forcing unstable flags during bootstrap does not work

[matthiaskrgr]

RUSTC_BOOTSTRAP=1 RUSTFLAGS="-Zvalidate-mir" ./x.py check

Building bootstrap
error: failed to run `rustc` to learn about target-specific information

Caused by:
  process didn't exit successfully: `/home/matthias/.cargo/bin/sccache /home/matthias/vcs/github/rust/build/x86_64-unknown-linux-gnu/stage0/bin/rustc - --crate-name ___ --print=file-names -Zvalidate-mir -Wrust_2018_idioms -Wunused_lifetimes -Dwarnings --crate-type bin --crate-type rlib --crate-type dylib --crate-type cdylib --crate-type staticlib --crate-type proc-macro --print=sysroot --print=split-debuginfo --print=crate-name --print=cfg` (exit status: 1)
  --- stderr
  error: the option `Z` is only accepted on the nightly compiler

  note: selecting a toolchain with `+toolchain` arguments require a rustup proxy; see <https://rust-lang.github.io/rustup/concepts/index.html>

  help: consider switching to a nightly toolchain: `rustup default nightly`

  note: for more information about Rust's stability policy, see <https://doc.rust-lang.org/book/appendix-07-nightly-rust.html#unstable-features>

failed to run: /home/matthias/vcs/github/rust/build/x86_64-unknown-linux-gnu/stage0/bin/cargo build --manifest-path /home/matthias/vcs/github/rust/src/bootstrap/Cargo.toml
Build completed unsuccessfully in 0:00:00

almost looks like bootstrap intentionally overrides it to 0 again somewhere, otherwise we would just pass through 1...?

[onur-ozkan]

Executed RUSTC_BOOTSTRAP=1 RUSTFLAGS="-Zvalidate-mir" ./x.py check on a fresh clone(with git clean -fdx).

Result: Build completed successfully in 0:03:17

HEAD: 2ffeb46

[matthiaskrgr]

Oh weird. I would expect changing RUSTFLAGS to force a rebuild kinda unconditionally as with cargo build 🤔

[onur-ozkan]

I would expect changing RUSTFLAGS to force a rebuild kinda unconditionally

This is already how it works.

Do you still experience this problem on the latest HEAD?

[matthiaskrgr]

It works now, thank you!🎉