Description
What changes in PHP 8
From the RFC:
PHP distinguishes four kinds of namespaced names:
- Unqualified names like Foo, which coincide with identifiers.
- Qualified names like Foo\Bar.
- Fully qualified names like \Foo.
- Namespace-relative names like namespace\Foo.
Each of these kinds will be represented by a distinct token:
Foo; // Before: T_STRING // After: T_STRING // Rule: {LABEL} Foo\Bar; // Before: T_STRING T_NS_SEPARATOR T_STRING // After: T_NAME_QUALIFIED // Rule: {LABEL}("\\"{LABEL})+ \Foo; // Before: T_NS_SEPARATOR T_STRING // After: T_NAME_FULLY_QUALIFIED // Rule: ("\\"{LABEL})+ namespace\Foo; // Before: T_NAMESPACE T_NS_SEPARATOR T_STRING // After: T_NAME_RELATIVE // Rule: "namespace"("\\"{LABEL})+Individual namespace segments may contain reserved keywords:
// This is interpreted as T_LIST (i.e., as a reserved keyword): List // All of the following are interpreted as legal namespaced names: \List FooBar\List namespace\ListWhitespace (or comments) is not permitted between namespace separators.
Ref: https://wiki.php.net/rfc/namespaced_names_as_token
TL;DR
So, in short, PHP 8.0 introduces 3 new tokens for identifiers, on top of the existing T_STRING:
T_NAME_FULLY_QUALIFIEDT_NAME_RELATIVET_NAME_QUALIFIED
Perspective on this as a sniff author
In the long run, I think these new tokens will make writing sniffs analyzing function calls, class instantiation and the likes much easier, especially when namespace/use statement context needs to be taken into account when matching identifiers.
However, this is also a big breaking change which would require a significant change in how any such sniff is analyzing code.
A significant part of the current test failures against the nightly build for PHPCS itself can be traced back to this particular change. Same for several external standards which I examined.
Proposal for how to handle this change in PHPCS
I'd like to propose the following and would like to invite other sniff authors to give their opinion on this as well:
PHPCS 3.x
For PHPCS 3.x, basically "undo" the change, disregarding any (no longer reserved) keywords.
In practice, this would mean splitting the above tokens on the namespace separator \ and tokenizing the name parts as T_STRING (aside from a potential namespace keyword which would need to be tokenized as T_NAMESPACE).
PHPCS 4.x
For PHPCS 4.x, backfill the PHP 8.0 tokenization for the supported PHP versions < 8.0.
Reasoning
- It moves the breaking change part of this PHP 8.0 change to a major version in PHPCS, which is expected to have breaking changes anyhow.
- It will allow existing sniffs looking for namespace names, use statements, function calls etc to continue to function as before while on PHPCS 3.x.
- It moves the decision on the timing of when to rewrite/adjust these sniffs back to the maintainers of standards as it would coincide with when they will start supporting PHPCS 4.x.
- It moves the decision on whether to concurrently support both types of tokenization to standard maintainers, as it now becomes a decision on whether to concurrently support PHPCS 3.x as well as 4.x in the standard at the same time or to drop support for PHPCS 3.x, or potentially, to have separate branches/versions which work with the different PHPCS versions.
Opinions ?
/cc @gsherwood @photodude @umherirrender @TomasVotruba @sirbrillig @michalbundyra @djoos @louisl @kukulich @carusogabriel @klausi @dereuromark @michalbundyra @jmarcil @weierophinney (and please feel free to ping anyone I missed)