rust/src/test/codegen/unwind-and-panic-abort.rs

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rustc: Fill out remaining parts of C-unwind ABI This commit intends to fill out some of the remaining pieces of the C-unwind ABI. This has a number of other changes with it though to move this design space forward a bit. Notably contained within here is: * On `panic=unwind`, the `extern "C"` ABI is now considered as "may unwind". This fixes a longstanding soundness issue where if you `panic!()` in an `extern "C"` function defined in Rust that's actually UB because the LLVM representation for the function has the `nounwind` attribute, but then you unwind. * Whether or not a function unwinds now mainly considers the ABI of the function instead of first checking the panic strategy. This fixes a miscompile of `extern "C-unwind"` with `panic=abort` because that ABI can still unwind. * The aborting stub for non-unwinding ABIs with `panic=unwind` has been reimplemented. Previously this was done as a small tweak during MIR generation, but this has been moved to a separate and dedicated MIR pass. This new pass will, for appropriate functions and function calls, insert a `cleanup` landing pad for any function call that may unwind within a function that is itself not allowed to unwind. Note that this subtly changes some behavior from before where previously on an unwind which was caught-to-abort it would run active destructors in the function, and now it simply immediately aborts the process. * The `#[unwind]` attribute has been removed and all users in tests and such are now using `C-unwind` and `#![feature(c_unwind)]`. I think this is largely the last piece of the RFC to implement. Unfortunately I believe this is still not stabilizable as-is because activating the feature gate changes the behavior of the existing `extern "C"` ABI in a way that has no replacement. My thinking for how to enable this is that we add support for the `C-unwind` ABI on stable Rust first, and then after it hits stable we change the behavior of the `C` ABI. That way anyone straddling stable/beta/nightly can switch to `C-unwind` safely.
2021-06-08 18:23:58 +00:00
// compile-flags: -C panic=abort
#![crate_type = "lib"]
#![feature(c_unwind)]
extern "C-unwind" {
fn bar();
}
// CHECK: Function Attrs:{{.*}}nounwind
// CHECK-NEXT: define{{.*}}void @foo
// CHECK: call void @_ZN4core9panicking15panic_no_unwind
rustc: Fill out remaining parts of C-unwind ABI This commit intends to fill out some of the remaining pieces of the C-unwind ABI. This has a number of other changes with it though to move this design space forward a bit. Notably contained within here is: * On `panic=unwind`, the `extern "C"` ABI is now considered as "may unwind". This fixes a longstanding soundness issue where if you `panic!()` in an `extern "C"` function defined in Rust that's actually UB because the LLVM representation for the function has the `nounwind` attribute, but then you unwind. * Whether or not a function unwinds now mainly considers the ABI of the function instead of first checking the panic strategy. This fixes a miscompile of `extern "C-unwind"` with `panic=abort` because that ABI can still unwind. * The aborting stub for non-unwinding ABIs with `panic=unwind` has been reimplemented. Previously this was done as a small tweak during MIR generation, but this has been moved to a separate and dedicated MIR pass. This new pass will, for appropriate functions and function calls, insert a `cleanup` landing pad for any function call that may unwind within a function that is itself not allowed to unwind. Note that this subtly changes some behavior from before where previously on an unwind which was caught-to-abort it would run active destructors in the function, and now it simply immediately aborts the process. * The `#[unwind]` attribute has been removed and all users in tests and such are now using `C-unwind` and `#![feature(c_unwind)]`. I think this is largely the last piece of the RFC to implement. Unfortunately I believe this is still not stabilizable as-is because activating the feature gate changes the behavior of the existing `extern "C"` ABI in a way that has no replacement. My thinking for how to enable this is that we add support for the `C-unwind` ABI on stable Rust first, and then after it hits stable we change the behavior of the `C` ABI. That way anyone straddling stable/beta/nightly can switch to `C-unwind` safely.
2021-06-08 18:23:58 +00:00
#[no_mangle]
pub unsafe extern "C" fn foo() {
bar();
}