From 49fd71bea7bd3d8d11818503ca048227ffa1e758 Mon Sep 17 00:00:00 2001 From: Wesley Wiser Date: Thu, 22 Mar 2018 22:25:57 -0400 Subject: [PATCH] [incremental] Don't panic if decoding the cache fails If the cached data can't be loaded from disk, just issue a warning to the user so they know why compilation is taking longer than usual but don't fail the entire compilation since we can recover by ignorning the on disk cache. In the same way, if the disk cache can't be deserialized (because it has been corrupted for some reason), report the issue as a warning and continue without failing the compilation. `Decodable::decode()` tends to panic with various errors like "entered unreachable code" or "index out of range" if the input data is corrupted. Work around this by catching panics from the `decode()` calls when joining the thread and continuing without the cached data. Fixes #48847 --- src/librustc_driver/driver.rs | 4 +++- src/librustc_incremental/lib.rs | 1 + src/librustc_incremental/persist/load.rs | 3 ++- src/librustc_incremental/persist/mod.rs | 1 + 4 files changed, 7 insertions(+), 2 deletions(-) diff --git a/src/librustc_driver/driver.rs b/src/librustc_driver/driver.rs index a3115544f30b9..c6ebc99268057 100644 --- a/src/librustc_driver/driver.rs +++ b/src/librustc_driver/driver.rs @@ -901,7 +901,9 @@ pub fn phase_2_configure_and_expand_inner<'a, F>(sess: &'a Session, Some(future) => { let prev_graph = time(sess, "blocked while dep-graph loading finishes", || { future.open() - .expect("Could not join with background dep_graph thread") + .unwrap_or_else(|e| rustc_incremental::LoadResult::Error { + message: format!("could not decode incremental cache: {:?}", e) + }) .open(sess) }); DepGraph::new(prev_graph) diff --git a/src/librustc_incremental/lib.rs b/src/librustc_incremental/lib.rs index d7ccf9d5562e6..4b524287ca1c7 100644 --- a/src/librustc_incremental/lib.rs +++ b/src/librustc_incremental/lib.rs @@ -39,6 +39,7 @@ pub use assert_dep_graph::assert_dep_graph; pub use persist::dep_graph_tcx_init; pub use persist::load_dep_graph; pub use persist::load_query_result_cache; +pub use persist::LoadResult; pub use persist::save_dep_graph; pub use persist::save_trans_partition; pub use persist::save_work_products; diff --git a/src/librustc_incremental/persist/load.rs b/src/librustc_incremental/persist/load.rs index 38468e29427b0..44d6e532f79bb 100644 --- a/src/librustc_incremental/persist/load.rs +++ b/src/librustc_incremental/persist/load.rs @@ -89,7 +89,8 @@ impl LoadResult { pub fn open(self, sess: &Session) -> PreviousDepGraph { match self { LoadResult::Error { message } => { - sess.fatal(&message) /* never returns */ + sess.warn(&message); + PreviousDepGraph::new(SerializedDepGraph::new()) }, LoadResult::DataOutOfDate => { if let Err(err) = delete_all_session_dir_contents(sess) { diff --git a/src/librustc_incremental/persist/mod.rs b/src/librustc_incremental/persist/mod.rs index 2f864aaefba89..755a550b5bca3 100644 --- a/src/librustc_incremental/persist/mod.rs +++ b/src/librustc_incremental/persist/mod.rs @@ -27,6 +27,7 @@ pub use self::fs::prepare_session_directory; pub use self::load::dep_graph_tcx_init; pub use self::load::load_dep_graph; pub use self::load::load_query_result_cache; +pub use self::load::LoadResult; pub use self::save::save_dep_graph; pub use self::save::save_work_products; pub use self::work_product::save_trans_partition;