fix(codegen): write output file when contents change

[brian14708]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Docs
• New Binding issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes, and the changes were approved in issue #___
• No

Checklist

• When resolving issues, they are referenced in the PR's title (e.g fix: remove a typo, closes #___, #___)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• I have added a convincing reason for adding this feature, if necessary

Other information

Currently an app build is needed even when no code has changed. After some investigation, it was trigger by the writing of the temporary icon file used for embedding.

Even with this change, two builds are required to avoid further rebuilds. Maybe it's better to preprocess the icons in build.rs?

[lucasfernog]

Clever one, thanks!

[lucasfernog]

Even with this change, two builds are required to avoid further rebuilds. Maybe it's better to preprocess the icons in build.rs?

We have a way to do this, enabling the codegen feature of tauri-build and changing your build.rs to:

fn main() {
  let mut codegen = tauri_build::CodegenContext::new();
  if !cfg!(feature = "custom-protocol") {
    codegen = codegen.dev();
  }
  codegen.build();
  tauri_build::build()
}

then change tauri::generate_context!() to tauri::tauri_build_context!().

aaaaaaaactually this has a bug, i'll open a PR to fix it.