*All PHP versions -sys crate

This crate is meant to facilitate creation of custom PHP extensions in Rust. It provides C bindings for all supported PHP versions.

This crate went through a few iterations, for now its a single crate containing all PHP versions as separate modules - this could change in the future.

In the beginning it also was generating Rust bindings on demand. But currently bindings are meant to be pregenerated - to test if the same crate works on OSX and Windows - without having to vendor OSX and Windows PHP headers.

Its possible we'll need to vendor OSX and Windows PHP includes to fully support these platforms.

Support

PHP Version	Linux	Windows	OSX	ZTS Linux	ZTS Windows
PHP 5.4	Yes
PHP 5.5
PHP 5.6	Yes			Yes
PHP 7.0	Yes
PHP 7.1	Yes
PHP 7.2	Yes
PHP 7.3	Yes
PHP 7.4	Yes
PHP 8.0	Yes
PHP 8.1	Yes
PHP 8.2	Yes
PHP 8.3	Yes
PHP 8.4	Yes
PHP 8.5	Yes

Example extension — one .so that loads on every PHP 8.x

example-ext/ is a complete, loadable PHP extension that is built once into a single .so and loads unchanged into every supported PHP 8.x (8.0–8.5). It exports two userland functions and a phpinfo() section:

php_all_sys_hello();     // "Hello from Rust 🦀 — single .so, loaded into PHP with Zend API 20230831"
php_all_sys_zend_api();  // 20230831  (the host's Zend module API, detected at load time)

When PHP loads a .so it validates two fields of the module entry byte-for-byte — the Zend module API number (==) and the build id (strcmp) — so a module with those values baked in at compile time loads on exactly one PHP minor. Instead of baking them in, this extension reads them from the host at load time: PHP registers its built-in modules (ext/standard, Core, …) into the exported module_registry before it loads any external extension, and each one carries the running engine's exact zend_api, build_id, zts, zend_debug and size. get_module() reads one of them and echoes those fields, so the load-gate matches on every version — NTS/ZTS/debug suffixes handled for free.

The only ABI shape that actually changed across 8.x is zend_function_entry (32 bytes on 8.0–8.3, 48 bytes on 8.4+, which appended two fields); its stride is picked at runtime from the detected API number. Every other type the code touches is byte-identical across 8.x, so a single php-all-sys binding is ABI-correct for all of them and the code never names a concrete version.

Build it once and load it into any PHP 8.x:

cargo build --release --manifest-path example-ext/Cargo.toml   # no feature flags
php -d extension=target/release/libphp_all_sys_example.so \
    -r 'echo php_all_sys_hello(), "\n";'                       # works on 8.0 … 8.5

CI proves the claim: a build-universal job compiles the .so once and uploads it, then a load matrix over PHP 8.0–8.5 downloads that same artifact, loads it into each real PHP, and runs example-ext/tests/smoke.php — which asserts the extension loaded and that the Zend API it detected is the one the running PHP actually uses.

Generating bindings

private crate sys-build can be installed and used to generate binding files

cargo install --path sys-build
cargo php-sys-build # to generate files, should be run from Crates root dir
cargo fmt # to format generated files before commiting