stack overflow while compiling async recursion

[ehaydenr]

Compiler encounters segfault when compiling the below code

Code

struct Wrapper<T>(T);

pub async fn f1() {
    f2(Wrapper(())).await
}

pub async fn f2<T>(stream: T) {
    Box::pin(f2(Wrapper(stream))).await
}

Meta

$ cargo version
cargo 1.86.0 (adf9b6ad1 2025-02-28)
$ cargo +nightly version
cargo 1.88.0-nightly (7918c7eb5 2025-04-27)

Error output

Stable

error: rustc interrupted by SIGSEGV, printing backtrace

/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x2fa1b74)[0xffffaf891b74]
linux-vdso.so.1(__kernel_rt_sigreturn+0x0)[0xffffb09f17ac]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(_RNvNtNtCs1eHWH1cD26q_17rustc_codegen_ssa9debuginfo10type_names14push_item_name+0x26c)[0xffffade124c8]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(_RNvNtNtCs1eHWH1cD26q_17rustc_codegen_ssa9debuginfo10type_names14push_item_name+0x164)[0xffffade123c0]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151d7f8)[0xffffade0d7f8]

### cycle encountered after 5 frames with period 6
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]
### recursed 41 times

/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]
/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/librustc_driver-d10e1ea80d090031.so(+0x151cf78)[0xffffade0cf78]

note: rustc unexpectedly overflowed its stack! this is a bug
note: maximum backtrace depth reached, frames may have been lost
note: we would appreciate a report at https://github.com/rust-lang/rust
help: you can increase rustc's stack size by setting RUST_MIN_STACK=16777216
note: backtrace dumped due to SIGSEGV! resuming signal
error: could not compile `segfault` (lib)

Caused by:
  process didn't exit successfully: `/usr/local/rustup/toolchains/stable-aarch64-unknown-linux-gnu/bin/rustc --crate-name segfault --edition=2024 src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=310 --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values())' -C metadata=d1c27d02b862a57e -C extra-filename=-f2d1ad9e2f73cb97 --out-dir /workspaces/rust/segfault/target/debug/deps -C incremental=/workspaces/rust/segfault/target/debug/incremental -L dependency=/workspaces/rust/segfault/target/debug/deps` (signal: 11, SIGSEGV: invalid memory reference)

Nightly

error: rustc interrupted by SIGSEGV, printing backtrace

/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/librustc_driver-121983e25d0fab07.so(+0x31b2310)[0xffffb5ef2310]
linux-vdso.so.1(__kernel_rt_sigreturn+0x0)[0xffffb714e7ac]
/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/librustc_driver-121983e25d0fab07.so(_RNvNtNtCsiqNB9qq6D9S_17rustc_codegen_ssa9debuginfo10type_names14push_item_name+0x4)[0xffffb4543080]
/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/librustc_driver-121983e25d0fab07.so(+0x17fe368)[0xffffb453e368]

### cycle encountered after 4 frames with period 5
/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/librustc_driver-121983e25d0fab07.so(+0x17fd8f0)[0xffffb453d8f0]
/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/librustc_driver-121983e25d0fab07.so(+0x17fd8f0)[0xffffb453d8f0]
/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/librustc_driver-121983e25d0fab07.so(+0x17fd8f0)[0xffffb453d8f0]
/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/librustc_driver-121983e25d0fab07.so(+0x17fd8f0)[0xffffb453d8f0]
/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/librustc_driver-121983e25d0fab07.so(+0x17fd8f0)[0xffffb453d8f0]
### recursed 50 times

/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/librustc_driver-121983e25d0fab07.so(+0x17fd8f0)[0xffffb453d8f0]
/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/librustc_driver-121983e25d0fab07.so(+0x17fd8f0)[0xffffb453d8f0]

note: rustc unexpectedly overflowed its stack! this is a bug
note: maximum backtrace depth reached, frames may have been lost
note: we would appreciate a report at https://github.com/rust-lang/rust
help: you can increase rustc's stack size by setting RUST_MIN_STACK=16777216
error: could not compile `segfault` (lib)

Caused by:
  process didn't exit successfully: `/usr/local/rustup/toolchains/nightly-aarch64-unknown-linux-gnu/bin/rustc --crate-name segfault --edition=2024 src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=310 --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values())' -C metadata=6efcc8920530f666 -C extra-filename=-ca85f3463d939f74 --out-dir /workspaces/rust/segfault/target/debug/deps -C incremental=/workspaces/rust/segfault/target/debug/incremental -L dependency=/workspaces/rust/segfault/target/debug/deps` (signal: 11, SIGSEGV: invalid memory reference)

[workingjubilee]

huh, some obvious recursion but otherwise I think that's a genuinely novel report. fascinating! thanks!

