Compile probe does not take Cargo rustc configuration into account #156
Description
The compile probe just invokes rustc directly, without including relevant cargo configuration. This causes problems in environments where that configuration may change whether or not backtrace is available (or compiles):
cargo new anyhow-issue
cd anyhow-issue
mkdir .cargo
echo '[build]' >> .cargo/config.toml
echo 'rustflags = ["-Zallow-features="]' >> .cargo/config.toml
echo 'anyhow = "1"' >> Cargo.toml
rustup override set nightly
cargo checkproduces
Updating crates.io index
Downloaded anyhow v1.0.41
Downloaded 1 crate (34.6 KB) in 0.68s
Compiling anyhow v1.0.41
error[E0725]: the feature `backtrace` is not in the list of allowed features
--> ~/.cargo/registry/src/github.com-1ecc6299db9ec823/anyhow-1.0.41/src/lib.rs:213:32
|
213 | #![cfg_attr(backtrace, feature(backtrace))]
| ^^^^^^^^^
error[E0658]: use of unstable library feature 'backtrace'
--> ~/.cargo/registry/src/github.com-1ecc6299db9ec823/anyhow-1.0.41/src/backtrace.rs:2:33
|
2 | pub(crate) use std::backtrace::{Backtrace, BacktraceStatus};
| ^^^^^^^^^
|
= note: see issue #53487 <https://github.com/rust-lang/rust/issues/53487> for more information
= help: add `#![feature(backtrace)]` to the crate attributes to enable
...
Taking everything into account is probably too tall of an order, but the Cargo environment variables should get us pretty far. In particular, if set, anyhow should probably take into account these three:
CARGO_BUILD_RUSTCCARGO_BUILD_RUSTC_WRAPPERCARGO_BUILD_RUSTFLAGS
Together, those should encapsulate most of the rustc configuration in cargo.