Build Error: watcher.c cannot find wtr/watcher-c.h (FrankenPHP v1.7.0 and main branch)

[markc]

I'm trying to build a custom FrankenPHP binary on CachyOS (Arch Linux derivative) that includes the cloudflare DNS module, using xcaddy.

I'm consistently encountering a build error related to the internal watcher.c file trying to include a missing header.

Environment:

• OS: CachyOS (Arch Linux derivative)
• Go Version: go1.24.4
• PHP Version: 8.4.8 (php-config is working correctly)
• FrankenPHP Source: Cloned directly from https://github.com/dunglas/frankenphp.git
• xcaddy command used:

  CGO_ENABLED=1 \
  CGO_CFLAGS="$(php-config --includes)" \
  CGO_LDFLAGS="$(php-config --ldflags)$(php-config --libs)" \
  xcaddy build \
  --output frankenphp_custom \
  --with github.com/dunglas/frankenphp \
  --with github.com/caddy-dns/cloudflare

  (Also tried go build with custom main.go and replace directives, leading to the same C compilation error.)

Problem Description:

During the build process, the C compiler fails with a fatal error: wtr/watcher-c.h: No such file or directory in internal/watcher/watcher.c.

Error Output:

# github.com/dunglas/frankenphp/internal/watcher
watcher.c:5:10: fatal error: wtr/watcher-c.h: No such file or directory
    5 | #include "wtr/watcher-c.h"
      |          ^~~~~~~~~~~~~~~~~
compilation terminated.

What I've investigated/verified:

1. File Presence: I've confirmed that internal/watcher/wtr/watcher-c.h does not exist in the cloned repository (neither in v1.7.0 tag nor main branch after git pull).
   • ls -l internal/watcher/ shows only watcher.h, watcher.c, etc., but no wtr/ subdirectory.
   • ls -l internal/watcher/wtr/ returns "No such file or directory".
2. watcher.c Content: The watcher.c file explicitly includes "wtr/watcher-c.h" on line 5.
3. php-config: CGO_CFLAGS and CGO_LDFLAGS are correctly set via php-config.
4. systemd-logind/AppArmor: These are running correctly and not showing any related errors.
5. Go Module Resolution: When building from a separate directory (with correct replace directive in the custom go.mod), go list -f '{{.Dir}}' github.com/dunglas/frankenphp correctly points to the local cloned repository (/home/markc/Dev/frankenphp), so the build should be using the local source.

Conclusion:

It appears there's a mismatch in the FrankenPHP source code itself (at least in v1.7.0 and main branch as of today, July 1st, 2025). The watcher.c file is attempting to include a header (wtr/watcher-c.h) that does not exist at the expected path within the repository's internal structure. It seems watcher.h is present at internal/watcher/watcher.h, but is not being included correctly or doesn't contain the necessary definitions.

Could you please advise on how to resolve this? Is there a missing file, an incorrect include path in watcher.c, or a specific build step/dependency for this wtr component that I'm overlooking?

[dunglas]

Watcher is an external library that must be installed separately. Alternatively, use the nowatcher build tag to disable watcher support.

https://frankenphp.dev/docs/compile/#install-optional-dependencies