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Suppress function.unusedParameter for params starting with _ #15480
Description
Feature request
Sometimes it's desirable to have free standing functions with one or more unused parameters. This can happen, for example, if you're implementing something like a router that dispatches to a registered function based on some runtime parameter.
function hello_handler(string $method, array $params, array $data): string
{
return "Hello, world!";
}Suppressing the warnings for this function can be done by explicitly referencing them in PHPDocs, but this can be verbose:
/**
* @param string $method
* @param array<string, string> $params
* @param array<string, string> $data
*/
function hello_handler(string $method, array $params, array $data): string
{
return "Hello, world!";
}Other language ecosystems allow this to be avoided in a couple of ways:
- Go treats arguments named
_as dummy arguments. - Rust uses the same rule for unused variables and function params.
- Python's ruff uses _prefix for to inhibit the
unused-function-argumentwarning
Even in PHPStan, the _prefix rule is used in UnusedVariableRule.php for assign.unused and the like.
Adding this for function.unused and co. is very simple.
Did PHPStan help you today? Did it make you happy in any way?
Yes! I'm delighted to see all the new unused warnings in PHPStan 2.3 and they're helping me to clean up a legacy codebase.
Activity
Ignore unused function params prefixed with `_`
claudepache commentedon Oct 15, 2026
You could implement such a rule for your project with a custom Ignore Error Extension.
bpfoley commentedon Oct 15, 2026
Oh nice! Thanks for the suggestion. I'll probably do that for now, but I think this might be a useful feature to have in PHPStan.
bpfoley commentedon Oct 16, 2026
Of course, you can avoid an extension altogether by simply adding the following to your
phpstan.neonstaabm commentedon Oct 17, 2026
needs a phpstan.org/try reproducer
bpfoley commentedon Oct 17, 2026
https://phpstan.org/r/bdfb387b-d23c-4427-965f-4163694792ac
Ignore unused function params prefixed with `_`
Ignore unused function params prefixed with `_`
Ignore unused function params prefixed with `_`
Ignore unused function params prefixed with `_`