[GCC 15] Zero-sized array errors in wayland protocol sources

[frosthecker]

Context

While compiling Hyprland on GCC 15 (Ubuntu 25.10 ARM64), I ran into multiple build errors due to zero-sized arrays in the generated Wayland protocol sources under protocols/.

These files are generated automatically by wayland-scanner. Earlier, GCC 13 and 14 treated these lines as mere warnings, but, GCC 15 now treats these empty [] definitions as errors instead of warnings.

Example error

protocols/wayland.cpp:123:13: error: ISO C++ forbids zero-size arrays [-Wpedantic]
273 | uint8_t data[];
| ^~~~

Temporary Workaround

uint8_t data[1]; or uint8_t data[nullptr];

in all affected files allows the build to complete successfully.
After this change, Hyprland builds fine and runs normally with GCC 15.

System details

OS: Ubuntu 25.10 (Questing Quokka) ARM64

Compiler: GCC 15.2.0

Build system: CMake + Ninja

Repo branch: main

Suggestion

Since these files are generated by wayland-scanner, it might make sense to:

Adjust Hyprland’s CMake generation step,

or

Add a small post-processing patch replacing [] with [1] or [nullptr] after the scanner runs.
This would ensure GCC 15 compatibility without changing upstream Wayland sources.

TL;DR

GCC 15 disallows zero-length arrays in auto-generated protocol C++ sources.
Temporary fix: change [] → [1] or [nullptr].
Build then succeeds normally.

Would the maintainers prefer I open a PR with a small CMake post-processing patch for this?

Thanks 🙏

— @frosthecker

[Honkazel]

Isn't that fixed in hyprwayland-scanner 0.4.5?

[frosthecker]

Could you confirm which commit or release tag includes the fix for the zero-sized arrays?

[vaxerski]

he literally told you.