Continual recompliation of blake3

[justinabrahms]

Blake3 is in my transitive dependency chain. When I edit my code, it recompiles every time. It seems to believe that the environment variable is changing.. but I'm just editing a file, nothing more.

Most seemingly relevant line below.

[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: EnvVarChanged { name: "CC", old_value: None, new_value: Some("gcc") }

Thoughts?

$ CARGO_LOG=cargo::core::compiler::fingerprint=info cargo build
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] dependency on `build_script_build` is newer than we are 1689140428.554280381s > 1689140320.333216314s "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/blake3-1.4.0"
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for WORK_CODE v0.1.0 (/home/abrahms/src/github.com/subconsciousnetwork/WORK_CODE)/Build/TargetInner { name: "WORK_PACKAGE", doc: true, ..: with_path("/home/abrahms/src/github.com/subconsciousnetwork/WORK_CODE/src/main.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for cid v0.10.1/Build/TargetInner { ..: lib_target("cid", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/cid-0.10.1/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "multihash", old_fingerprint: 5789376448465686996, new_name: "multihash", new_fingerprint: 15717749769461962212 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for multihash v0.18.1/Build/TargetInner { ..: lib_target("multihash", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/multihash-0.18.1/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "blake3", old_fingerprint: 11447239697517040600, new_name: "blake3", new_fingerprint: 9816954190456901003 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for blake3 v1.4.0/Build/TargetInner { ..: lib_target("blake3", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/blake3-1.4.0/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "build_script_build", old_fingerprint: 13742670213903239432, new_name: "build_script_build", new_fingerprint: 991342934240953990 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for blake3 v1.4.0/RunCustomBuild/TargetInner { ..: custom_build_target("build-script-build", "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/blake3-1.4.0/build.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: EnvVarChanged { name: "CC", old_value: None, new_value: Some("gcc") }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for libipld v0.16.0/Build/TargetInner { ..: lib_target("libipld", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/libipld-0.16.0/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "libipld_json", old_fingerprint: 17084127054727942497, new_name: "libipld_json", new_fingerprint: 5921226181653514756 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for libipld-cbor v0.16.0/Build/TargetInner { ..: lib_target("libipld-cbor", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/libipld-cbor-0.16.0/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "libipld_core", old_fingerprint: 13071416919958757996, new_name: "libipld_core", new_fingerprint: 17725040881794123426 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for libipld-core v0.16.0/Build/TargetInner { ..: lib_target("libipld-core", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/libipld-core-0.16.0/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for libipld-json v0.16.0/Build/TargetInner { ..: lib_target("libipld-json", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/libipld-json-0.16.0/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "libipld_core", old_fingerprint: 13071416919958757996, new_name: "libipld_core", new_fingerprint: 17725040881794123426 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for libipld-macro v0.16.0/Build/TargetInner { ..: lib_target("libipld-macro", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/libipld-macro-0.16.0/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "libipld_core", old_fingerprint: 13071416919958757996, new_name: "libipld_core", new_fingerprint: 17725040881794123426 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for libipld-pb v0.16.0/Build/TargetInner { ..: lib_target("libipld-pb", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/libipld-pb-0.16.0/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "libipld_core", old_fingerprint: 13071416919958757996, new_name: "libipld_core", new_fingerprint: 17725040881794123426 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for noosphere-api v0.9.1/Build/TargetInner { ..: lib_target("noosphere-api", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/noosphere-api-0.9.1/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for noosphere-car v0.2.0/Build/TargetInner { ..: lib_target("noosphere-car", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/noosphere-car-0.2.0/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for noosphere-core v0.13.1/Build/TargetInner { ..: lib_target("noosphere-core", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/noosphere-core-0.13.1/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for noosphere-collections v0.6.1/Build/TargetInner { ..: lib_target("noosphere-collections", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/noosphere-collections-0.6.1/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for noosphere-storage v0.7.1/Build/TargetInner { ..: lib_target("noosphere-storage", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/noosphere-storage-0.7.1/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for ucan v0.4.0/Build/TargetInner { ..: lib_target("ucan", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/ucan-0.4.0/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for ucan-key-support v0.1.7/Build/TargetInner { ..: lib_target("ucan-key-support", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/ucan-key-support-0.1.7/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "ucan", old_fingerprint: 14090303343170715210, new_name: "ucan", new_fingerprint: 9002932740954988695 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for dummy-ns v0.1.0 (/home/abrahms/src/github.com/subconsciousnetwork/WORK_CODE2)/Build/TargetInner { name: "dummy-ns", doc: true, ..: with_path("/home/abrahms/src/github.com/subconsciousnetwork/WORK_CODE2/src/main.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for noosphere-ns v0.9.1/Build/TargetInner { ..: lib_target("noosphere-ns", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/noosphere-ns-0.9.1/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for noosphere v0.12.1/Build/TargetInner { ..: lib_target("noosphere", ["rlib", "staticlib", "cdylib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/noosphere-0.12.1/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for noosphere-sphere v0.7.1/Build/TargetInner { ..: lib_target("noosphere-sphere", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/noosphere-sphere-0.7.1/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint] fingerprint dirty for noosphere-ipfs v0.6.1/Build/TargetInner { ..: lib_target("noosphere-ipfs", ["lib"], "/home/abrahms/.cargo/registry/src/index.crates.io-6f17d22bba15001f/noosphere-ipfs-0.6.1/src/lib.rs", Edition2021) }
[2023-07-12T05:41:37Z INFO  cargo::core::compiler::fingerprint]     dirty: UnitDependencyInfoChanged { old_name: "cid", old_fingerprint: 2196727044934558216, new_name: "cid", new_fingerprint: 7776841732667268909 }

[max-niederman]

I'm also having this issue.

[oconnor663]

build.rs contains these lines, which might be related:

    // The `cc` crate doesn't automatically emit rerun-if directives for the
    // environment variables it supports, in particular for $CC. We expect to
    // do a lot of benchmarking across different compilers, so we explicitly
    // add the variables that we're likely to need.
    println!("cargo:rerun-if-env-changed=CC");
    println!("cargo:rerun-if-env-changed=CFLAGS");

I'd be curious if removing those lines fixes the issue for you. That wouldn't tell us the whole story, but it would be a big part. Also, can you reproduce this issue in any open source project that I could also build for myself. It would help to see it happen on my own machine.

[max-niederman]

Yeah, it's almost certainly to do with those rerun directives.

I was messing around with it earlier and I did notice that it only ever happens in my VS Code terminal, which is quite weird. There are a lot of moving parts w.r.t. the terminal in my particular project because I'm using a Nix shell w/ Direnv, so it's going to be a bit difficult to track down the issue, but I'll set aside some time tomorrow to work on a minimal reproduction.

[pyranota]

I have similar problem on Voidlinux. But with small difference: dirty: EnvVarChanged { name: "CC", old_value: Some("gcc"), new_value: None }. I found a workaround for this. In my case worked exporting CC and AR manually:

1. export CC=gcc
2. export AR=ar