Disable the shorten-64-to-32 warning in Package.swift

[ahoppen]

Without this flag, we get about 40 warnings when building swift-lmdb in Xcode. I don’t think there is an immediate plan to address them in upstream lmdb, so let’s disable them.

[d-ronnqvist]

If I understand the unsafeFlags(_:_:) documentation correctly, this change would prevent other packages from using the CLMDB library product:

As some build flags can be exploited for unsupported or malicious behavior, the use of unsafe flags makes the products containing this target ineligible for use by other packages.

[d-ronnqvist]

IIUC this will prevent other packages from using the only product in this package.

Please verify that other packages can still use the CLMDB library product with this change.

[ahoppen]

People won’t be able to depend on swift-lmdb with a version-based dependency but swift-lmdb doesn’t have any versioned releases, so this should be fine. Toolchain builds passed in swiftlang/swift#37710 and I am able to have a branch-based dependency on swift-lmdb with this change.

[d-ronnqvist]

Thanks for verifying that other packages can continue to use the CLMDB library product with this change. That addresses my concerns.

[vsarunas]

This is actually very confusing actually. LMDB does have versioning, but Github copy is only a a mirror and those tags are lagging behind the self hosted Gitlab where development is being done: https://git.openldap.org/openldap/openldap/-/tags?sort=updated_desc&search=lmdb_ , which also has CHANGES.

The Swift package doesn't have versioning which follows LMDB, but only follows Swift toolchain versioning.