Use Qt's public logging APIs rather than undocumented internals

[jnbooth]

Instead of exposing undocumented internal features of Qt, qtlogging.rs now exports q_critical, q_debug, q_fatal, q_info, and q_warning, equivalent to Qt's qCritical, qDebug, qFatal, qInfo, and qWarning. So instead of doing this:

qt_message_output(
  QtMsgType::QtInfoMsg,
  &QMessageLogContext::new(c"myfile.rs", 1, c"", c"default"),
  &QString::from(&format!("Test message: {x} / {y}"))
);

You can simply do this:

q_info!("Test message: {x} / {y}");

The file and line number are automatically filled in by the file and line built-in macros.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (c6710b7) to head (0f31a78).

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1300   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           75        75           
  Lines        12772     12772           
=========================================
  Hits         12772     12772           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[LeonMatthesKDAB]

Hi @jnbooth,
overall I'm in favor of adding the appropriate logging functions.
However, I think the internal API that was already exposed should not be removed.

The internal API is suited to a different use-case and allows more fine-grained access.
One good use-case for it would be to implement a custom log backend with the Qt logging infrastructure.
This would be quite difficult with just q_info!, etc.

So please add the already exposed API back.

[jnbooth]

@LeonMatthesKDAB Do you mean something like qInstallMessageHandler? Whatever your use case is, I think there will be a way to do it using Qt's public API rather than undocumented internals.

[LeonMatthesKDAB]

I actually mean the other way around :)

What you're referring to is installing a custom log handler in Qts logging system.

What I was referring to is installing Qts logging system as a custom log handler in Rusts log ecosystem (e.g. the log crate )

[jnbooth]

@LeonMatthesKDAB Looking at their docs, I think you would do it like this:

use std::ffi::CString;
use cxx_qt_lib::{QString, q_critical, q_debug, q_fatal, q_info, q_warning};
use log::{Level, Log, Record};

struct QtLogger;

impl Log for SimpleLogger {
    fn log(&self, record: &Record) {
        let file = CString::new(record.file().unwrap_or_default());
        let line = record.line().unwrap_or_default() as i32;
        let message = QString::from(record.args());
        match record.level() {
            Level::Error => q_critical(file.as_ptr(), line, &message),
            Level::Warn => q_warn(file.as_ptr(), line, &message),
            Level::Info => q_info(file.as_ptr(), line, &message),
            Level::Debug | Level::Trace => q_debug(file.as_ptr(), line, &message),
        }
    }
}

No need for undocumented internals.