Implement Shorter Attribute Syntax

[theodorejb]

RFC: https://wiki.php.net/rfc/shorter_attribute_syntax.

Implements the @@ syntax for attributes. @kooldev did the initial implementation, and I added support for trailing commas in the attribute argument list.

// before
<<Attribute>>
class Foo {}

// after
@@Attribute
class Foo {}

[nikic]

I've landed the trailing comma part of this in a more general way (that will be compatible with things like named args in the future) in 6a195ca.

[beberlei]

@theodorejb you can use the Github co-author feature to mention Martin in the commit message with Co-authored-by: Martin Schröder <m.schroeder2007@gmail.com>

[beberlei]

@SerafimArts this is not the place to discuss the selected syntax, please see the mailing list discussion on this RFC.

please also be mindful that this has been picked by democratic vote and that this vote is now completed, at some point decisions have to be made and are final, this is the PHP contribution and governance model.

[nikic]

I have landed #5827 now. Can you please rebase on top of it?

[theodorejb]

@nikic I rebased it now. For some reason test 19 "Attribute name cannot be a variable" is failing for me, though. Is there something I'm missing in the parser?

[nikic]

What's the new output you get there? It's normal for parse error messages to change in small ways.

[kooldev]

I want to point out that after recent changes to the lexer in this PR it permits whitespace and comments between @@ and the attribute name. This was not allowed in my original @: / @@ implementation. For example the following code works with the current implementation:

function foo(@@A1@@ /* foo */ A1 \stdClass $p) { }

There is no need for any whitespace / non-name-char before @@. While this is not a technical problem it is pretty bad code style. All kinds of whitespace and comments are now allowed to sit between the token and the name and parse just fine. The following code can be parsed and works (as far as the parser is concerned) but is very difficult to read (and again bad code style):

@@ A1
@@

// Some comment
A1 class Test { }

The use of whitespace / comments is also possible with <<>> or #[] syntax, but having an ending delimiter improves readability in these cases. The other syntax(es) also support writing multiple attributes without any whitespace in between. Again the endling delimiter helps a little bit with readability (and grouping should have been used to avoid multiple enclosings anyways).

function foo(<<A1>><< A1>> \stdClass $p) { }
function foo(#[A1]#[ A1] \stdClass $p) { }

I am not sure if you consider this to be a problem but maybe you should adjust the lexer to enforce @@ to be immediately followed by a character that may start a name?

[nikic]

@kooldev Not a problem from our perspective, as we leave the enforcement of coding style to other projects. This is no different from someone deciding to write

Foo
// haha
::
// haha
Bar
// haha
;

or some equally silly, but still valid, code.

[nikic]

The patch looks good to me, but we should probably wait for the outcome of https://externals.io/message/111101 before merging this.

[theodorejb]

@nikic I assume this can be merged now per Sara's comment? https://externals.io/message/111101#111158

[beberlei]

I'll merge the PR next week.