Fix conditional on non empty literal string

Author: VincentLanglet

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

@@ -86,6 +86,11 @@ public static function isContainedBy(
         if ($container_type_part instanceof TNonspecificLiteralString
             && ($input_type_part instanceof TLiteralString || $input_type_part instanceof TNonspecificLiteralString)
         ) {
+            if ($container_type_part instanceof TNonEmptyNonspecificLiteralString) {
+                return ($input_type_part instanceof TLiteralString && $input_type_part->value !== '')
+                    || $input_type_part instanceof TNonEmptyNonspecificLiteralString;
+            }
+
             return true;
         }
 

tests/Template/ConditionalReturnTypeTest.php

@@ -951,6 +951,34 @@ final class SpecificObject extends stdClass {}
                 'ignored_issues' => [],
                 'php_version' => '8.1',
             ],
+            'nonEmptyLiteralString' => [
+                'code' => '<?php
+                    /**
+                     * @param literal-string $string
+                     * @psalm-return ($string is non-empty-literal-string ? string : int)
+                     */
+                    function getSomething(string $string)
+                    {
+                        if (!$string) {
+                            return 1;
+                        }
+
+                        return "";
+                    }
+
+                    /** @var literal-string $literalString */
+                    $literalString;
+                    $something = getSomething($literalString);
+                    /** @var non-empty-literal-string $nonEmptyliteralString */
+                    $nonEmptyliteralString;
+                    $something2 = getSomething($nonEmptyliteralString);
+                ',
+                'assertions' => [
+                    '$something' => 'int|string',
+                    '$something2' => 'string',
+                ],
+                'ignored_issues' => [],
+            ],
         ];
     }
 }