GitHub Actions not creating Rust binaries

Question

I am using GitHub Actions to cross-compile my Rust program. The action completes successfully, and files are created in the target directory, but there is no binary. This is my workflow file:

name: Compile and save program

on:
  push:
    branches: [main]
    paths-ignore: ["samples/**", "**.md"]
  workflow_dispatch:
    
jobs:    
  build:
    strategy:
      fail-fast: false
      matrix:
        target: 
          - aarch64-unknown-linux-gnu
          - i686-pc-windows-gnu
          - i686-unknown-linux-gnu
          - x86_64-pc-windows-gnu
          - x86_64-unknown-linux-gnu
          
    name: Build executable
    runs-on: ubuntu-latest
    
    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
      - name: Set up Rust
        uses: actions-rs/toolchain@v1
        with:
          toolchain: stable
      - name: Install dependencies
        run: |
          rustup target add ${{ matrix.target }}
      - name: Build
        uses: actions-rs/cargo@v1
        with:
          use-cross: true
          command: build
          args: --target ${{ matrix.target }} --release --all-features --target-dir=/tmp
      - name: Debug missing files
        run: |
          echo "target dir:"
          ls -a /tmp/release
          echo "deps:"
          ls -a /tmp/release/deps
      - name: Archive production artifacts
        uses: actions/upload-artifact@v3
        with:
          name: ${{ matrix.target }}
          path: |
            /tmp/release

And this is the layout of the created directory when targeting Windows x86_64 (the only difference when targeting other platforms is the names of the directories within .fingerprint and build):

.
├── .cargo-lock
├── .fingerprint/
│   ├── libc-d2565b572b77baea/
│   ├── winapi-619d3257e8f28792/
│   └── winapi-x86_64-pc-windows-gnu-7e7040207fbb5417/
├── build/
│   ├── libc-d2565b572b77baea/
│   ├── winapi-619d3257e8f28792/
│   └── winapi-x86_64-pc-windows-gnu-7e7040207fbb5417/
├── deps/
│   └── <empty>
├── examples/
│   └── <empty>
└── incremental/
    └── <empty>

As you can see, there is no binary, and this is reflected in the uploaded artifact.

What is causing this?

EDIT 1

The program builds fine on my local device. My .cargo/config.toml is below.

[target.aarch64-unknown-linux-gnu]
linker = "aarch64-linux-gnu-gcc"

And this is my Cargo.toml:

[package]
name = "brainfuck"
version = "0.4.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
console = "0.15.2"
either = "1.8.0"

EDIT 2

While messing around in a test repo, I discovered that this issue only arises when specifying the target. If I don’t specify a target and just use the default system target, I get a binary as expected.

Answer 1

It turns out I didn’t read the cargo docs properly. The build cache docs mention that the results of a build with a specified target are stored in target/<triple>/debug/, and that is indeed where they were.