Correctly identify referenced enum values in enum cases

src/Psalm/Internal/PhpVisitor/Reflector/ClassLikeNodeScanner.php

@@ -1453,6 +1453,10 @@ private function visitEnumDeclaration(
                 $fq_classlike_name,
             );
 
+            if ($case_type && $case_type->isSingleEnumCase()) {
+                $case_type = Type\Atomic\TValueOf::getValueType($case_type, $this->codebase);
+            }
+
             if ($case_type) {
                 if ($case_type->isSingleIntLiteral()) {
                     $enum_value = $case_type->getSingleIntLiteral()->value;

src/Psalm/Type/MutableUnion.php

@@ -9,6 +9,7 @@
 use Psalm\Type\Atomic\Scalar;
 use Psalm\Type\Atomic\TArray;
 use Psalm\Type\Atomic\TClassString;
+use Psalm\Type\Atomic\TEnumCase;
 use Psalm\Type\Atomic\TFalse;
 use Psalm\Type\Atomic\TFloat;
 use Psalm\Type\Atomic\TInt;
@@ -174,6 +175,11 @@ final class MutableUnion implements TypeNode
      */
     private array $literal_float_types = [];
 
+    /**
+     * @var array<string, TEnumCase>
+     */
+    private array $enum_case_types = [];
+
     /**
      * True if the type was passed or returned by reference, or if the type refers to an object's
      * property or an item in an array. Note that this is not true for locally created references

src/Psalm/Type/Union.php

@@ -6,6 +6,7 @@
 use Psalm\Internal\TypeVisitor\FromDocblockSetter;
 use Psalm\Storage\ImmutableNonCloneableTrait;
 use Psalm\Type\Atomic\TClassString;
+use Psalm\Type\Atomic\TEnumCase;
 use Psalm\Type\Atomic\TLiteralFloat;
 use Psalm\Type\Atomic\TLiteralInt;
 use Psalm\Type\Atomic\TLiteralString;
@@ -186,6 +187,11 @@ final class Union implements TypeNode
      */
     private array $literal_float_types = [];
 
+    /**
+     * @var array<string, TEnumCase>
+     */
+    private array $enum_case_types = [];
+
     /**
      * True if the type was passed or returned by reference, or if the type refers to an object's
      * property or an item in an array. Note that this is not true for locally created references

src/Psalm/Type/UnionTrait.php

@@ -21,6 +21,7 @@
 use Psalm\Type\Atomic\TClosure;
 use Psalm\Type\Atomic\TConditional;
 use Psalm\Type\Atomic\TEmptyMixed;
+use Psalm\Type\Atomic\TEnumCase;
 use Psalm\Type\Atomic\TFalse;
 use Psalm\Type\Atomic\TInt;
 use Psalm\Type\Atomic\TIntRange;
@@ -97,6 +98,8 @@ public function __construct(array $types, array $properties = [])
                 && ($type->as_type || $type instanceof TTemplateParamClass)
             ) {
                 $this->typed_class_strings[$key] = $type;
+            } elseif ($type instanceof TEnumCase) {
+                $this->enum_case_types[$key] = $type;
             } elseif ($type instanceof TNever) {
                 $this->explicit_never = true;
             }
@@ -1558,4 +1561,9 @@ public function visit(TypeVisitor $visitor): bool
 
         return true;
     }
+
+    public function isSingleEnumCase(): bool
+    {
+        return count($this->types) === 1 && count($this->enum_case_types) === 1;
+    }
 }