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Rollup merge of #75143 - oli-obk:tracing, r=RalfJung

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Use `tracing` spans to trace the entire MIR interp stack

r? @RalfJung

While being very verbose, this allows really good tracking of what's going on. While I considered schemes like the previous indenter that we had (which we could get by using the `tracing-tree` crate), this will break down horribly with things like multithreaded rustc. Instead, we can now use `RUSTC_LOG` to restrict the things being traced. You could specify a filter in a way that only shows the logging of a specific frame.

![screenshot of command line output of the new formatting](https://user-images.githubusercontent.com/332036/89291343-aa40de00-d65a-11ea-9f6c-ea06c1806327.png)

If we lower the span's level to `debug`, then in `info` level logging we'd not see the frames, but in `debug` level we would see them. The filtering rules in `tracing` are super powerful, but  I'm not sure if we can specify a filter so we do see `debug` level events, but *not* the `frame` spans. The documentation at https://docs.rs/tracing-subscriber/0.2.10/tracing_subscriber/struct.EnvFilter.html makes me think that we can only turn on things, not turn off things at a more precise level.

cc @hawkw
This commit is contained in:
Yuki Okushi 2020-10-04 11:44:49 +09:00 • committed by GitHub
commit 6e25418474
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6 changed files with 74 additions and 40 deletions
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18
compiler/rustc_driver/src/lib.rs
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@ -1251,11 +1251,21 @@ pub fn init_env_logger(env: &str) {
Ok(s) if s.is_empty() => return,
Ok(_) => {}
}
let builder = tracing_subscriber::FmtSubscriber::builder();
let filter = tracing_subscriber::EnvFilter::from_env(env);
let layer = tracing_tree::HierarchicalLayer::default()
.with_indent_lines(true)
.with_ansi(true)
.with_targets(true)
.with_thread_ids(true)
.with_thread_names(true)
.with_wraparound(10)
.with_verbose_exit(true)
.with_verbose_entry(true)
.with_indent_amount(2);
let builder = builder.with_env_filter(tracing_subscriber::EnvFilter::from_env(env));
builder.init()
use tracing_subscriber::layer::SubscriberExt;
let subscriber = tracing_subscriber::Registry::default().with(filter).with(layer);
tracing::subscriber::set_global_default(subscriber).unwrap();
}
pub fn main() -> ! {