[PHP 8.0] Add attributes v2 support

[TomasVotruba]

Closes #659

Note, this comes handy (found out 1 hour too later than needed 🤦 ):

php test/updateTests.php

[TomasVotruba]

@nikic It's goes pretty well so far. I just got stuck on simple test case: 8025300#diff-39ff209fb56c0dd7ab3dcde01b4c6df1

<?php

<<Deprecated>>
function a() {
}

With:

1) PhpParser\CodeParsingTest::testParse with data set "var/www/PHP-Parser/test/code/parser/stmt/function/attributes.test#0" ('Attributes (/var/www/PHP-Pars....test)', '<?php\n\n<<Deprecated>>\nfunc...) {\n}', 'array(\n    0: Stmt_Function(...  )\n)', null)
Attributes (/var/www/PHP-Parser/test/code/parser/stmt/function/attributes.test)
Failed asserting that two strings are identical.
--- Expected
+++ Actual
@@ @@
-'array(
-    0: Stmt_Function(
-        byRef: false
-        name: Identifier(
-            name: a
+'Syntax error, unexpected T_SL from 3:1 to 3:2
+Syntax error, unexpected T_STRING, expecting '(' from 4:10 to 4:10
+Syntax error, unexpected '{' from 4:14 to 4:14

I assume the tokens.yaml has to be updated somehow, so T_SL and T_SR are somehow part of attribute grammer, right?

[TomasVotruba]

Thanks! It helped.

1. Now the node attributes are missing in the Attribute node. Any idea how to get them in nodeWithPhpAttributes?

2. Where exactly in the StandardPrinter should be Attribute be printed?

3. Feel free to give feedback on code in overall, I need some guidance.

[TomasVotruba]

I've integreated your comments. It's ready for next review

[nikic]

I pushed a fix for the parser conflicts. Haven't had a chance to review the rest yet.

[TomasVotruba]

Thanks, that helped a lot. I'll continue

[TomasVotruba]

Tests are now broken with some positions. I really don't understand why or how to fix them. Seems like attributes are not parsed anymore

[TomasVotruba]

I tried to rebase on current master.

Could you give this priority? New merged PRs makes this hell to rebase :/

I think only details are missing, but my knowledge of php grammar errors is not that advanced, so I can fix them.

[nikic]

Emulation for new T_ATTRIBUTE token added in f66a32e. I've rebased this PR and fixed the shift-reduce conflicts.

Unfortunately the #[] syntax also has an attribute grouping feature #[Attr1, Attr2], so I think it will be necessary to change the representation, i.e. introduce an additional intermediary AttributeGroup node :/

[nikic]

I've mostly finished this up and merged the initial implementation. One thing that is still missing is full FPPP support.

[ondrejmirtes]

Awesome! 😍

But what's FPPP?

(I'm not afraid to ask the stupid questions.)

[nikic]

FPPP = Formatting-Preserving Pretty Print. It's a bit long to write out :)

[ondrejmirtes]

Oh, of course :)