Allow customizing output of `godot_{warn,error}!`

[jjant]

Hi, we use tracing in my project for logging.

I whipped up a quick tracing subscriber that routes tracing logs to Godot via godot_{print,warn,error}! (corresponding to the tracing log levels info and lower, warn, and error, respectively).

Info levels get printed fine:

However, I have a couple issues with warn/error logs (in the screenshot, I'm using push_warning for warnings, and godot_error! for errors):

• With push_warning:

  • the message includes the push_warning: string, which I don't want. I see that some built-in warnings in Godot don't include that, so it might be possible.
  • the stack trace points to variant_utility.cpp:1118, I want to customize that to point to my code (which I can since tracing makes that information available to me)

• With godot_error!/godot_warn!:

  • The message includes the (fully qualified) name of writer which calls godot_error!, I want to instead point to my code which called tracing::error!.
  • The stack trace is equally "wrong".

[Bromeon]

With push_warning:

• the message includes the push_warning: string, which I don't want. I see that some built-in warnings in Godot don't include that, so it might be possible.
• the stack trace points to variant_utility.cpp:1118, I want to customize that to point to my code (which I can since tracing makes that information available to me)

push_warning is not a function we implement -- we just forward the FFI call to the Godot engine. So changing its behavior is something you'd need to bring up with Godot itself.

---

• With godot_error!/godot_warn!:

  • The message includes the (fully qualified) name of writer which calls godot_error!, I want to instead point to my code which called tracing::error!.
  • The stack trace is equally "wrong".

The function description is passed here:

gdext/godot-core/src/global/print.rs

Line 36 in 18d8a22

let function = format!("{}\0", $crate::inner_function!());

What if we provided an additional overload of the macros with a target keyword, similar to the log crate?

godot_error!(target: some_string; "format {s}", s = value);

Would you like to work on a pull request for this?

[jjant]

Hey @Bromeon, thanks for the quick response.

What if we provided an additional overload of the macros with a target keyword, similar to the log crate?

I think that would work, but for these customized use cases I think that exposing a Rust version of gdextension_print_warning/gdextension_print_warning_with_message directly would give more control (and is less syntax to learn).

What do you think?

[Bromeon]

Not sure -- there are already a lot of APIs for error reporting:

• push_error utility function
• godot_error! macro
• godot_script_error! macro

Now adding a fourth isn't really less syntax to learn. It's also lower-level, harder to discover and doesn't provide string formatting.

If the concern is that users would need to do lots of formatting for file!(), line!() etc, we can also let the macro take a struct -- possible even reuse std::panic::Location.

Also, I wonder if we can keep some consistency between info (print), warn and error APIs -- because info doesn't allow specifying source location, as far as I can tell? 🤔