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Ignore more frames on backtrace unwinding. #40264

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65 changes: 50 additions & 15 deletions src/libstd/sys_common/backtrace.rs
Original file line number Diff line number Diff line change
Expand Up @@ -107,47 +107,66 @@ fn filter_frames(frames: &[Frame],
"_ZN3std3sys3imp9backtrace",
"ZN3std3sys3imp9backtrace",
"std::sys::imp::backtrace",

"_ZN3std10sys_common9backtrace",
"ZN3std10sys_common9backtrace",
"std::sys_common::backtrace",

"_ZN3std9panicking",
"ZN3std9panicking",
"std::panicking",

"_ZN4core9panicking",
"ZN4core9panicking",
"core::panicking",

"_ZN4core6result13unwrap_failed",
"ZN4core6result13unwrap_failed",
"core::result::unwrap_failed",

"rust_begin_unwind",
"_ZN4drop",
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Er was this added in the previous PR? This definitely seems like something that we shouldn't be dropping, this is just a normal function?

"mingw_set_invalid_parameter_handler",
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This and drop above should be removed

];
static BAD_PREFIXES_BOTTOM: &'static [&'static str] = &[
"_ZN4core9panicking",
"ZN4core9panicking",
"core::panicking",

"_ZN3std9panicking",
"ZN3std9panicking",
"std::panicking",

"_ZN3std5panic",
"ZN3std5panic",
"std::panic",
"_ZN4core9panicking",
"ZN4core9panicking",
"core::panicking",
"_ZN3std2rt10lang_start",
"ZN3std2rt10lang_start",
"std::rt::lang_start",
"panic_unwind::__rust_maybe_catch_panic",
"__rust_maybe_catch_panic",
"_rust_maybe_catch_panic",
"__libc_start_main",

"__rust_try",
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I don't think that we want this to be the bottom of a frame, this is just one panic::catch_unwind and there could be many on the stack.

"_start",
"main",
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__libc_start_main, _start and main appear at the bottom of the stack and need to be filtered away.
They are removed from the list in this PR, but they may be required again if the "filtering point" is moved from rust_maybe_catch_panic below (e.g. to lang_start), I don't remember exactly what's their relative order.

"BaseThreadInitThunk",
"RtlInitializeExceptionChain",
"__scrt_common_main_seh",
"_ZN4drop",
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IIRC, _ZN4drop were some kind of corrupted misinterpreted frames on 32-bit mingw (similar to mingw_set_invalid_parameter_handler). Not sure how reproducible they are on executables other than run-pass/bactrace.rs test.

"mingw_set_invalid_parameter_handler",

"_ZN4core3ops6FnOnce9call_once",
"ZN4core3ops6FnOnce9call_once",
"core::ops::FnOnce::call_once",
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Like above, these could be any rust function, so we shouldn't prune these

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I fail to find an example where this frame would be at the beginning of the frame and you would not want to remove it. There will always be the main, or a function if it's a library.


// tests
"_ZN91_$LT$std..panic..AssertUnwindSafe$LT$F$GT$$u20$as$u20$core..ops..FnOnce\
$LT$$LP$$RP$$GT$$GT$9call_once",
"ZN91_$LT$std..panic..AssertUnwindSafe$LT$F$GT$$u20$as$u20$core..ops..FnOnce\
$LT$$LP$$RP$$GT$$GT$9call_once",
"<std::panic::AssertUnwindSafe<F> as core::ops::FnOnce<()>>::call_once",
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I don't think that these are correct to have because this is just the beginning of a catch_unwind, right?

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So? It's std stuff, we want to remove it.


"_ZN4test8run_test",
"ZN4test8run_test",
"test::run_test",

"_ZN42_$LT$F$u20$as$u20$test..FnBox$LT$T$GT$$GT$8call_box",
"ZN42_$LT$F$u20$as$u20$test..FnBox$LT$T$GT$$GT$8call_box",
"<F as test::FnBox<T>>::call_box",
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These can happen at any time, right? Not just during tests?

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Not sure, but it was fine during my tests.


];

let is_good_frame = |frame: Frame, bad_prefixes: &[&str]| {
Expand All @@ -164,11 +183,27 @@ fn filter_frames(frames: &[Frame],
let skipped_before = frames.iter().position(|frame| {
is_good_frame(*frame, BAD_PREFIXES_TOP)
}).unwrap_or(frames.len());
let skipped_after = frames[skipped_before..].iter().rev().position(|frame| {
let idx_catch_panic = skipped_before + frames[skipped_before..].iter().rposition(|frame| {
let mut is_rmcp = false;
let _ = resolve_symname(*frame, |symname| {
if let Some(mangled_symbol_name) = symname {
if mangled_symbol_name == "__rust_maybe_catch_panic" {
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This needs to be mangled_symbol_name.contains("rust_maybe_catch_panic") (regardless of other concerns) because the symbol can be named panic_unwind::__rust_maybe_catch_panic or _rust_maybe_catch_panic (on Windows).

is_rmcp = true;
}
}
Ok(())
}, context);
is_rmcp
}).unwrap_or(0);
let skipped_after =
frames.len() - idx_catch_panic
+ frames[skipped_before..idx_catch_panic].iter()
.rev()
.position(|frame| {
is_good_frame(*frame, BAD_PREFIXES_BOTTOM)
}).unwrap_or(frames.len() - skipped_before);
}).unwrap_or(0);

if skipped_before + skipped_after == frames.len() {
if skipped_before + skipped_after >= frames.len() {
// Avoid showing completely empty backtraces
return (0, 0);
}
Expand Down