Being able to reproduce the binary from the source code and being able to verify that it's the same as the original is quite important in some contexts.
I disagree. The contexts that people come up with are purely theoretical, and are not practically important. Please do try and convince me otherwise by sharing such a context. From my view the juice of trying to accomplish this is no where worth the squeeze.
Military context: a government would want to review the code and compile themselves. Provide a hash of the target binary to ensure they've compiled it correctly.
SDLC: provide auditors with _proof_ that the tested binary is indeed coming from the audited code
SDLC: Traceability is more important than reproducibility. Keeping logs is more important than deterministic build outputs
The government doesn't want to do this. A lot of the time the government doesn't even get the source code in the first place.
>provide auditors with _proof_ that the tested binary is indeed coming from the audited code
This can be done by showing to the auditor how one's CI is setup to build checked in code and sign it.
Why not build your own binaries and be done with that. If you don’t trust the compiler or the machine doing the build, just build the code yourself.
Also useful for checking that a binary containing GPLed code does actually correspond to its published source.