1320728 - Verify programs at beginning of the build

Status: NEW

(Firefox Build System :: General, defect)

Description

[Gregory Szorc [:gps]]

There's a longstanding problem in the build system where a binary as detected by configure can change (or be removed). The build system doesn't actively look for these changes and this can result in broken builds.

(We just had a report on dev-platform of rust/cargo in /usr/local/bin being removed and an incremental build being broken because binaries disappeared.)

I think we should be a bit more proactive about detecting certain changes. As a start, we could stat every program detected by configure and verify it still exists. If it doesn't, we would automatically re-execute configure.

A more robust solution would be to compare mtimes of programs. An even more robust solution would be to hash programs and verify they haven't changed.

Historically, I don't think we did much about this because configure was a mess. But with moz.configure, I think we're in a much better position to do this. e.g. everything detected by check_prog() could be written out to a manifest and we could verify the manifest before invoking the build backend.