fe66eaa67a
The linux backtrace unwinder relies on unwind tables to work properly, and generating and printing a backtrace is done by for example the default panic hook. Begin emitting unwind tables by default again with `-C panic=abort` (see history below) so that backtraces work. History ======= Backtraces with `-C panic=abort` used to work in Rust 1.22 but broke in Rust 1.23, because in 1.23 we stopped emitting unwind tables with `-C panic=abort` (see24cc38e3b0). In 1.45 (seecda994633e) a workaround in the form of `-C force-unwind-tables=yes` was added. `-C panic=abort` was added in [Rust 1.10](https://blog.rust-lang.org/2016/07/07/Rust-1.10/#what-s-in-1-10-stable) and the motivation was binary size and compile time. But given how confusing that behavior has turned out to be, it is better to make binary size optimization opt-in with `-C force-unwind-tables=no` rather than default since the current default breaks backtraces. Besides, if binary size is a primary concern, there are many other tricks that can be used that has a higher impact.
58 lines
2.0 KiB
Rust
58 lines
2.0 KiB
Rust
//! Test that with `-C panic=abort` the backtrace is not cut off by default
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//! (i.e. without using `-C force-unwind-tables=yes`) by ensuring that our own
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//! functions are in the backtrace. If we just check one function it might be
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//! the last function, so make sure the backtrace can continue by checking for
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//! two functions. Regression test for
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//! <https://github.com/rust-lang/rust/issues/81902>.
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//@ run-pass
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//@ needs-subprocess
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// We want to test if unwind tables are emitted by default. We must make sure
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// to disable debuginfo to test that, because enabling debuginfo also means that
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// unwind tables are emitted, which prevents us from testing what we want.
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// We also need to set opt-level=0 to avoid optimizing away our functions.
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//@ compile-flags: -C panic=abort -C opt-level=0 -C debuginfo=0
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//@ no-prefer-dynamic
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//@ ignore-apple
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//@ ignore-arm-unknown-linux-gnueabihf FIXME(#146996) Try removing this once #146996 has been fixed.
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//@ ignore-msvc Backtraces on Windows requires debuginfo which we can't use here
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static FN_1: &str = "this_function_must_be_in_the_backtrace";
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fn this_function_must_be_in_the_backtrace() {
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and_this_function_too();
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}
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static FN_2: &str = "and_this_function_too";
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fn and_this_function_too() {
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panic!("generate panic backtrace");
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}
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fn run_test() {
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let output = std::process::Command::new(std::env::current_exe().unwrap())
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.arg("whatever")
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.env("RUST_BACKTRACE", "full")
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.output()
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.unwrap();
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let backtrace = std::str::from_utf8(&output.stderr).unwrap();
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fn assert(function_name: &str, backtrace: &str) {
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assert!(
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backtrace.contains(function_name),
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"ERROR: no `{}` in stderr! actual stderr: {}",
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function_name,
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backtrace
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);
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}
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assert(FN_1, backtrace);
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assert(FN_2, backtrace);
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}
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fn main() {
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let args: Vec<String> = std::env::args().collect();
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if args.len() == 1 {
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run_test();
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} else {
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this_function_must_be_in_the_backtrace();
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}
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}
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