the .cargo/config.toml rustflags did not passed to the compiler

[jiangxiaoqiang]

When I migrate the rustflags from command line to config files, the rustflags did not passed to the compiler. I am compile the project with FFI using command like this:

RUSTFLAGS='-L ./src/so' cargo build

it works fine. but when I changed to the config file:

[build]
rustflags = ["-L", "/Users/xiaoqiangjiang/source/reddwarf/backend/rust-learn/src/so"]

could not compile the project.

I tried this code:

[build]
rustflags = ["-L", "/Users/xiaoqiangjiang/source/reddwarf/backend/rust-learn/src/so"]

I expected to see this happen:

both using command and config could compile the project success.

Instead, this happened:

command line works, config file failed.

Meta

rustc --version --verbose:

> rustc --version --verbose
rustc 1.72.1 (d5c2e9c34 2023-09-13)
binary: rustc
commit-hash: d5c2e9c342b358556da91d61ed4133f6f50fc0c3
commit-date: 2023-09-13
host: aarch64-apple-darwin
release: 1.72.1
LLVM version: 16.0.5

the minimal reproduce example:

git clone -b rustflags https://github.com/jiangxiaoqiang/rust-learn.git

there is the similiar issue told that maybe rustc issue: #4452

[weihanglo]

Could you run cargo build --verbose and check if there is -L /Users/xiaoqiangjiang/source/reddwarf/backend/rust-learn/src/so being passed?

Also, there are a list of precedence of how Cargo picks rustflags config. Please see the order and check if your build.rustflags was overriden by other configs.

[jiangxiaoqiang]

Could you run cargo build --verbose and check if there is -L /Users/xiaoqiangjiang/source/reddwarf/backend/rust-learn/src/so being passed?

Also, there are a list of precedence of how Cargo picks rustflags config. Please see the order and check if your build.rustflags was overriden by other configs.

I have checked, there is no -L /Users/xiaoqiangjiang/source/reddwarf/backend/rust-learn/src/so passed. I have checked the order and there is no config overriden the rustflags from file. Actually I found many places mention this issue, it looks like a bug.

[weihanglo]

Thanks for the reply. I can reproduce it with provided repo and found there is -L /Users/xiaoqingjiang/... in every rustc invocation.

Could you check if CARGO_ENCODED_RUSTFLAGS or RUSTFLAGS were passed as an empty string? Any empty string of them would also take precedence over build.rustflags config value.

I would also suggest using cargo +nightly -Z unstable-options config get --show-origin and check the config values. If possible, please remove sensitive data and share the output.

I found many places mention this issue, it looks like a bug.

Could you point them out? At this moment with limited info, I cannot see any issue related to this one, except #12087 which talks about bad discovery of rustflags override chain.

[jiangxiaoqiang]

wired. I am check the "-L", "/Users/xiaoqiangjiang/source/reddwarf/backend/rust-learn/src/so" in the build.log file generate by command:

cargo build --verbose &> build.log

there is no path /Users/xiaoqiangjiang/source/reddwarf/backend/rust-learn/src/so with L parameter. Am I doing this the right way? this is the config:

> cargo +nightly -Z unstable-options config get --show-origin
alias.b = "build" # /Users/xiaoqiangjiang/source/reddwarf/backend/texhub-server/.cargo/config.toml
build.rustflags = [
    "-L", # /Users/xiaoqiangjiang/source/reddwarf/backend/texhub-server/.cargo/config.toml
    "/Users/xiaoqiangjiang/source/reddwarf/backend/texhub-server/src/so", # /Users/xiaoqiangjiang/source/reddwarf/backend/texhub-server/.cargo/config.toml
]
source.crates-io.registry = "https://github.com/rust-lang/crates.io-index" # /Users/xiaoqiangjiang/.cargo/config
source.crates-io.replace-with = "tuna" # /Users/xiaoqiangjiang/.cargo/config
source.rustcc.registry = "git://crates.rustcc.cn/crates.io-index" # /Users/xiaoqiangjiang/.cargo/config
source.sjtu.registry = "https://mirrors.sjtug.sjtu.edu.cn/git/crates.io-index" # /Users/xiaoqiangjiang/.cargo/config
source.tuna.registry = "https://mirrors.tuna.tsinghua.edu.cn/git/crates.io-index.git" # /Users/xiaoqiangjiang/.cargo/config
source.ustc.registry = "git://mirrors.ustc.edu.cn/crates.io-index" # /Users/xiaoqiangjiang/.cargo/config
# The following environment variables may affect the loaded values.
# CARGO_HOME=/Users/xiaoqiangjiang/.cargo

from the config it look like the config make effect but I could not build the project using cargo build, thow the error:

"/Users/xiaoqiangjiang/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libcore-49cb3ef59194e1e6.rlib" "/Users/xiaoqiangjiang/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libcompiler_builtins-40415e957020687a.rlib" "-framework" "Security" "-framework" "Security" "-lpq" "-framework" "CoreFoundation" "-lssl" "-lcrypto" "-liconv" "-lSystem" "-lc" "-lm" "-L" "/Users/xiaoqiangjiang/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib" "-o" "/Users/xiaoqiangjiang/source/reddwarf/backend/texhub-server/target/debug/deps/texhub_server-c2cd989f5bc32ef7" "-Wl,-dead_strip" "-nodefaultlibs"
  = note: ld: warning: directory not found for option '-L/System/Volumes/Data/opt/homebrew/Cellar/libpq/15.2/lib'
          ld: library not found for -lsynctex_parser
          clang: error: linker command failed with exit code 1 (use -v to see invocation)

[jiangxiaoqiang]

sorry my mistake, it seems the env RUSTFLAGS config override the rustflags. I found the config:

> env|grep "RUSTFLAGS"
RUSTFLAGS=-L /System/Volumes/Data/opt/homebrew/Cellar/libpq/15.2/lib