Support PHP 8.6

[rlerdorf]

Support PHP 8.6

Add compatibility shims in php_ast.h for the internal Zend API changes in PHP 8.6:

• ZEND_AST_METHOD_REFERENCE was renamed to ZEND_AST_TRAIT_METHOD_REFERENCE
• The _throw() ZPP variants were removed; plain ZPP now always throws, so zend_parse_parameters_throw maps to zend_parse_parameters and the removed ZEND_PARSE_PARAMS_THROW flag is defined to 0 (the throwing default).

All guarded on PHP_VERSION_ID >= 80600, so older versions are unaffected and the userland ast\AST_METHOD_REFERENCE constant is unchanged.

New 8.6 feature: doc comments on parameters

Of the implemented PHP 8.6 RFCs, only Add DocComments for function parameters is a parser change that affects the AST; the rest are library functions, new built-in enums, and reflection/runtime/ini/stream changes that don't touch the parse tree.

AST_PARAM already has a docComment child (index 4), which was always null before 8.6. It is now populated by the parser for parameters carrying a doc comment, with no extension changes required. The output matches the engine's own ReflectionParameter::getDocComment() (including the before-vs-after-parameter comment behavior), and older AST versions are unaffected.

tests/php86_param_doc_comments.phpt is added as a version-gated regression test (skips on PHP < 8.6), covering doc comments on both function parameters and property-hook parameters.

CI

There is no published php:8.6 docker image yet, so 8.6 could not be added to the previous docker-based test matrix. CI now uses shivammathur/setup-php for all PHP versions (7.2–8.6) in a single matrix, replacing the docker-based setup. 8.6 is built from php-src master and marked continue-on-error since it is still in development and is a moving target. The package.xml validation previously run in ci/test_inner.sh is preserved as a pecl package step, and the now-unused ci/ docker scripts are removed.

Testing

Built against PHP 8.6.0-dev and ran the full suite: 95 passed, 0 failed, 2 skipped (the skipped tests are version-gated). The build and existing tests continue to pass on earlier PHP versions.

[nikic]

This looks fine to me, but I wonder if it wouldn't make sense to just use shivammathur/setup-php for all PHP versions, instead of having two different CI setups?

[nikic]

I'd prefer to not continue on error. Better to ignore the error than not see it at all.

[rlerdorf]

You are right. Dropped continue-on-error. The 8.6 job will now show a real (red) failure when php-src master breaks something, while fail-fast: false keeps it from cancelling the other versions.

[rlerdorf]

Consolidated everything onto shivammathur/setup-php in a single 7.2–8.6 matrix and dropped the docker-based setup. The package.xml check that ci/test_inner.sh did is preserved as a pecl package step, and the now-unused ci/ scripts are removed. 8.6 builds from php-src master so it's marked continue-on-error.