Allow value-of to work with backed enums (fixes #7874).

UPGRADING.md

@@ -64,7 +64,7 @@
    - `Psalm\Type\Atomic\TTraitString`
    - `Psalm\Type\Atomic\TTrue`
    - `Psalm\Type\Atomic\TTypeAlias`
-   - `Psalm\Type\Atomic\TValueOfArray`
+   - `Psalm\Type\Atomic\TValueOf`
    - `Psalm\Type\Atomic\TVoid`
    - `Psalm\Type\Union`
 
@@ -109,7 +109,7 @@
    - `Psalm\Type\Atomic\TTemplateParam`
    - `Psalm\Type\Atomic\TTraitString`
    - `Psalm\Type\Atomic\TTypeAlias`
-   - `Psalm\Type\Atomic\TValueOfArray`
+   - `Psalm\Type\Atomic\TValueOf`
    - `Psalm\Type\Atomic\TVoid`
    - `Psalm\Type\Union`
 - While not a BC break per se, all classes / interfaces / traits / enums under
@@ -156,7 +156,7 @@
 - [BC] To remove a variable from the context, use `Context::remove()`. Calling
   `unset($context->vars_in_scope[$var_id])` can cause problems when using references.
 - [BC] `TKeyOfClassConstant` has been renamed to `TKeyOfArray`.
-- [BC] `TValueOfClassConstant` has been renamed to `TValueOfArray`.
+- [BC] `TValueOfClassConstant` has been renamed to `TValueOf`.
 - [BC] `TKeyOfTemplate` base class has been changed from `Scalar` to `Atomic`.
 - [BC] Class `Psalm\FileManipulation` became final
 - [BC] Class `Psalm\Context` became final
@@ -742,7 +742,7 @@
     - [BC] Class `Psalm\Type\Atomic\TLiteralInt` became final
     - [BC] Class `Psalm\Type\Atomic\TTrue` became final
     - [BC] Class `Psalm\Type\Atomic\TDependentGetClass` became final
-    - [BC] Class `Psalm\Type\Atomic\TValueOfArray` became final
+    - [BC] Class `Psalm\Type\Atomic\TValueOf` became final
     - [BC] Class `Psalm\Type\Atomic\TGenericObject` became final
     - [BC] Class `Psalm\Type\Atomic\TNonEmptyLowercaseString` became final
     - [BC] Class `Psalm\Type\Atomic\TEnumCase` became final

docs/running_psalm/plugins/plugins_type_system.md

@@ -51,13 +51,13 @@ The classes are as follows:
 
 `TKeyOfArray` - Represents an offset of an array (e.g. `key-of<MyClass::CLASS_CONSTANT>`).
 
-`TValueOfArray` - Represents a value of an array (e.g. `value-of<MyClass::CLASS_CONSTANT>`).
+`TValueOf` - Represents a value of an array or enum (e.g. `value-of<MyClass::CLASS_CONSTANT>`).
 
 `TTemplateIndexedAccess` - To be documented
 
 `TTemplateKeyOf` - Represents the type used when using TKeyOfArray when the type of the array is a template
 
-`TTemplateValueOf` - Represents the type used when using TValueOfArray when the type of the array is a template
+`TTemplateValueOf` - Represents the type used when using TValueOf when the type of the array or enum is a template
 
 `TPropertiesOf` - Represents properties and their types of a class as a keyed array (e.g. `properties-of<MyClass>`)
 

src/Psalm/Internal/Type/Comparator/AtomicTypeComparator.php

@@ -36,7 +36,7 @@ use Psalm\Type\Atomic\TString;
 use Psalm\Type\Atomic\TTemplateKeyOf;
 use Psalm\Type\Atomic\TTemplateParam;
 use Psalm\Type\Atomic\TTemplateValueOf;
-use Psalm\Type\Atomic\TValueOfArray;
+use Psalm\Type\Atomic\TValueOf;
 
 use function array_merge;
 use function array_values;
@@ -375,7 +375,7 @@ class AtomicTypeComparator
         }
 
         if ($input_type_part instanceof TTemplateValueOf) {
-            $array_value_type = TValueOfArray::getArrayValueType($input_type_part->as);
+            $array_value_type = TValueOf::getValueType($input_type_part->as, $codebase);
             if ($array_value_type === null) {
                 return false;
             }

