Document any supported environment variables rustc honours

[Earnestly]

I was looking for a collection of environment variables that rustc honours but was unable to find a definitive list. There are a few mentions of variables such as RUSTFLAGS, RUST_THREADS and RUST_BACKTRACE on google but none of them are documented in rustc(1)

Would it be possible to add these to the manual for future reference under an ENVIRONMENT section much like clang and gcc?

[steveklabnik]

Yup, that'd be great.

[steveklabnik]

Lots of these are duplicates, but

steve@computer:~/src/rust$ git grep RUST_  -- src | wc -l
108

[steveklabnik]

This looks like an actual list of all of them right now:

RUST_TEST_TASKS
RUST_LOG 
RUST_BUILD_STAGE
RUST_MAX_CACHED_STACKS
RUST_MIN_STACK
RUST_PATH
DXR_RUST_TEMP_FOLDER
RUST_BACKTRACE
RUST_THREADS
RUST_TEST_STRESS
RUST_TEST_NOCAPTURE
RUST_BENCH
RUST_POISON_ON_FREE
RUST_NEWRT
RUST_TEST_SPAWN_UNICODE

[scott-ainsworth]

FYI: Just added #22334 (Document RUST_TEST_TASKS in the "book") in response to spurious test failures due to parallel text execution.

[steveklabnik]

Full list as of now:

RUST_TEST_TASKS
RUST_TEST_NOCAPTURE
RUST_LOG
RUST_BUILD_STAGE
RUST_URL
RUST_PACKAGE_NAME
RUST_PACKAGE_NAME_AND_TRIPLE
RUST_TARBALL_NAME
RUST_LOCAL_INSTALL_DIR
RUST_LOCAL_INSTALL_SCRIPT
RUST_DOWNLOAD_DIR
RUST_LOCAL_TARBALL
RUST_PATH
RUST_REGION_GRAPH_NODE
RUST_REGION_GRAPH
RUST_TARGET_PATH
RUST_MIN_STACK
RUST_BACKTRACE
RUST_OBJECT
R_RUST_TEMP_FOLDER
RUST_THREADS
RUST_TEST_STRESS
RUST_ANDROID_DUMMY_H
RUST_BENCH
RUST_HOPEFULLY_THIS_DOESNT_EXIST
RUST_NEWRT
RUST_POISON_ON_FREE
RUST_TEST_PROC_SPAWN_UNICODE

[steveklabnik]

(I gusess some of these are not actually env vars)