feat: static build support (--enable-php-debugger) - #47

Adds support for compiling php_debugger as a static extension into php-src, producing a single binary with the debugger built in — no .so required.

Fixes #40

Usage

In-tree (php-src)

# Symlink or copy into php-src/ext/
ln -s /path/to/php-debugger ext/php_debugger

# Build
./buildconf --force
./configure --enable-php-debugger [other flags...]
make -j$(nproc)

# Verify
./sapi/cli/php -m | grep php_debugger

static-php-cli

Also verified with static-php-cli — produces a fully static, zero-dependency binary:

$ file php
ELF 64-bit LSB executable, x86-64, statically linked, stripped

$ ls -lh php
4.6M

$ ./php -v
PHP 8.4.20 (cli) (NTS x86_64-linux-musl-gcc)
Built by static-php-cli 2.8.5
Zend Engine v4.4.20
    with PHP Debugger v0.1.0-dev

$ ./php -r "var_dump(extension_loaded('php_debugger'), extension_loaded('xdebug'));"
bool(true)
bool(true)

static-php-cli recipe will be submitted as a separate PR.

Changes

• MINIT self-registration — In static builds, zend_startup_extensions() has already run by MINIT time, so we register the Zend extension manually from PHP_MINIT_FUNCTION and call the startup functions inline
• xdebug_zend_startup() guard — Early return in static builds to prevent double module registration when zend_startup_extensions() calls it after MINIT
• php_php_debugger.h — Bridge header providing phpext_php_debugger_ptr for PHP's static extension table (main/internal_functions.c)
• config.m4 — Add PHP_ADD_INCLUDE for header discovery
• ZTS fix — COMPILE_DL_XDEBUG → COMPILE_DL_PHP_DEBUGGER in RINIT
• CI — Dedicated static-build.yml workflow: builds PHP from source with --enable-php-debugger, runs smoke tests. Only triggers on changes to static-build-related files.

Benchmark (PHP 8.6.0-dev, bench.php, Linux x86_64)

Same observer API floor as the shared build.

Compatibility

• extension_loaded("php_debugger") ✅
• extension_loaded("xdebug") ✅ (compat alias)
• All php_debugger.* and xdebug.* INI settings work
• Shared builds (zend_extension=php_debugger.so) unaffected
• Verified with static-php-cli (musl, fully static, 4.6 MB)