array_flip and array_rand

[mj4444ru]

https://psalm.dev/r/b14406d8ed

How to fix it?

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/b14406d8ed

<?php
$specialChars = array_flip(['~', '!', '@', '#', ':', '$', '%', '^', '&', '*', '?']);
array_rand($specialChars, 2);

Psalm output (using commit 9491ea4):

ERROR: ArgumentTypeCoercion - 3:12 - Argument 1 of array_rand expects non-empty-array<array-key, mixed>, parent type array<"!"|"#"|"$"|"%"|"&"|"*"|":"|"?"|"@"|"^"|"~", 0|1|2|3|4|5|6|7|8|9|10> provided

[orklah]

array_flip transform your array into array<array-key, array-key>, which is correct but not very precise.

For your need, you'd need array<"~"|"!"|"@"|"#"|":"|"$"|"%"|"^"|"&"|"*"|"?", int>. This can be done by adding a return type provider here: https://github.com/vimeo/psalm/tree/master/src/Psalm/Internal/Provider/ReturnTypeProvider

[weirdan]

I think it would be enough to update the stub like this:

diff --git a/stubs/CoreGenericFunctions.phpstub b/stubs/CoreGenericFunctions.phpstub
index e8b3026cf..802f7498d 100644
--- a/stubs/CoreGenericFunctions.phpstub
+++ b/stubs/CoreGenericFunctions.phpstub
@@ -123,7 +123,7 @@ function array_diff_assoc(array $array, array ...$arrays)
  *
  * @param array<TKey, TValue> $array
  *
- * @return array<TValue, TKey>
+ * @return ($array is non-empty-array ? non-empty-array<TValue, TKey> : array<TValue, TKey>)
  * @psalm-pure
  */

[orklah]

Oh, it might indeed