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Rollup merge of #64799 - Aaron1011:fix/double-panic, r=Mark-Simulacrum

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Fix double panic when printing query stack during an ICE

On the latest nightly, any call to `bug` or `span_bug` will result in two panics - the first one as a normal result of calling `bug` / `span_bug`, and the second as a result of trying to print the query stack from the panic handler. This is caused by the query-printing code attempting to acquire a lock on `HandlerInnder`, which is still being held by `bug`.

This PR moves the actual panic out of `HandlerInner`, into `Handler`. This allows us to release the lock on `HandlerInner` before triggering the panic, ensuring that the panic handler will be able to acquire the lock if necessary.
This commit is contained in:
Mazdak Farrokhzad 2019-09-29 04:36:01 +02:00 committed by GitHub
commit b30d9beafb
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2 changed files with 7 additions and 3 deletions
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8
src/librustc/ty/query/plumbing.rs
View file

@ -15,6 +15,7 @@ use errors::DiagnosticBuilder;
use errors::Level;
use errors::Diagnostic;
use errors::FatalError;
use errors::Handler;
use rustc_data_structures::fx::{FxHashMap};
use rustc_data_structures::sync::{Lrc, Lock};
use rustc_data_structures::sharded::Sharded;
@ -321,9 +322,12 @@ impl<'tcx> TyCtxt<'tcx> {
})
}
pub fn try_print_query_stack() {
pub fn try_print_query_stack(handler: &Handler) {
eprintln!("query stack during panic:");
// Be careful reyling on global state here: this code is called from
// a panic hook, which means that the global `Handler` may be in a weird
// state if it was responsible for triggering the panic.
tls::with_context_opt(|icx| {
if let Some(icx) = icx {
let mut current_query = icx.query.clone();
@ -336,7 +340,7 @@ impl<'tcx> TyCtxt<'tcx> {
query.info.query.name(),
query.info.query.describe(icx.tcx)));
diag.span = icx.tcx.sess.source_map().def_span(query.info.span).into();
icx.tcx.sess.diagnostic().force_print_diagnostic(diag);
handler.force_print_diagnostic(diag);
current_query = query.parent.clone();
i += 1;

2
src/librustc_driver/lib.rs
View file

@ -1231,7 +1231,7 @@ pub fn report_ice(info: &panic::PanicInfo<'_>, bug_report_url: &str) {
let backtrace = env::var_os("RUST_BACKTRACE").map(|x| &x != "0").unwrap_or(false);
if backtrace {
TyCtxt::try_print_query_stack();
TyCtxt::try_print_query_stack(&handler);
}
#[cfg(windows)]