Improve code style by using CI and pre-commit hooks

[gikari]

The problem

I encountered a problem, when committing a change to the repo: my automatic cargo fmt formatted an unrelated line in the file:

Diff in /lagann/Development/qmetaobject-rs/qmetaobject/src/qtdeclarative.rs at line 506:
 ///
 /// [qt]: https://doc.qt.io/qt-5/qqmlengine.html#qmlRegisterModule
 #[cfg(qt_5_9)]
-pub fn qml_register_module(
-    uri: &CStr,
-    version_major: u32,
-    version_minor: u32,
-) {
+pub fn qml_register_module(uri: &CStr, version_major: u32, version_minor: u32) {
     let uri_ptr = uri.as_ptr();

     cpp!(unsafe [

To commit my changes, I had to exclude the diff above from the git, which is inconvenient.

Apparently, this was left, because there wasn't an automatic check in the CI, when the PR was merged.

Possible solution

• There should be an automatic check in the CI to prevent merging the PR with incorrect code formatting.
• To simplify the life of the developers, there should be a pre-commit hook, that formats the code automatically before committing.

[ratijas]

Not gonna lie, I don't have strong feelings toward auto-formatters when they start acting up and messing with the code in a way that makes it actually less consistent. For this case, I'd rather disable formatting of this signature (or, if possible, forced it to be multi-line), because most things that deal with version_major: u32, version_minor: u32 and stuff are usually long enough to split — especially cpp!() calls.

To simplify the life of the developers, there should be a pre-commit hook, that formats the code automatically before committing.

Pls, no :) Running git commit does not imply that your code/changes will be modified and re-staged, and I'd prefer to keep it that way.

[ratijas]

(I think we are missing an A-Tooling kind of label)

[gikari]

Pls, no :) Running git commit does not imply that your code/changes will be modified and re-staged, and I'd prefer to keep it that way.

The hook can be just a quick check, not necessary a change and stage one. However, as far as I am aware, automatic formatting is one of the primary reasons for git hooks. 🤷

[ratijas]

I prefer automatic checks. In KDE world, for example, clang-format tells you which hunks are misformatted, and suggests to run with --apply flag or something.