cargo エラー The system library `alsa` required by crate `alsa-sys` was not found の修正方法

問題

cargo build または cargo run の実行中に、次のようなエラーメッセージが表示されます:

cargo-alsa-sys-error.txt

   Compiling euclid v0.22.11
error: failed to run custom build command for `alsa-sys v0.3.1`

Caused by:
  process didn't exit successfully: `/home/uli/dev/MyProject/target/debug/build/alsa-sys-d857244a3626a86f/build-script-build` (exit status: 101)
  --- stdout
  cargo:rerun-if-env-changed=ALSA_NO_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG
  cargo:rerun-if-env-changed=ALSA_STATIC
  cargo:rerun-if-env-changed=ALSA_DYNAMIC
  cargo:rerun-if-env-changed=PKG_CONFIG_ALL_STATIC
  cargo:rerun-if-env-changed=PKG_CONFIG_ALL_DYNAMIC
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR

  --- stderr

  thread 'main' (911284) panicked at /home/uli/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/alsa-sys-0.3.1/build.rs:13:18:

  pkg-config exited with status code 1
  > PKG_CONFIG_ALLOW_SYSTEM_LIBS=1 PKG_CONFIG_ALLOW_SYSTEM_CFLAGS=1 pkg-config --libs --cflags alsa

  The system library `alsa` required by crate `alsa-sys` was not found.
  The file `alsa.pc` needs to be installed and the PKG_CONFIG_PATH environment variable must contain its parent directory.
  The PKG_CONFIG_PATH environment variable is not set.

  HINT: if you have installed the library, try setting PKG_CONFIG_PATH to the directory containing `alsa.pc`.

  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...

解決方法

Rust プロジェクトは alsa クレートに依存しており、そのクレートはシステムの ALSA ライブラリに依存しています。

Ubuntu では、次のコマンドでインストールできます:

install-libasound2-dev.sh

sudo apt -y install libasound2-dev

その後、cargo コマンドを再試行できます。