Stack overflow using `1.94.0-nightly (2c283a9a5 2025-12-04)`

[frederikhors]

Using the cargo 1.94.0-nightly (2c283a9a5 2025-12-04) coming from the cargo 1.93.0-nightly (2d4fa1395 2025-11-12) I get a stack overflow issue on Windows 11 using the same identical codebase.

[bjorn3]

Is this a stack overflow at compile time or at runtime? If the former do you have a backtrace? If the latter is it possible that you were already almost getting a stack overflow before but the update caused slightly higher stack usage?

[frederikhors]

Sorry, I should have been more precise.

I run the (simple Axum web server) with cargo-clif run.

The stack overflow happens calling a route of the Axum web server.

I swap the cargo-clif files, cargo clean and the same code with the same Axum route panics with stack overflow.

If I use old cargo-clif files it works.

Is there a new reduction in stack size?

[bjorn3]

Can you try running with RUST_MIN_STACK=16777216 to grow the stack for spawned threads from 2MB to 16MB?

[frederikhors]

I'll try in a few moments, but has the default stack size changed?

[bjorn3]

It hasn't afaik. But stack usage can change between compiler versions. An optimization may make things less stack, while a refactor in the standard library or the way things are lowered can increase stack usage (especially in unoptimized builds)

[frederikhors]

I tried using:

$env:RUST_MIN_STACK="16777216" && cargo-clif run

and I get:

thread 'tokio-runtime-worker' (12372) has overflowed its stack

on many routes. This scares me a lot!

[frederikhors]

I used this code:

dbg!(&stacker::remaining_stack());

in the beginning of the axum route handler. These are the results:

• previous (cargo 1.93.0-nightly (2d4fa1395 2025-11-12)):

[src\list.rs:25:9] &stacker::remaining_stack() = Some(311056)

• latest version (1.94.0-nightly (2c283a9a5 2025-12-04)):

[src\list.rs:25:9] &stacker::remaining_stack() = Some(274800)

• default cargo (NOT clif) (--version: cargo 1.91.1 (ea2d97820 2025-10-10))

[src\list.rs:25:9] &stacker::remaining_stack() = Some(268896)

I'm a little freaked out by the 36+ KB (!) (311056 - 274800) difference between two different versions a month apart!

I think something's strange, right?