This PR modifies src/bootstrap/src/core/config.

If appropriate, please update CONFIG_CHANGE_HISTORY in src/bootstrap/src/utils/change_tracker.rs.

@rustbot ready

r? bootstrap
cc @rust-lang/libs

@rustbot author (currently stage 2 std is copied from stage 1 and this behaviour should change with the beta std change)

Rebased.

Do you still plan to test this PR @jieyouxu? I've rebased it multiple times and it's exhausting a lot, so I would like to hold rebasing again until everyone has finished reviewing and testing.

Yes I'm still testing (but progress has been slow), rebasing is not necessary.

EDIT: trying to get the testing done by today.

Sorry for the wait, but local testing looks good to me (ignore the two problems previously, consider them resolved as they were also discussed in the review thread).

Local manual testing (Round 1)

Known and intentional omissions

• Does not include "base cases" from Round 0.
• Testing conducted on this PR does not exercise download-rustc = "if-unchanged" because this PR obviously by necessity has to modify the compiler/ tree, thereby disqualifying CI rustc "if-unchanged".
• Still missing a lot of configurations.
• Canadian cross scenarios (build != host != target) not tested.
• Local LLVM build not tested.
• macOS host/target not tested.
• windows-{gnu,msvc} as host/target platform not tested.
• ... and a lot more, not tractable to test locally.

Tests

Uniform platform (build == host == target)

Cherry-picked platform: aarch64-unknown-linux-gnu
(This is conducted on one of the AArch64 dev-desktops.)

Check flow

profile = "library" + ./x check library

$ rm -rf build/
$ tee config.toml <<EOF
profile = "library"
EOF

$ ./x check library

$ rm -rf build/

profile = "library" + download-rustc = false + ./x check library

$ rm -rf build/
$ tee config.toml <<EOF
profile = "library"
[rust]
download-rustc = false
EOF

$ ./x check library

$ rm -rf build/

profile = "library" + ./x check library --stage=0

$ rm -rf build/
$ tee config.toml <<EOF
profile = "library"
EOF

$ ./x check library --stage=0

$ rm -rf build/

profile = "library" + ./x check library --stage=1

$ rm -rf build/
$ tee config.toml <<EOF
profile = "library"
EOF

$ ./x check library --stage=1

$ rm -rf build/

profile = "library" + ./x check library --stage=2

$ rm -rf build/
$ tee config.toml <<EOF
profile = "library"
EOF

$ ./x check library --stage=2

$ rm -rf build/

profile = "library" + ./x check std

$ rm -rf build/
$ tee config.toml <<EOF
profile = "library"
EOF

$ ./x check std

$ rm -rf build/

profile = "library" + ./x check core

$ rm -rf build/
$ tee config.toml <<EOF
profile = "library"
EOF

$ ./x check core

$ rm -rf build/

profile = "library" + ./x check alloc

$ rm -rf build/
$ tee config.toml <<EOF
profile = "library"
EOF

$ ./x check alloc

$ rm -rf build/

Build flow

profile = "compiler" + ./x build library --stage=0

$ rm -rf build/
$ tee config.toml <<EOF
profile = "compiler"
EOF

$ ./x build library --stage=0

$ rm -rf build/

profile = "compiler" + ./x build library --stage=1

$ rm -rf build/
$ tee config.toml <<EOF
profile = "compiler"
EOF

$ ./x build library --stage=1

$ rm -rf build/

profile = "compiler" + ./x build library --stage=2

$ rm -rf build/
$ tee config.toml <<EOF
profile = "compiler"
EOF

$ ./x build library --stage=2

$ rm -rf build/

Test flow

COMPILETEST_FORCE_STAGE0=1 ./x test run-make --stage=0

$ rm -rf build/
$ tee config.toml <<EOF
profile = "compiler"
EOF

$ COMPILETEST_FORCE_STAGE0=1 ./x test run-make --stage=0

$ rm -rf build/

profile = "compiler" + ./x test --stage=2

$ rm -rf build/
$ tee config.toml <<EOF
profile = "compiler"
EOF

$ ./x test --stage=2 --skip=tests/debuginfo

$ rm -rf build/

Build cache invalidation and spurious rebuilds

profile = "compiler" + ./x test mir-opt + ./x test mir-opt

$ rm -rf build/
$ tee config.toml <<EOF
profile = "compiler"
EOF

$ `./x test mir-opt`

$ rm -rf build/

--keep-stage-std

profile = "compiler" + ./x build library --stage=1 + ./x build library --keep-stage-std=1

$ rm -rf build/
$ tee config.toml <<EOF
profile = "compiler"
EOF

$ ./x build library --stage=1
$ echo "// meow" >> compiler/rustc_driver/src/lib.rs
$ ./x build library --keep-stage-std=1

$ rm -rf build/
$ git checkout -- .

Cross-compile (build == host)

Cherry-picked sample:

• Build platform: x86_64-unknown-linux-gnu
• Host platform: x86_64-unknown-linux-gnu
• Target platform: wasm32-unknown-unknown

$ rm -rf build/
$ tee config.toml <<EOF
profile = "compiler"

[build]
target = [
  "wasm32-unknown-unknown",
]

[target."wasm32-unknown-unknown"]
wasi-root = "../wasi-sdk-24.0-x86_64-linux/"
EOF

$ ./x build library

$ rm -rf build/

I think the merge CI will run the most comprehensive and detailed tests on this.

Many things are not tested by CI, e.g. AFAIK we still do not test whether things like Miri work properly in stage 1 (might be stage 0 after this PR?). CI typically only tests stage 2, involving at least 2 compiler builds, which does not match local development builds.

(I will also run a bunch of try builds here to check that they work and how long they take).

@bors try @rust-timer queue

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

⌛ Trying commit 664d864 with merge 5f2f74fb8dda1fcd5e50db388713213585ff11c3...