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Description
I tried this code:
Cargo.toml:
[package]
name = "testcase"
version = "0.1.0"
edition = "2018"
[profile.release]
panic="abort"
[profile.dev]
panic="abort"
[build-dependencies]
cc = "1"
build.rs:
fn main() {
cc::Build::new().file("foo.c").compile("foo");
}foo.c:
#include <stdio.h>
extern void do_rust_panic(const char *msg);
void foo() {
do_rust_panic("foo");
// prevent tail-call optimization so that the frame for foo is always there
printf("foo\n");
}src/main.rs:
use std::ffi::CStr;
use std::os::raw::c_char;
#[no_mangle]
pub unsafe extern "C" fn do_rust_panic(message: *const c_char) {
panic!("{}", CStr::from_ptr(message).to_string_lossy());
}
extern "C" {
fn foo();
}
fn main() {
unsafe {
foo();
}
// prevent tail-call optimization so that the frame for main is always there
println!("Hello, world!");
}I expected to see this happen: the panic backtrace would traverse the ffi code, like it does without panic=abort.
Instead, this happened: the panic backtrace stops at do_rust_panic:
$ RUST_BACKTRACE=1 cargo run --release
Finished release [optimized] target(s) in 0.00s
Running `target/release/testcase`
Hello, world!
thread 'main' panicked at 'foo', src/main.rs:6:5
stack backtrace:
0: rust_begin_unwind
at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/std/src/panicking.rs:515:5
1: std::panicking::begin_panic_fmt
at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/std/src/panicking.rs:457:5
2: do_rust_panic
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Without panic=abort:
$ RUST_BACKTRACE=1 cargo run --release
Finished release [optimized] target(s) in 0.00s
Running `target/release/testcase`
thread 'main' panicked at 'foo', src/main.rs:6:5
stack backtrace:
0: rust_begin_unwind
at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/std/src/panicking.rs:515:5
1: std::panicking::begin_panic_fmt
at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/std/src/panicking.rs:457:5
2: do_rust_panic
3: foo
4: testcase::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Meta
rustc --version --verbose:
rustc 1.54.0 (a178d0322 2021-07-26)
binary: rustc
commit-hash: a178d0322ce20e33eac124758e837cbd80a6f633
commit-date: 2021-07-26
host: x86_64-unknown-linux-gnu
release: 1.54.0
LLVM version: 12.0.1
Also reproducible with nightly:
rustc 1.56.0-nightly (af140757b 2021-08-22)
binary: rustc
commit-hash: af140757b4cb1a60d107c690720311ba8e06e7de
commit-date: 2021-08-22
host: x86_64-unknown-linux-gnu
release: 1.56.0-nightly
LLVM version: 13.0.0
I tried tweaking the FFI build flags, adding combinations of -fno-omit-frame-pointer, -funwind-tables and -g, and none of them changed anything.