rust/tests/ui/panics/panic-short-backtrace-windows-x86_64.run.stderr

thread 'main' panicked at 'd was called', $DIR/panic-short-backtrace-windows-x86_64.rs:48:5
stack backtrace:
   0: std::panicking::begin_panic
   1: d
   2: c
   3: b
   4: a
   5: some Rust fn
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
[backtraces]: look for the `begin` symbol only after seeing `end` On `x86_64-pc-windows-msvc`, we often get backtraces which look like this: ``` 10: 0x7ff77e0e9be5 - std::panicking::rust_panic_with_hook 11: 0x7ff77e0e11b4 - std::sys_common::backtrace::__rust_begin_short_backtrace::h5769736bdb11136c 12: 0x7ff77e0e116f - std::sys_common::backtrace::__rust_end_short_backtrace::h61c7ecb1b55338ae 13: 0x7ff77e0f89dd - std::panicking::begin_panic::h8e60ef9f82a41805 14: 0x7ff77e0e108c - d 15: 0x7ff77e0e1069 - c 16: 0x7ff77e0e1059 - b 17: 0x7ff77e0e1049 - a 18: 0x7ff77e0e1039 - core::ptr::drop_in_place<std::rt::lang_start<()>::{{closure}}>::h1bfcd14d5e15ba81 19: 0x7ff77e0e1186 - std::sys_common::backtrace::__rust_begin_short_backtrace::h5769736bdb11136c 20: 0x7ff77e0e100c - std::rt::lang_start::{{closure}}::ha054184bbf9921e3 ``` Notice that `__rust_begin_short_backtrace` appears on frame 11 before `__rust_end_short_backtrace` on frame 12. This is because in typical release binaries without debug symbols, dbghelp.dll, which we use to walk and symbolize the stack, does not know where CGU internal functions start or end and so the closure invoked by `__rust_end_short_backtrace` is incorrectly described as `__rust_begin_short_backtrace` because it happens to be near that symbol. While that can obviously change, this has been happening quite consistently since #75048. Since this is a very small change to the std and the change makes sense by itself, I think this is worth doing. This doesn't completely resolve the situation for release binaries on Windows, since without debug symbols, the stack printed can still show incorrect symbol names (this is why the test uses `#[no_mangle]`) but it does slightly improve the situation in that you see the same backtrace you would see with `RUST_BACKTRACE=full` or in a debugger (without the uninteresting bits at the top and bottom). 2021-07-29 17:06:37 +00:00			`thread 'main' panicked at 'd was called', $DIR/panic-short-backtrace-windows-x86_64.rs:48:5`
Add regression test 2021-07-28 15:40:53 +00:00			`stack backtrace:`
[backtraces]: look for the `begin` symbol only after seeing `end` On `x86_64-pc-windows-msvc`, we often get backtraces which look like this: ``` 10: 0x7ff77e0e9be5 - std::panicking::rust_panic_with_hook 11: 0x7ff77e0e11b4 - std::sys_common::backtrace::__rust_begin_short_backtrace::h5769736bdb11136c 12: 0x7ff77e0e116f - std::sys_common::backtrace::__rust_end_short_backtrace::h61c7ecb1b55338ae 13: 0x7ff77e0f89dd - std::panicking::begin_panic::h8e60ef9f82a41805 14: 0x7ff77e0e108c - d 15: 0x7ff77e0e1069 - c 16: 0x7ff77e0e1059 - b 17: 0x7ff77e0e1049 - a 18: 0x7ff77e0e1039 - core::ptr::drop_in_place<std::rt::lang_start<()>::{{closure}}>::h1bfcd14d5e15ba81 19: 0x7ff77e0e1186 - std::sys_common::backtrace::__rust_begin_short_backtrace::h5769736bdb11136c 20: 0x7ff77e0e100c - std::rt::lang_start::{{closure}}::ha054184bbf9921e3 ``` Notice that `__rust_begin_short_backtrace` appears on frame 11 before `__rust_end_short_backtrace` on frame 12. This is because in typical release binaries without debug symbols, dbghelp.dll, which we use to walk and symbolize the stack, does not know where CGU internal functions start or end and so the closure invoked by `__rust_end_short_backtrace` is incorrectly described as `__rust_begin_short_backtrace` because it happens to be near that symbol. While that can obviously change, this has been happening quite consistently since #75048. Since this is a very small change to the std and the change makes sense by itself, I think this is worth doing. This doesn't completely resolve the situation for release binaries on Windows, since without debug symbols, the stack printed can still show incorrect symbol names (this is why the test uses `#[no_mangle]`) but it does slightly improve the situation in that you see the same backtrace you would see with `RUST_BACKTRACE=full` or in a debugger (without the uninteresting bits at the top and bottom). 2021-07-29 17:06:37 +00:00			`0: std::panicking::begin_panic`
			`1: d`
			`2: c`
			`3: b`
			`4: a`
			`5: some Rust fn`
Add regression test 2021-07-28 15:40:53 +00:00			note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.