mirror of https://github.com/rust-lang/rust.git
35 lines
1.3 KiB
Rust
35 lines
1.3 KiB
Rust
//! A test for calling `C-unwind` functions across foreign function boundaries.
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//!
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//! This test triggers a panic in a Rust library that our foreign function invokes. This shows
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//! that we can unwind through the C code in that library, and catch the underlying panic.
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use std::panic::{catch_unwind, AssertUnwindSafe};
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fn main() {
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// Call `add_small_numbers`, passing arguments that will NOT trigger a panic.
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let (a, b) = (9, 1);
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let c = unsafe { add_small_numbers(a, b) };
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assert_eq!(c, 10);
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// Call `add_small_numbers`, passing arguments that will trigger a panic, and catch it.
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let caught_unwind = catch_unwind(AssertUnwindSafe(|| {
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let (a, b) = (10, 1);
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let _c = unsafe { add_small_numbers(a, b) };
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unreachable!("should have unwound instead of returned");
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}));
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// Assert that we did indeed panic, then unwrap and downcast the panic into the sum.
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assert!(caught_unwind.is_err());
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let panic_obj = caught_unwind.unwrap_err();
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let msg = panic_obj.downcast_ref::<String>().unwrap();
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assert_eq!(msg, "11");
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}
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#[link(name = "add", kind = "static")]
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extern "C-unwind" {
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/// An external function, defined in C.
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///
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/// Returns the sum of two numbers, or panics if the sum is greater than 10.
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fn add_small_numbers(a: u32, b: u32) -> u32;
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}
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