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Rename to RUSTC_LOG #315

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May 3, 2019
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Rename to RUSTC_LOG #315

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18 changes: 9 additions & 9 deletions src/compiler-debugging.md
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Original file line number Diff line number Diff line change
Expand Up @@ -149,7 +149,7 @@ $ # Cool, now I have a backtrace for the error
These crates are used in compiler for logging:

* [log]
* [env-logger]: check the link to see the full `RUST_LOG` syntax
* [env-logger]: check the link to see the full `RUSTC_LOG` syntax

[log]: https://docs.rs/log/0.4.6/log/index.html
[env-logger]: https://docs.rs/env_logger/0.4.3/env_logger/
Expand All @@ -159,9 +159,9 @@ at many points. These are very useful to at least narrow down the location of
a bug if not to find it entirely, or just to orient yourself as to why the
compiler is doing a particular thing.

To see the logs, you need to set the `RUST_LOG` environment variable to
To see the logs, you need to set the `RUSTC_LOG` environment variable to
your log filter, e.g. to get the logs for a specific module, you can run the
compiler as `RUST_LOG=module::path rustc my-file.rs`. All `debug!` output will
compiler as `RUSTC_LOG=module::path rustc my-file.rs`. All `debug!` output will
then appear in standard error.

**Note that unless you use a very strict filter, the logger will emit a lot of
Expand All @@ -174,16 +174,16 @@ So to put it together.
```bash
# This puts the output of all debug calls in `librustc/traits` into
# standard error, which might fill your console backscroll.
$ RUST_LOG=rustc::traits rustc +local my-file.rs
$ RUSTC_LOG=rustc::traits rustc +local my-file.rs

# This puts the output of all debug calls in `librustc/traits` in
# `traits-log`, so you can then see it with a text editor.
$ RUST_LOG=rustc::traits rustc +local my-file.rs 2>traits-log
$ RUSTC_LOG=rustc::traits rustc +local my-file.rs 2>traits-log

# Not recommended. This will show the output of all `debug!` calls
# in the Rust compiler, and there are a *lot* of them, so it will be
# hard to find anything.
$ RUST_LOG=debug rustc +local my-file.rs 2>all-log
$ RUSTC_LOG=debug rustc +local my-file.rs 2>all-log

# This will show the output of all `info!` calls in `rustc_trans`.
#
Expand All @@ -192,7 +192,7 @@ $ RUST_LOG=debug rustc +local my-file.rs 2>all-log
# which function triggers an LLVM assertion, and this is an `info!`
# log rather than a `debug!` log so it will work on the official
# compilers.
$ RUST_LOG=rustc_trans=info rustc +local my-file.rs
$ RUSTC_LOG=rustc_trans=info rustc +local my-file.rs
```

### How to keep or remove `debug!` and `trace!` calls from the resulting binary
Expand All @@ -201,7 +201,7 @@ While calls to `error!`, `warn!` and `info!` are included in every build of the
calls to `debug!` and `trace!` are only included in the program if
`debug-assertions=yes` is turned on in config.toml (it is
turned off by default), so if you don't see `DEBUG` logs, especially
if you run the compiler with `RUST_LOG=rustc rustc some.rs` and only see
if you run the compiler with `RUSTC_LOG=rustc rustc some.rs` and only see
`INFO` logs, make sure that `debug-assertions=yes` is turned on in your
config.toml.

Expand Down Expand Up @@ -230,7 +230,7 @@ If in the module `rustc::foo` you have a statement
debug!("{:?}", random_operation(tcx));
```

Then if someone runs a debug `rustc` with `RUST_LOG=rustc::bar`, then
Then if someone runs a debug `rustc` with `RUSTC_LOG=rustc::bar`, then
`random_operation()` will run.

This means that you should not put anything too expensive or likely to crash
Expand Down