pub fn probe_laid_down(cache: &Path) -> Result<PathBuf, String>Expand description
The compiled-in probe, on disk under cache, because python is handed a
path.
Named by its own digest under the cache this tool already owns, so it is
written once and can never be stale: a probe that changed is a different
name and the old file is simply not asked for. Three of the four ways the
probe is called pass it as argv[1], and the fourth is already using stdin
for the source it formats, so there is no reading it from a pipe.
Keeping the name in the file keeps it in a traceback, where somebody
debugging their own build() will read it — and a file under a cache is
still there when they go and look, which a temporary directory is not.
The cache is a parameter and not read from the environment in here: it is
this tool’s and never the store --store points at, and saying which of
the two it is at the call site is the whole difference.