Equivalent of CC_ENABLE_DEBUG_OUTPUT=1 cargo build -vv

[mlowicki]

Hi there!

If crate's build script uses cc crate for compiling then CC_ENABLE_DEBUG_OUTPUT=1 cargo build -vv gives very details output of all of the commands run with flags so it's easy to see flags passed to the compiler. Is the anything similar for project using Bazel instead of Cargo?

To the place where https://bazelbuild.github.io/rules_rust/cargo.html#cargo_build_script is used I've added :

    build_script_env = {
        "CC_ENABLE_DEBUG_OUTPUT": "1"
    },

I see that env var is being passed while executing build script:

(19:52:28) �[34mSUBCOMMAND: �[0m# @crates_vendor__zstd-sys-2.0.6-zstd.1.5.2//:zstd-sys_build_script [action 'Running Cargo build script zstd-sys', configuration: ef19f56a583dd7ac1734bb42a08217760cb0ef37bcef77d6ee20ff7c144aebf6, execution platform: //rules/platforms:linux-u18-aarch64]
(cd /root/.cache/bazel/_bazel_root/fc1733654a4a8eb09c0d19e1b9713fea/execroot/dd_source && \
  exec env - \
    AR=/usr/bin/ar \
    CARGO_CRATE_NAME=zstd_sys \
    CARGO_ENCODED_RUSTFLAGS='--sysroot=${pwd}/bazel-out/aarch64-opt-exec-2EFC00D9/bin/external/rust_linux_aarch64__aarch64-unknown-linux-gnu__stable_tools/rust_toolchain\x1f--cap-lints=allow' \
    CARGO_FEATURE_DEFAULT=1 \
    CARGO_FEATURE_LEGACY=1 \
    CARGO_FEATURE_STD=1 \
    CARGO_FEATURE_ZDICT_BUILDER=1 \
    CARGO_MANIFEST_DIR=bazel-out/aarch64-opt-exec-2EFC00D9/bin/external/crates_vendor__zstd-sys-2.0.6-zstd.1.5.2/zstd-sys_build_script_.runfiles/crates_vendor__zstd-sys-2.0.6-zstd.1.5.2/ \
    CARGO_MANIFEST_LINKS=zstd \
    CARGO_PKG_NAME=zstd-sys \
    CARGO_PKG_VERSION=2.0.6+zstd.1.5.2 \
    CARGO_PKG_VERSION_MAJOR=2 \
    CARGO_PKG_VERSION_MINOR=0 \
    CARGO_PKG_VERSION_PATCH=6 \
    CARGO_PKG_VERSION_PRE='' \
    CC=/usr/bin/gcc \
    CC_ENABLE_DEBUG_OUTPUT=1 \
   ...

but I still don't see command executed under the hood.