Very interesting, I had no idea that lld could link MinGW and MSVC objects together. This links against php8embed.lib?

Mingw isn't used at all with this patch. Everything uses Visual Studio.
For cgo, it uses the clang version provided by VS, which has a VS backend (needs Go 1.26, I stumbled upon this undocumented Google patch very recently).

php8embed.dll is not even needed, only php8ts.dll is needed, because I disabled the php-cli subcommand.

Locally, I even manage to run php-cli, but this requires manually compiling PHP to enable the embed SAPI, so I disabled it for now because both php8ts.dll and php.exe are shipped with the official PHP package.

I also have a patch for Static PHP CLI, but it's not working because the PHP source code and Makefile on Windows doesn't support building a static version of php8ts.dll and php8embed.dll. Patching the PHP source code will be necessary.

For cgo, it uses the clang version provided by VS, which has a VS backend (needs Go 1.26, I stumbled upon this undocumented Google patch very recently).

That's the part I was missing, thank you!

Gave it a shot and updated your initial post for instructions, however, once it attempts to serve a php file with .\frankenphp.exe php-server --root=./ the app stops.

Have you copied all the necessary DDLs in the same directory?

Shouldn't be necessary with

$env:PATH += ";$env:VCPKG_ROOT\installed\x64-windows\bin"
$env:PATH += ";C:\watcher-x86_64-pc-windows-msvc"
$env:PATH += ";C:\php-8.5.1-Win32-vs17-x64"

Is anything else required?

You must also add $env:PATH += ";C:\php-8.5.1-Win32-vs17-x64\lib".

Same issue, I don't think it could be related to libraries anyway, as it would fail to run in the first place then. Shared libraries are (by default) loaded at initialisation time and we're not passing delayload arguments to the compilation.

Log:

❯❯ frankenphp git:(windows) 21:46 .\frankenphp.exe php-server --root=./
2026/01/10 20:46:22.912 WARN    admin   admin endpoint disabled
2026/01/10 20:46:22.912 INFO    tls.cache.maintenance   started background certificate maintenance      {"cache": "0x2e61d3850500"}
2026/01/10 20:46:22.912 WARN    http.auto_https server is listening only on the HTTP port, so no automatic HTTPS will be applied to this server {"server_name": "php", "http_port": 80}
2026/01/10 20:46:22.949 INFO    frankenphp      FrankenPHP started 🐘   {"php_version": "8.5.1", "num_threads": 64, "max_threads": 64}
2026/01/10 20:46:22.950 WARN    http    HTTP/2 skipped because it requires TLS  {"network": "tcp", "addr": ":80"}
2026/01/10 20:46:22.950 WARN    http    HTTP/3 skipped because it requires TLS  {"network": "tcp", "addr": ":80"}
2026/01/10 20:46:22.950 INFO    http.log        server running  {"name": "php", "protocols": ["h1", "h2", "h3"]}
2026/01/10 20:46:22.951 INFO    Caddy serving PHP app on :80
2026/01/10 20:46:22.953 INFO    tls     storage cleaning happened too recently; skipping for now        {"storage": "FileStorage:C:\\Users\\m\\AppData\\Roaming\\Caddy", "instance": "489ade52-21ab-40c6-b18a-2932fb8eab4d", "try_again": "2026/01/11 20:46:22.953", "try_again_in": 86400}
2026/01/10 20:46:22.953 INFO    tls     finished cleaning storage units
❯❯ frankenphp git:(windows)  21:46

Text files like an index.html page are served just fine. Only when php is attempted to be executed does the program simply stop.

I didn't try the php-server command yet, only run with a custom Caddyfile.
Are the tests green? (They are on my local installation)

Could you also show me the content of your PHP script?

Content of the php script:

<?php
echo phpinfo();

I haven't ran the test suite yet, but frankenphp run shows the same behaviour.

Here is a build I created locally: https://drive.google.com/file/d/1B09de1rERpRUN-bnAje0K2vHcwhVoDJa/view?usp=sharing
It's the official PHP binary distribution with FrankenPHP itself and the extra needed DLLs added.

On my computer, it runs Symfony without issue @henderkes.

Thanks, I'll try this one and report back.

Edit: it's working, but it was linked against 8.5.3-dev. I'll try to link against 8.5.1 again and see if I can get anywhere after the new commits.

Okay, I guess I figured it out? When I move it into the php folder it works, so I'm guessing php is trying to load something in the background but silently fails. Extensions would come to mind, but I'm not loading any.