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Don't show the std frames before user code on unwinding.
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When `RUST_BACKTRACE=1`, remove all frames after
`__rust_maybe_catch_panic`. Tested on `main`, threads, tests and
benches. Cleaning of the top of the stacktrace is let to a future PR.

Fixes rust-lang#40201

See rust-lang#41815
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Yamakaky committed May 9, 2017
1 parent f3fc547 commit ca8b754
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Showing 4 changed files with 68 additions and 13 deletions.
7 changes: 4 additions & 3 deletions src/libstd/rt.rs
Original file line number Diff line number Diff line change
Expand Up @@ -29,8 +29,7 @@ pub use panicking::{begin_panic, begin_panic_fmt, update_panic_count};

#[cfg(not(test))]
#[lang = "start"]
fn lang_start(main: *const u8, argc: isize, argv: *const *const u8) -> isize {
use mem;
fn lang_start(main: fn(), argc: isize, argv: *const *const u8) -> isize {
use panic;
use sys;
use sys_common;
Expand All @@ -54,7 +53,9 @@ fn lang_start(main: *const u8, argc: isize, argv: *const *const u8) -> isize {
sys::args::init(argc, argv);

// Let's run some code!
let res = panic::catch_unwind(mem::transmute::<_, fn()>(main));
let res = panic::catch_unwind(|| {
::sys_common::backtrace::__rust_begin_short_backtrace(main)
});
sys_common::cleanup();
res.is_err()
};
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44 changes: 40 additions & 4 deletions src/libstd/sys_common/backtrace.rs
Original file line number Diff line number Diff line change
Expand Up @@ -93,11 +93,47 @@ fn _print(w: &mut Write, format: PrintFormat) -> io::Result<()> {
Ok(())
}

fn filter_frames(_frames: &[Frame],
_format: PrintFormat,
_context: &BacktraceContext) -> (usize, usize)
/// Returns a number of frames to remove at the beginning and at the end of the
/// backtrace, according to the backtrace format.
fn filter_frames(frames: &[Frame],
format: PrintFormat,
context: &BacktraceContext) -> (usize, usize)
{
(0, 0)
if format == PrintFormat::Full {
return (0, 0);
}

let skipped_before = 0;

let skipped_after = frames.len() - frames.iter().position(|frame| {
let mut is_marker = false;
let _ = resolve_symname(*frame, |symname| {
if let Some(mangled_symbol_name) = symname {
// Use grep to find the concerned functions
if mangled_symbol_name.contains("__rust_begin_short_backtrace") {
is_marker = true;
}
}
Ok(())
}, context);
is_marker
}).unwrap_or(frames.len());

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

(skipped_before, skipped_after)
}


/// Fixed frame used to clean the backtrace with `RUST_BACKTRACE=1`.
#[inline(never)]
pub fn __rust_begin_short_backtrace<F, T>(f: F) -> T
where F: FnOnce() -> T, F: Send + 'static, T: Send + 'static
{
f()
}

/// Controls how the backtrace should be formated.
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4 changes: 3 additions & 1 deletion src/libstd/thread/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -358,7 +358,9 @@ impl Builder {
}
unsafe {
thread_info::set(imp::guard::current(), their_thread);
let try_result = panic::catch_unwind(panic::AssertUnwindSafe(f));
let try_result = panic::catch_unwind(panic::AssertUnwindSafe(|| {
::sys_common::backtrace::__rust_begin_short_backtrace(f)
}));
*their_packet.get() = Some(try_result);
}
};
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26 changes: 21 additions & 5 deletions src/libtest/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1314,12 +1314,16 @@ pub fn convert_benchmarks_to_tests(tests: Vec<TestDescAndFn>) -> Vec<TestDescAnd
let testfn = match x.testfn {
DynBenchFn(bench) => {
DynTestFn(Box::new(move |()| {
bench::run_once(|b| bench.run(b))
bench::run_once(|b| {
__rust_begin_short_backtrace(|| bench.run(b))
})
}))
}
StaticBenchFn(benchfn) => {
DynTestFn(Box::new(move |()| {
bench::run_once(|b| benchfn(b))
bench::run_once(|b| {
__rust_begin_short_backtrace(|| benchfn(b))
})
}))
}
f => f,
Expand Down Expand Up @@ -1425,12 +1429,24 @@ pub fn run_test(opts: &TestOpts,
monitor_ch.send((desc, TrMetrics(mm), Vec::new())).unwrap();
return;
}
DynTestFn(f) => run_test_inner(desc, monitor_ch, opts.nocapture, f),
StaticTestFn(f) => run_test_inner(desc, monitor_ch, opts.nocapture,
Box::new(move |()| f())),
DynTestFn(f) => {
let cb = move |()| {
__rust_begin_short_backtrace(|| f.call_box(()))
};
run_test_inner(desc, monitor_ch, opts.nocapture, Box::new(cb))
}
StaticTestFn(f) =>
run_test_inner(desc, monitor_ch, opts.nocapture,
Box::new(move |()| __rust_begin_short_backtrace(f))),
}
}

/// Fixed frame used to clean the backtrace with `RUST_BACKTRACE=1`.
#[inline(never)]
fn __rust_begin_short_backtrace<F: FnOnce()>(f: F) {
f()
}

fn calc_result(desc: &TestDesc, task_result: Result<(), Box<Any + Send>>) -> TestResult {
match (&desc.should_panic, task_result) {
(&ShouldPanic::No, Ok(())) |
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