How would i run a Rust program without a window only when it's in release mode [duplicate]

Question

I have a Rust project I'm currently working on and I frequently have to debug and deploy it. While it's deployed it runs in the background without a window but when I'm debugging I want a window to see if there are any runtime errors.

I currently use #![windows_subsystem = "windows"] and comment it out whenever I'm debugging, but is there a way for the program itself to check if it's in debug mode so it doesn't use that flag?

Answer 1

You can use #![cfg_attr(predicate, attribute)] to only compile with an attribute if the specific predicate evaluates to true.

As for what the predicate is, my recommendation would be use an explicit feature (e.g. console) that you set when you want to build with the non-default behavior (e.g. having the console window appear).

Additionally, if you want to have your code be portable, you should also check that you are compiling for Windows.

In Cargo.toml:

[features]
console = []

In main.rs:

#![cfg_attribute(
  all(
    target_os = "windows",
    not(feature = "console"),
  ),
  windows_subsystem = "windows"
)]

Then you can compile or run with --features console to have the default console subsystem be used instead.

---

If you want to actually check for the debug mode, the closest you can get is the debug_assertions predicate, which is enabled by default when compiling without optimizations.