src/Psalm/Internal/Type/TemplateInferredTypeReplacer.php

@@ -26,7 +26,7 @@ use Psalm\Type\Atomic\TTemplateParam;
 use Psalm\Type\Atomic\TTemplateParamClass;
 use Psalm\Type\Atomic\TTemplatePropertiesOf;
 use Psalm\Type\Atomic\TTemplateValueOf;
-use Psalm\Type\Atomic\TValueOfArray;
+use Psalm\Type\Atomic\TValueOf;
 use Psalm\Type\Union;
 use UnexpectedValueException;
 
@@ -351,9 +351,9 @@ class TemplateInferredTypeReplacer
         }
 
         if ($atomic_type instanceof TTemplateValueOf
-            && TValueOfArray::isViableTemplateType($template_type)
+            && TValueOf::isViableTemplateType($template_type)
         ) {
-            return new TValueOfArray(clone $template_type);
+            return new TValueOf(clone $template_type);
         }
 
         return null;

src/Psalm/Internal/Type/TypeExpander.php

@@ -34,7 +34,7 @@ use Psalm\Type\Atomic\TObjectWithProperties;
 use Psalm\Type\Atomic\TPropertiesOf;
 use Psalm\Type\Atomic\TTemplateParam;
 use Psalm\Type\Atomic\TTypeAlias;
-use Psalm\Type\Atomic\TValueOfArray;
+use Psalm\Type\Atomic\TValueOf;
 use Psalm\Type\Atomic\TVoid;
 use Psalm\Type\Union;
 use ReflectionProperty;
@@ -364,9 +364,9 @@ class TypeExpander
         }
 
         if ($return_type instanceof TKeyOfArray
-            || $return_type instanceof TValueOfArray
+            || $return_type instanceof TValueOf
         ) {
-            return self::expandKeyOfValueOfArray(
+            return self::expandKeyOfValueOf(
                 $codebase,
                 $return_type,
                 $self_class,
@@ -965,11 +965,11 @@ class TypeExpander
     }
 
     /**
-     * @param TKeyOfArray|TValueOfArray $return_type
+     * @param TKeyOfArray|TValueOf $return_type
      * @param string|TNamedObject|TTemplateParam|null $static_class_type
      * @return non-empty-list<Atomic>
      */
-    private static function expandKeyOfValueOfArray(
+    private static function expandKeyOfValueOf(
         Codebase $codebase,
         Atomic &$return_type,
         ?string $self_class,
@@ -1029,8 +1029,8 @@ class TypeExpander
                     && !TKeyOfArray::isViableTemplateType($constant_type)
                 )
                 || (
-                    $return_type instanceof TValueOfArray
+                    $return_type instanceof TValueOf
-                    && !TValueOfArray::isViableTemplateType($constant_type)
+                    && !TValueOf::isViableTemplateType($constant_type)
                 )
             ) {
                 if ($throw_on_unresolvable_constant) {
@@ -1052,7 +1052,7 @@ class TypeExpander
         if ($return_type instanceof TKeyOfArray) {
             $new_return_types = TKeyOfArray::getArrayKeyType(new Union($type_atomics));
         } else {
-            $new_return_types = TValueOfArray::getArrayValueType(new Union($type_atomics));
+            $new_return_types = TValueOf::getValueType(new Union($type_atomics), $codebase);
         }
         if ($new_return_types === null) {
             return [$return_type];

src/Psalm/Internal/Type/TypeParser.php

@@ -63,7 +63,7 @@ use Psalm\Type\Atomic\TTemplateParamClass;
 use Psalm\Type\Atomic\TTemplatePropertiesOf;
 use Psalm\Type\Atomic\TTemplateValueOf;
 use Psalm\Type\Atomic\TTypeAlias;
-use Psalm\Type\Atomic\TValueOfArray;
+use Psalm\Type\Atomic\TValueOf;
 use Psalm\Type\TypeNode;
 use Psalm\Type\Union;
 
@@ -765,13 +765,13 @@ class TypeParser
                 );
             }
 
-            if (!TValueOfArray::isViableTemplateType($generic_params[0])) {
+            if (!TValueOf::isViableTemplateType($generic_params[0])) {
                 throw new TypeParseTreeException(
                     'Untemplated value-of param ' . $param_name . ' should be an array'
                 );
             }
 
