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radicle-heartwood-lfs
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build: rerun-if-changed on .git/logs/HEAD, fix stale version on rebuild 

Without an explicit rerun-if-changed directive, cargo has no way to
know it needs to re-run this build script just because the current
commit changed -- by default it only reruns based on files inside
the crate's own source tree, and .git is entirely outside that. This
let GIT_HEAD/RADICLE_VERSION silently go stale: several `cargo
build`s in a row during this session kept reporting an old commit's
version despite the working tree being clean at a newer commit,
because cargo decided nothing needed rebuilding at all.

`.git/logs/HEAD` (the reflog) is touched on every commit, checkout,
and merge, unlike `.git/HEAD` itself (which only changes when
switching branches) -- watching it catches the case that actually
matters here.
This commit is contained in:
Maciek "mab122" Bator 2026-07-17 09:42:30 +02:00
parent 2306aabc4a
commit 581843fa92
1 changed files with 13 additions and 0 deletions
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13
build.rs
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@ -2,6 +2,19 @@ use std::env;
use std::process::Command;
fn main() -> Result<(), Box<dyn std::error::Error>> {
// Without this, cargo has no way to know it needs to re-run this
// script just because the current commit changed -- by default it
// only reruns a build script when a file inside the crate's own
// source tree changes, and `.git` is outside that entirely. That
// silently let GIT_HEAD/RADICLE_VERSION go stale on ordinary
// incremental rebuilds across commits that didn't happen to touch
// this crate's own sources (discovered live: several `cargo build`s
// in a row kept reporting an old commit's version despite the
// working tree being clean at a newer commit). `.git/logs/HEAD` (the
// reflog) is touched on every commit/checkout/merge, unlike
// `.git/HEAD` itself, which only changes when you switch branches.
println!("cargo::rerun-if-changed=../../.git/logs/HEAD");
// Set a build-time `GIT_HEAD` env var which includes the commit id;
// such that we can tell which code is running.
let hash = env::var("GIT_HEAD").unwrap_or_else(|_| {