[moxian]

rustc printed a nice error message prior to nightly-2024-01-10 (1.77.0):

error[E0733]: recursion in an `async fn` requires boxing
 --> src\lib.rs:7:1
  |
7 | pub async fn f2<T>(stream: T) {
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ recursive `async fn`
  |
  = note: a recursive `async fn` must be rewritten to return a boxed `dyn Future`
  = note: consider using the `async_recursion` crate: https://crates.io/crates/async_recursion

For more information about this error, try `rustc --explain E0733`.
error: could not compile `mycrate` (lib) due to 1 previous error

PRs in nightly-2024-01-10

PRs in range:
  - #119606 (Consuming `emit`) by nnethercote
  - #119754 (Rollup of 10 pull requests) by matthiaskrgr
    - #118903 (Improved support of collapse_debuginfo attribute for macros.)
    - #119033 (coverage: `llvm-cov` expects column numbers to be bytes, not code points)
    - #119598 (Fix a typo in core::ops::Deref's doc)
    - #119660 (remove an unnecessary stderr-per-bitwidth)
    - #119663 (tests: Normalize `\r\n` to `\n` in some run-make tests)
    - #119681 (coverage: Anonymize line numbers in branch views)
    - #119704 (Fix two variable binding issues in lint let_underscore)
    - #119725 (Add helper for when we want to know if an item has a host param)
    - #119738 (Add `riscv32imafc-esp-espidf` tier 3 target for the ESP32-P4.)
    - #119740 (Remove crossbeam-channel)
  - #119732 (Subtree update of `rust-analyzer`) by lnicola
  - #119760 (Rollup of 7 pull requests) by matthiaskrgr
    - #117744 (Add -Zuse-sync-unwind)
    - #118649 (Make inductive cycles in coherence ambiguous always)
    - #118979 (Use `assert_unsafe_precondition` for `char::from_u32_unchecked`)
    - #119619 (mir-opt and custom target fixes)
    - #119632 (Fix broken build for ESP IDF due to #119026)
    - #119712 (Adding alignment to the cases to test for specific error messages.)
    - #119734 (Miri subtree update)
  - #117703 (Support async recursive calls (as long as they have indirection)) by compiler-errors
  - #118968 (unify query canonicalization mode) by aliemjay
  - #119767 (Rollup of 9 pull requests) by GuillaumeGomez
    - #117556 (Disallow reference to `static mut` and adding `static_mut_ref` lint)
    - #118748 (std: getrandom simplification for freebsd.)
    - #119282 (Rework and improve the unstable documentation of check-cfg)
    - #119527 (don't reexport atomic::ordering via rustc_data_structures, use std import)
    - #119668 (Simplify implementation of MIR promotion)
    - #119699 (Merge dead bb pruning and unreachable bb deduplication.)
    - #119723 (Remove `-Zdont-buffer-diagnostics`.)
    - #119756 (rustdoc-search: reuse individual types in function signatures)
    - #119758 (GNU/Hurd: unconditionally use inline stack probes)
  - #119777 (Rollup of 5 pull requests) by GuillaumeGomez
    - #118241 (Making `User<T>` and `User<[T]>` `Send`)
    - #118645 (chore: Bump compiler_builtins)
    - #118680 (Add support for shell argfiles)
    - #119721 (`~const` trait and projection bounds do not imply their non-const counterparts)
    - #119768 (core: panic: fix broken link)
  - #116846 (A more efficient slice comparison implementation for T: !BytewiseEq) by krtab

• Amongst those, Support async recursive calls (as long as they have indirection) #117703 directly touches recursive async functions