The Default Philosophy when OOM

The default behavior is:

• If the binary links against std (typically the case), then print a message to standard error and abort the process. This behavior can be replaced with [set_alloc_error_hook](https://doc.rust-lang.org/std/alloc/fn.set_alloc_error_hook.html) and [take_alloc_error_hook](https://doc.rust-lang.org/std/alloc/fn.take_alloc_error_hook.html). Future versions of Rust may panic by default instead.
• If the binary does not link against std (all of its crates are marked [#![no_std]](https://doc.rust-lang.org/reference/names/preludes.html#the-no_std-attribute)), then call [panic!](https://doc.rust-lang.org/core/macro.panic.html) with a message. The panic handler applies as to any panic.

Rust’s default memory allocation philosophy is to abort (crash) on OOM, not to attempt recovery. This aligns with Rust’s goals of:

• Safety: No undefined behavior or silent corruption.
• Simplicity: No implicit error handling for allocations that rarely fail in practice.
• Performance: Avoid the cost of checking every allocation for Result.

So, when an allocation fails (for example, Vec::push() needs to grow and malloc fails), Rust’s standard library calls the global OOM handler, which by default terminates the program (usually via abort()).