-            return new TValueOfArray($generic_params[0]);
+            return new TValueOf($generic_params[0]);
         }
 
         if ($generic_type_value === 'int-mask') {
@@ -842,7 +842,7 @@ class TypeParser
             $param_type = $param_union_types[0];
 
             if (!$param_type instanceof TClassConstant
-                && !$param_type instanceof TValueOfArray
+                && !$param_type instanceof TValueOf
                 && !$param_type instanceof TKeyOfArray
             ) {
                 throw new TypeParseTreeException(

src/Psalm/Type/Atomic/TIntMaskOf.php

@@ -11,11 +11,11 @@ use Psalm\Type\Atomic;
  */
 final class TIntMaskOf extends TInt
 {
-    /** @var TClassConstant|TKeyOfArray|TValueOfArray */
+    /** @var TClassConstant|TKeyOfArray|TValueOf */
     public $value;
 
     /**
-     * @param TClassConstant|TKeyOfArray|TValueOfArray $value
+     * @param TClassConstant|TKeyOfArray|TValueOf $value
      */
     public function __construct(Atomic $value)
     {

src/Psalm/Type/Atomic/TTemplateValueOf.php

@@ -9,7 +9,7 @@ use Psalm\Type\Atomic;
 use Psalm\Type\Union;
 
 /**
- * Represents the type used when using TValueOfArray when the type of the array is a template
+ * Represents the type used when using TValueOf when the type of the array or enum is a template
  */
 final class TTemplateValueOf extends Atomic
 {

src/Psalm/Type/Atomic/TValueOf.php

@@ -2,16 +2,21 @@
 
 namespace Psalm\Type\Atomic;
 
+use Psalm\Codebase;
+use Psalm\Internal\Codebase\ConstantTypeResolver;
+use Psalm\Storage\EnumCaseStorage;
 use Psalm\Type\Atomic;
 use Psalm\Type\Union;
 
-use function array_merge;
+use function array_map;
 use function array_values;
+use function assert;
+use function count;
 
 /**
- * Represents a value of an array.
+ * Represents a value of an array or enum.
  */
-final class TValueOfArray extends Atomic
+final class TValueOf extends Atomic
 {
     /** @var Union */
     public $type;
@@ -56,6 +61,7 @@ final class TValueOfArray extends Atomic
                 && !$type instanceof TKeyedArray
                 && !$type instanceof TList
                 && !$type instanceof TPropertiesOf
+                && !$type instanceof TNamedObject
             ) {
                 return false;
             }
@@ -63,39 +69,58 @@ final class TValueOfArray extends Atomic
         return true;
     }
 
-    public static function getArrayValueType(
+    public static function getValueType(
         Union $type,
-        bool $keep_template_params = false
+        Codebase $codebase,
+        bool $keep_template_params = false,
     ): ?Union {
         $value_types = [];
 
         foreach ($type->getAtomicTypes() as $atomic_type) {
             if ($atomic_type instanceof TArray) {
-                $array_value_atomics = $atomic_type->type_params[1];
+                $value_atomics = $atomic_type->type_params[1];
             } elseif ($atomic_type instanceof TList) {
-                $array_value_atomics = $atomic_type->type_param;
+                $value_atomics = $atomic_type->type_param;
             } elseif ($atomic_type instanceof TKeyedArray) {
-                $array_value_atomics = $atomic_type->getGenericValueType();
+                $value_atomics = $atomic_type->getGenericValueType();
             } elseif ($atomic_type instanceof TTemplateParam) {
                 if ($keep_template_params) {
-                    $array_value_atomics = new Union([$atomic_type]);
+                    $value_atomics = new Union([$atomic_type]);
                 } else {
-                    $array_value_atomics = static::getArrayValueType(
+                    $value_atomics = static::getValueType(
                         $atomic_type->as,
+                        $codebase,
                         $keep_template_params
                     );
-                    if ($array_value_atomics === null) {
+                    if ($value_atomics === null) {
                         continue;
                     }
                 }
+            } elseif ($atomic_type instanceof TNamedObject
+                && $codebase->classlike_storage_provider->has($atomic_type->value)
+            ) {
+                $class_storage = $codebase->classlike_storage_provider->get($atomic_type->value);
+                $cases = $class_storage->enum_cases;
+                if (!$class_storage->is_enum
+                    || $class_storage->enum_type === null
+                    || count($cases) === 0
+                ) {
+                    // Invalid value-of, skip
+                    continue;
+                }
+
+                $value_atomics = new Union(array_map(
+                    function (EnumCaseStorage $case): Atomic {
+                        assert($case->value !== null); // Backed enum must have a value
+                        return ConstantTypeResolver::getLiteralTypeFromScalarValue($case->value);
+                    },
+                    array_values($cases),
+                ));
             } else {
                 continue;
             }
 
