Add type checking for hook callbacks in add_action and add_filter…

[szepeviktor]

… (#107)

• Setup the hook callback rule and test.

• Add the wp-hooks library.

• Start adding tests.

• Preparing more tests.

• If we don't have enough arguments, bail out and let PHPStan handle the error.

• If the callback is not valid, bail out and let PHPStan handle the error:

• Simplify this.

• More valid test cases.

• Update some test line numbers.

• First pass at detecting mismatching accepted and expected argument counts.

• Remove some accidental duplicates.

• Fix some logic.

• Let's split this up before it gets out of hand.

• Reduce this down.

• More tidying up.

• We're going to be needing this in multiple methods soon.

• Prep for callback return type checking, not yet functional.

• Split action return type assertion into its own method.

• Bring this message more inline with those used by PHPStan.

• Add detection for filter callbacks with no return value.

• Don't need this just yet.

• Use early exit to reduce code nesting.

• Remove unused imports.

• Yoda comparisons are disallowed.

• Coding standards.

• Remove unused code.

• Use early return to reduce code nesting.

• Remove more unused code.

• Renaming.

• Use early return to reduce code nesting.

• Tidying up.

• Correct logic introduced during refactoring.

• Exclude "maybe" callables.

• More handling for parameter counts.

• More handling for optional parameters in hook callbacks.

• Make the tests more manageable.

• Tests for more callback types.

• Tidying up.

• This isn't used.

• More test cases.

• Tests for variadic callbacks.

• More specific handling for variadic callbacks.

• More tests.

• The hooks names are not relevant to the tests.

• Remove an else.

• I'm still not entirely sure why this works, but it does. Props @herndlm.

• Another test for an action with a return value.

• More variadic handling.

• Turns out PHPStan handles typed and untyped functions differently.

• Partly broken callbacks will trigger an error in PHPStan so we don't need to handle them.

• Terminology.

• Refactoring.

• PHP 7.2 compatibility.

• Reorder the processing so the return type is checked first.

• More tests.

Co-authored-by: Viktor Szépe viktor@szepe.net