'
+                            )
+                        )
+                    ) {
+                        $return_type = $codebase->methods->getMethodReturnType(
+                            new \Psalm\Internal\MethodIdentifier(
+                                $intersection_type->value,
+                                '__tostring'
+                            ),
+                            $self_class
+                        );
 
-            if ($atomic_type instanceof Type\Atomic\TObjectWithProperties
-                && isset($atomic_type->methods['__toString'])
-            ) {
-                $castable_types[] = new TString();
+                        if ($return_type) {
+                            $castable_types = array_merge(
+                                $castable_types,
+                                array_values($return_type->getAtomicTypes())
+                            );
+                        } else {
+                            $castable_types[] = new TString();
+                        }
 
-                continue;
+                        continue 2;
+                    }
+
+                    if ($intersection_type instanceof Type\Atomic\TObjectWithProperties
+                        && isset($intersection_type->methods['__toString'])
+                    ) {
+                        $castable_types[] = new TString();
+
+                        continue 2;
+                    }
+                }
             }
 
             if ($atomic_type instanceof Type\Atomic\TTemplateParam) {

diff --git a/tests/ToStringTest.php b/tests/ToStringTest.php
@@ -119,6 +119,29 @@ function __toString(): string {
                         }
                     }'
             ],
+            'intersectionCanBeString' => [
+                '<?php
+                    interface EmptyInterface {}
+
+                    class StringCastable implements EmptyInterface
+                    {
+                        public function __toString()
+                        {
+                            return \'I am castable\';
+                        }
+                    }
+
+                    function factory(): EmptyInterface
+                    {
+                        return new StringCastable();
+                    }
+
+                    $object = factory();
+                    if (method_exists($object, \'__toString\')) {
+                        $a = (string) $object;
+                        echo $a;
+                    }'
+            ],
         ];
     }