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Prevent double panic when handling incremental fingerprint mismatch

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When an incremental fingerprint mismatch occurs, we debug-print
our `DepNode` and query result. Unfortunately, the debug printing
process may cause us to run additional queries, which can result
in a re-entrant fingerprint mismatch error.

To avoid a double panic, this commit adds a thread-local variable
to detect re-entrant calls.
This commit is contained in:
Aaron Hill 2021-08-12 15:11:21 -05:00
parent 4498e300e4
commit 77b02eed7b
No known key found for this signature in database
GPG Key ID: B4087E510E98B164
2 changed files with 28 additions and 6 deletions
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1
compiler/rustc_query_system/src/lib.rs
View File

@ -3,6 +3,7 @@
#![feature(hash_raw_entry)]
#![feature(iter_zip)]
#![feature(min_specialization)]
#![feature(thread_local_const_init)]
#[macro_use]
extern crate tracing;

33
compiler/rustc_query_system/src/query/plumbing.rs
View File

@ -20,6 +20,7 @@ use rustc_data_structures::thin_vec::ThinVec;
use rustc_errors::DiagnosticBuilder;
use rustc_errors::{Diagnostic, FatalError};
use rustc_span::{Span, DUMMY_SP};
use std::cell::Cell;
use std::collections::hash_map::Entry;
use std::fmt::Debug;
use std::hash::{Hash, Hasher};
@ -618,12 +619,32 @@ fn incremental_verify_ich<CTX, K, V: Debug>(
} else {
"`cargo clean`".to_string()
};
tcx.sess().struct_err(&format!("internal compiler error: encountered incremental compilation error with {:?}", dep_node))
.help(&format!("This is a known issue with the compiler. Run {} to allow your project to compile", run_cmd))
.note(&"Please follow the instructions below to create a bug report with the provided information")
.note(&"See <https://github.com/rust-lang/rust/issues/84970> for more information")
.emit();
panic!("Found unstable fingerprints for {:?}: {:?}", dep_node, result);
// When we emit an error message and panic, we try to debug-print the `DepNode`
// and query result. Unforunately, this can cause us to run additional queries,
// which may result in another fingerprint mismatch while we're in the middle
// of processing this one. To avoid a double-panic (which kills the process
// before we can print out the query static), we print out a terse
// but 'safe' message if we detect a re-entrant call to this method.
thread_local! {
static INSIDE_VERIFY_PANIC: Cell<bool> = const { Cell::new(false) };
};
let old_in_panic = INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.replace(true));
if old_in_panic {
tcx.sess().struct_err("internal compiler error: re-entrant incremental verify failure, suppressing message")
.emit();
} else {
tcx.sess().struct_err(&format!("internal compiler error: encountered incremental compilation error with {:?}", dep_node))
.help(&format!("This is a known issue with the compiler. Run {} to allow your project to compile", run_cmd))
.note(&"Please follow the instructions below to create a bug report with the provided information")
.note(&"See <https://github.com/rust-lang/rust/issues/84970> for more information")
.emit();
panic!("Found unstable fingerprints for {:?}: {:?}", dep_node, result);
}
INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.set(old_in_panic));
}
}