False positive InvalidNamedArgument for named arguments to variadic functions

[duskwuff]

Psalm doesn't recognize that variadic functions can be passed arbitrary named arguments:

https://psalm.dev/r/ad5fcd9926

I think this fixes it, but I'm not familiar enough with the codebase to know if it might have unwanted side effects. It might also be worth considering an annotation to indicate whether a variadic parameter should be allowed to handle named parameters.

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArgumentsAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArgumentsAnalyzer.php
index 1ce336501..b0c6811ff 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArgumentsAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArgumentsAnalyzer.php
@@ -665,6 +665,10 @@ class ArgumentsAnalyzer
                         $arg_function_params = [$candidate_param];
                         break;
                     }
+                    if ($candidate_param->is_variadic) {
+                        $arg_function_params = [$candidate_param];
+                        break;
+                    }
                 }
 
                 if (!$arg_function_params) {

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/ad5fcd9926

<?php

function named_variadic(int ...$args) : void {
    var_export($args);
}

named_variadic(named_argument: 1);

Psalm output (using commit 4e8fb9c):

ERROR: InvalidNamedArgument - 7:16 - Parameter $named_argument does not exist on function named_variadic

[muglug]

I think this fixes it, but I'm not familiar enough with the codebase to know if it might have unwanted side effects

If it doesn't break any tests I'm usually happy – PR it!

[duskwuff]

OK, requested. :) Added some basic tests too.