-            $value_types = array_merge(
+            $value_types = [...$value_types, ...array_values($value_atomics->getAtomicTypes())];
-                $value_types,
-                array_values($array_value_atomics->getAtomicTypes())
-            );
         }
 
         if ($value_types === []) {

tests/ValueOfTest.php

@@ -7,7 +7,7 @@ namespace Psalm\Tests;
 use Psalm\Tests\Traits\InvalidCodeAnalysisTestTrait;
 use Psalm\Tests\Traits\ValidCodeAnalysisTestTrait;
 
-class ValueOfArrayTest extends TestCase
+class ValueOfTest extends TestCase
 {
     use InvalidCodeAnalysisTestTrait;
     use ValidCodeAnalysisTestTrait;
@@ -141,6 +141,74 @@ class ValueOfArrayTest extends TestCase
                     }
                 ',
             ],
+            'valueOfStringEnum' => [
+                'code' => '<?php
+                    enum Foo: string
+                    {
+                        case Foo = "foo";
+                        case Bar = "bar";
+                    }
+
+                    /** @param value-of<Foo> $arg */
+                    function foobar(string $arg): void
+                    {
+                        /** @psalm-check-type-exact $arg = "foo"|"bar" */;
+                    }
+
+                    /** @var Foo */
+                    $foo = Foo::Foo;
+                    foobar($foo->value);
+                ',
+                'assertions' => [],
+                'ignored_issues' => [],
+                'php_version' => '8.1',
+            ],
+            'valueOfIntEnum' => [
+                'code' => '<?php
+                    enum Foo: int
+                    {
+                        case Foo = 2;
+                        case Bar = 3;
+                    }
+
+                    /** @param value-of<Foo> $arg */
+                    function foobar(int $arg): void
+                    {
+                        /** @psalm-check-type-exact $arg = 2|3 */;
+                    }
+
+                    /** @var Foo */
+                    $foo = Foo::Foo;
+                    foobar($foo->value);
+                ',
+                'assertions' => [],
+                'ignored_issues' => [],
+                'php_version' => '8.1',
+            ],
+            'valueOfEnumUnion' => [
+                'code' => '<?php
+                    enum Foo: int
+                    {
+                        case Foo = 2;
+                        case Bar = 3;
+                    }
+
+                    enum Bar: string
+                    {
+                        case Foo = "foo";
+                        case Bar = "bar";
+                    }
+
+                    /** @param value-of<Foo|Bar> $arg */
+                    function foobar(int|string $arg): void
+                    {
+                        /** @psalm-check-type-exact $arg = 2|3|"foo"|"bar" */;
+                    }
+                ',
+                'assertions' => [],
+                'ignored_issues' => [],
+                'php_version' => '8.1',
+            ],
         ];
     }
 
@@ -212,6 +280,23 @@ class ValueOfArrayTest extends TestCase
                 ',
                 'error_message' => 'InvalidReturnStatement'
             ],
+            'valueOfUnitEnum' => [
+                'code' => '<?php
+                    enum Foo
+                    {
+                        case Foo;
+                        case Bar;
+                    }
+
+                    /** @param value-of<Foo> $arg */
+                    function foobar(string $arg): void {}
+                ',
+                // TODO turn this into an InvalidDocblock with a better error message. This is difficult because it
+                // has to happen after scanning has finished, otherwise the class might not have been scanned yet.
+                'error_message' => 'MismatchingDocblockParamType',
+                'ignored_issues' => [],
+                'php_version' => '8.1',
+            ],
         ];
     }
 }