June 12, 2026
Before main, before calm
There Is Life Before Main in Rust
Rust fans lose it over secret startup magic and the AI disclaimer drama
TLDR: The post reveals that Rust programs do important setup work before the part most people think of as the true start, and that hidden phase can be useful. Commenters were split between praising the article’s AI-use honesty, groaning about AI being everywhere, and making jokes about “before main” sounding like ancient Rust history.
A deeply nerdy post about what happens before a Rust program even reaches its main function somehow turned into a mini comment-section soap opera. The article itself, from the creator of Rust’s ctor crate, explains that programs do a surprising amount of setup work before your code officially starts. In plain English: your app is already busy backstage before the curtain rises, and the author wants developers to use that hidden moment for smarter setup tricks.
But the crowd? Oh, the crowd had opinions. The strongest reaction was a mix of respect, nitpicking, and AI exhaustion. One commenter loved the author’s unusually explicit note about how AI tools were used, basically saying, yes please, make this the standard everywhere. Another instantly rolled their eyes and fired back that apparently everything involving Rust now has to mention AI somehow. That tiny disclaimer sparked more drama than the low-level startup mechanics themselves.
Then came the classic engineer flexing: one commenter argued this isn’t really about Rust at all, but about understanding how programs start on Linux and beyond — a subtle but very real “let’s zoom out and be precise here” correction. And of course the thread got its joke in: one person admitted they clicked expecting prehistoric Rust from before the main branch existed. So yes, the article is about hidden startup code — but the real entertainment is watching the community debate whether the coolest part was the programming trick, the AI honesty, or the pun potential.
Key Points
- •The article explains that Rust program execution begins before user-defined `fn main()` through runtime startup code.
- •key The Rust runtime is described as being built on top of the C runtime, which integrates program code with the operating system.
- •The pre-main phase is used to initialize services such as panic handling, unwinding, and argument translation into `std::env::args`.
- •The article argues that pre-main execution offers a deterministic, single-threaded environment suitable for reliable initialization and bootstrapping.
- •It describes low-level startup on Linux, where the ELF header’s `e_entry` field typically points to `_start`, with similar platform hooks existing on Windows.