rust/tests/ui/panic-runtime/unwind-tables-target-required.rs

// Tests that the compiler errors if the user tries to turn off unwind tables
// when they are required.
//
// only-x86_64-windows-msvc
// compile-flags: -C force-unwind-tables=no
//
// error-pattern: target requires unwind tables, they cannot be disabled with `-C force-unwind-tables=no`.

pub fn main() {
}
Add Option to Force Unwind Tables When panic != unwind, `nounwind` is added to all functions for a target. This can cause issues when a panic happens with RUST_BACKTRACE=1, as there needs to be a way to reconstruct the backtrace. There are three possible sources of this information: forcing frame pointers (for which an option exists already), debug info (for which an option exists), or unwind tables. Especially for embedded devices, forcing frame pointers can have code size overheads (RISC-V sees ~10% overheads, ARM sees ~2-3% overheads). In code, it can be the case that debug info is not kept, so it is useful to provide this third option, unwind tables, that users can use to reconstruct the call stack. Reconstructing this stack is harder than with frame pointers, but it is still possible. This commit adds a compiler option which allows a user to force the addition of unwind tables. Unwind tables cannot be disabled on targets that require them for correctness, or when using `-C panic=unwind`. 2020-05-04 11:08:35 +00:00			`// Tests that the compiler errors if the user tries to turn off unwind tables`
			`// when they are required.`
			`//`
			`// only-x86_64-windows-msvc`
			`// compile-flags: -C force-unwind-tables=no`
			`//`
			// error-pattern: target requires unwind tables, they cannot be disabled with `-C force-unwind-tables=no`.

			`pub fn main() {`
			`}`