build: Consider SOURCE_DATE_EPOCH in Guix environment only

[hebasto]

The SOURCE_DATE_EPOCH environment variable is supposed to be used to achieve build reproducibility.

However, using it outside Guix scripts for local builds on macOS is not meaningful.

This PR makes usage of SOURCE_DATE_EPOCH for macOS consistent with other platforms and simplifies upcoming CMake-based build system scripts.

[DrahtBot]

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Concept NACK	fanquake

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #29790 ([DO NOT MERGE] cmake: Migrate CI scripts to CMake-based build system -- WIP by hebasto)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

[DrahtBot]

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_{Debug: https://github.com/bitcoin/bitcoin/runs/23219591618}

[hebasto]

Guix builds:

x86_64
ef12d060b4e4d74030586f9b49e8152e50365d46487bba4f2a659634ef7ee5f6  guix-build-b78b7f2ee77f/output/arm64-apple-darwin/SHA256SUMS.part
4e06e4a4943f9495311b5f4934bd40145a5b80b64254027f97d92425b4669413  guix-build-b78b7f2ee77f/output/arm64-apple-darwin/bitcoin-b78b7f2ee77f-arm64-apple-darwin-unsigned.tar.gz
5f0e1f2f4dcf7948870d11375a1acdc64a0bb2d921666474f4fdbe11914158dd  guix-build-b78b7f2ee77f/output/arm64-apple-darwin/bitcoin-b78b7f2ee77f-arm64-apple-darwin-unsigned.zip
5a0358db31223bcac44b3fd3b9058f12df0bf8b79ff0cdb047ae723303385f09  guix-build-b78b7f2ee77f/output/arm64-apple-darwin/bitcoin-b78b7f2ee77f-arm64-apple-darwin.tar.gz
c268e0729f45d442b1a767af4bb63d7940561fe331bda22c431a30f1ad03103b  guix-build-b78b7f2ee77f/output/dist-archive/bitcoin-b78b7f2ee77f.tar.gz
b4c7adbec6383abe7077f527b01648bb3b43173ba241b647d8a50ba1fede64a7  guix-build-b78b7f2ee77f/output/x86_64-apple-darwin/SHA256SUMS.part
4020b84e34860bf65373d9723d046a991a32c723f1f1a3dece6e7609b4fb3988  guix-build-b78b7f2ee77f/output/x86_64-apple-darwin/bitcoin-b78b7f2ee77f-x86_64-apple-darwin-unsigned.tar.gz
bb2f73676c6fadc814a97a3c0b06aaeeb5cce6456f0a395dc03102f76797e7cb  guix-build-b78b7f2ee77f/output/x86_64-apple-darwin/bitcoin-b78b7f2ee77f-x86_64-apple-darwin-unsigned.zip
b6f9d1e6e6cd7959f43f44d03dc8b958c7e648245452be2112b35a4e0c6af597  guix-build-b78b7f2ee77f/output/x86_64-apple-darwin/bitcoin-b78b7f2ee77f-x86_64-apple-darwin.tar.gz

[fanquake]

However, using it outside Guix scripts for local builds on macOS is not meaningful.

Why? Using Guix should not be a requirement for SOURCE_DATE_EPOCH to be useful. I would think that given the pinned compilers, and provisioned std lib, the macOS cross build would actually pretty be close to deterministic outside of Guix.

[fanquake]

What is the status of this?

[hebasto]

However, using it outside Guix scripts for local builds on macOS is not meaningful.

Why? Using Guix should not be a requirement for SOURCE_DATE_EPOCH to be useful.

Not a requirement. Both Guix and SOURCE_DATE_EPOCH are tools of the same domain, which is build reproducibility.

I would think that given the pinned compilers, and provisioned std lib, the macOS cross build would actually pretty be close to deterministic outside of Guix.

Is anyone interesting / working on that?

What is the status of this?

Under peer reviewing, I guess :)

[fanquake]

Is anyone interesting / working on that?

I'm saying it's likely already the case, without further changes.

Under peer reviewing, I guess :)

Ok. Concept NACK I guess. I don't see the motivation.