std.pcm was rebuilt when it was older than std.cppm, and project.so when
it was older than the crafter-build executable. Both inputs are installed
files, and an OSTree deployment (the Flatpak) gives every installed file
mtime 0: std.cppm and the executable always looked older than the cache,
so a clang bump would never rebuild std.pcm and a crafter-build update
would never recompile project.so. clang crashes on a PCM from another
compiler instead of reporting it, so the failure would have been a
backtrace on the user's first build after an update.
Each artifact now has a one-line stamp beside it. std.pcm's covers the
precompile command and the module source's bytes, which also catches a
libc++ update under the same clang. project.so's covers the crafter-build
version, the toolchain key, the module source stamp and the compile
command; project.cpp's and the pre-dependency artifacts' mtimes remain
inputs, since those live next to it with real timestamps. The module
source stamp stands in for the executable: project.so resolves Crafter::
symbols from the running binary, so only declarations matter, and an
implementation-only rebuild of crafter-build no longer recompiles it.
The std.pcm stamp folds into the module cache stamp, so a rebuilt
std.pcm rebuilds the PCMs that import it.
The cache directory carries the toolchain key
(<target>-<march>-<clang version>-<hash>), so a compiler bump starts
cold instead of handing the new clang PCMs it will crash on. LoadProject
and Build() now derive the directory from the same StdPcmDir. Old
<target>-<march> directories are left behind; `clean` never touched the
cache and still does not.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Jorijn van der Graaf
59fc9501f1