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Make SIGSEGV handler emit nicer backtraces #113565

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Merged
merged 3 commits into from
Aug 30, 2023
Merged

Make SIGSEGV handler emit nicer backtraces #113565

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4fa00c2
Explain SIGSEGV backtrace handler
workingjubilee Jul 11, 2023
1e65b5b
Add recursion detection to signal-safe backtrace
workingjubilee Jul 13, 2023
3dee977
Clarify arbitrary constants
workingjubilee Jul 15, 2023
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5 changes: 3 additions & 2 deletions compiler/rustc_driver_impl/src/signal_handler.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -87,14 +87,15 @@ extern "C" fn print_stack_trace(_: libc::c_int) {
raw_errln!("");
written += rem.len() + 1;

if cyclic || stack.len() == 256 {
let random_depth = || 8 * 16; // chosen by random diceroll (2d20)
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@pnkfelix pnkfelix Aug 30, 2023

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(... I don't understand why this is a closure versus just a let-bound usize.)

if cyclic || stack.len() > random_depth() {
// technically speculation, but assert it with confidence anyway.
// rustc only arrived in this signal handler because bad things happened
// and this message is for explaining it's not the programmer's fault
raw_errln!("note: rustc unexpectedly overflowed its stack! this is a bug");
written += 1;
}
if stack.len() == 256 {
if stack.len() == MAX_FRAMES {
raw_errln!("note: maximum backtrace depth reached, frames may have been lost");
written += 1;
}
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