Add PHP 5.6 WebAssembly build support for legacy WordPress versions

[adamziel]

Summary

• Add build system support for compiling PHP 5.6 to WebAssembly, enabling WordPress Playground to run WordPress 1.x through 4.x
• PHP 5.6 is backward compatible with PHP 5.2 code, so a single legacy version covers all older WordPress releases that require PHP 5.2+
• Modify the Dockerfile and C source extensions with PHP 5.x version guards and compatibility stubs
• Add dedicated legacy PHP test suite (separate from the main PHP 7.4-8.5 test matrix)

Changes

Build system (Dockerfile + C sources):

• Add PHP 5.x version guards for fiber-asm, imagick, chunk-alloc patches, ASM arithmetic, cli_server
• Port proc_open, dns_polyfill, post_message_to_js, and wasm_memory_storage extensions for PHP 5.x compatibility
• Create php5.6.patch for Emscripten-specific fixes
• Make apply-mysqlnd-patch.sh tolerant of PHP 5.x (different API)

Package scaffolding:

• packages/php-wasm/node-builds/5-6/ and web-builds/5-6/ with full NX project configuration
• Add case '5.6' to node and web getPHPLoaderModule() loader modules
• Add LegacyPHPVersions export (separate from SupportedPHPVersions to avoid test regressions)
• Add tsconfig.base.json path aliases for new packages

Test suite:

• legacy-php-versions.spec.ts with 12 tests covering: version verification, execution, file I/O, networking, proc_open, SQLite, JSON, sessions, mbstring, error handling, memory, and filesystem
• Completely separate from the main test matrix — runs independently

Next step: compile WASM binaries

The WASM binaries must be compiled in a Docker-enabled environment:

node packages/php-wasm/compile/build.js --PLATFORM=node --PHP_VERSION=5.6 --WITH_IMAGICK=no --WITH_OPCACHE=no
node packages/php-wasm/compile/build.js --PLATFORM=web --PHP_VERSION=5.6 --WITH_IMAGICK=no --WITH_OPCACHE=no

Test plan

• Existing PHP 7.4-8.5 tests pass (769 passed, 1 pre-existing flaky timing test)
• TypeScript typecheck passes for php-wasm-universal and php-wasm-node
• Lint passes for php-wasm-node
• NX recognizes new php-wasm-node-5-6 and php-wasm-web-5-6 projects
• Compile PHP 5.6 WASM binaries (requires Docker)
• Run legacy test suite against compiled binaries
• Test WordPress 4.x, 3.x, 2.x, 1.x on PHP 5.6

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR adds build system support for compiling PHP 5.6 to WebAssembly, enabling WordPress Playground to run legacy WordPress versions (1.x through 4.x) that require PHP 5.2+. PHP 5.6 is backward compatible with PHP 5.2 code, providing a single legacy binary for all older WordPress releases.

Changes:

• Added PHP 5.x version guards and compatibility stubs to C extensions (proc_open, dns_polyfill, post_message_to_js, wasm_memory_storage)
• Created NX project scaffolding for @php-wasm/node-5-6 and @php-wasm/web-5-6 packages
• Added separate legacy PHP test suite with 12 tests covering core functionality

Reviewed changes

Copilot reviewed 29 out of 29 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tsconfig.base.json	Added TypeScript path aliases for PHP 5.6 node and web packages
packages/php-wasm/web/src/lib/get-php-loader-module.ts	Added case '5.6' to web loader module switch
packages/php-wasm/node/src/lib/get-php-loader-module.ts	Added case '5.6' to node loader module switch
packages/php-wasm/universal/src/lib/supported-php-versions.ts	Added LegacyPHPVersions export and type
packages/php-wasm/universal/src/lib/index.ts	Exported LegacyPHPVersions and LegacyPHPVersion type
packages/php-wasm/supported-php-versions.mjs	Added PHP 5.6 entry to phpVersions array
packages/php-wasm/node/src/test/legacy-php-versions.spec.ts	Created comprehensive test suite for legacy PHP versions
packages/php-wasm/web-builds/5-6/*	Created complete package structure for web PHP 5.6 build
packages/php-wasm/node-builds/5-6/*	Created complete package structure for node PHP 5.6 build
packages/php-wasm/compile/php/proc_open.*	Added PHP 5.x stub implementation for proc_open functions
packages/php-wasm/compile/php/php5.6.patch	Added PHP 5.6-specific patch for empty file copy issue
packages/php-wasm/compile/php/apply-mysqlnd-patch.sh	Made script tolerant of missing mysqlnd in PHP 5.x
packages/php-wasm/compile/php/Dockerfile	Added version guards for fiber-asm, imagick, chunk-alloc, asm arithmetic, and cli_server
packages/php-wasm/compile/php-wasm-memory-storage/wasm_memory_storage.c	Added PHP 5.x no-op implementation
packages/php-wasm/compile/php-wasm-dns-polyfill/dns_polyfill.c	Added PHP 5.x compatibility with TSRMLS_CC and type adjustments
packages/php-wasm/compile/php-post-message-to-js/post_message_to_js.c	Added PHP 5.x compatibility for string return handling

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[mho22]

@JanJakes Do you think we can close this pull request now that you implemented 5.2 ?

[JanJakes]

@mho22 Yes, I missed this one. Thanks for noticing! Closing in favor of #3490.