[bootstrap] Replace old bootstrap with new bootstrap

[aciidgh]

We've successfully switched to the new bootstrap script so we can get
rid of the old bootstrap code now.

[aciidgh]

@swift-ci smoke test

[dan-zheng]

@aciidb0mb3r: I noticed that the new bootstrap strip no longer adds the @executable_path/../lib/swift/macosx RPATH to SwiftPM tool binaries like swift-build and swift-package.

This led to RPATH issues for toolchains built using build-toolchain-tensorflow (adapted from build-toolchain):

$ swift build
dyld: Library not loaded: @rpath/libswiftCore.dylib
  Referenced from: /Library/Developer/Toolchains/swift-tensorflow-DEVELOPMENT-2019-12-19-a.xctoolchain/usr/bin/swift-build
  Reason: image not found
[1]    45688 abort      swift build

I wonder if you encountered any similar issues?

---

A temporary fix was us is to re-add the @executable_path/../lib/swift/macosx RPATH for SwiftPM tool binaries.

$ sudo install_name_tool -add_rpath "@executable_path/../lib/swift/macosx" /Library/Developer/Toolchains/swift-tensorflow-DEVELOPMENT-2019-12-19-a.xctoolchain/usr/bin/swift-build
$ sudo install_name_tool -add_rpath "@executable_path/../lib/swift/macosx" /Library/Developer/Toolchains/swift-tensorflow-DEVELOPMENT-2019-12-19-a.xctoolchain/usr/bin/swift-package
$ sudo install_name_tool -add_rpath "@executable_path/../lib/swift/macosx" /Library/Developer/Toolchains/swift-tensorflow-DEVELOPMENT-2019-12-19-a.xctoolchain/usr/bin/swift-run
$ sudo install_name_tool -add_rpath "@executable_path/../lib/swift/macosx" /Library/Developer/Toolchains/swift-tensorflow-DEVELOPMENT-2019-12-19-a.xctoolchain/usr/bin/swift-test

The discussion at tensorflow/swift#347 has more context.

[dan-zheng]

I did some more investigation.

/usr/lib/swift is added as an RPATH for toolchains built from apple/swift:tensorflow branch, but not for toolchains built from apple/swift:master. This seems related to the build-script -toolchain-stdlib-rpath flag, which is true by default on tensorflow branch but false on master branch: code here.

To support toolchains built with -toolchain-stdlib-rpath=true (non-Swift-in-the-OS use cases), perhaps re-adding the @executable_path/../lib/swift/macosx RPATH in Utilities/bootstrap for SwiftPM tool binaries is a robust solution.

@aciidb0mb3r: does this solution make sense to you? SR-1967 seems like a related issue.

[ematejska]

@aciidb0mb3r: What do you think? Right now using the package manager is busted for Swift for Tensorflow toolchains due to this.

[ematejska]

Specifically what about the use-case of using a third-party toolchain on Darwin? They would not be using the OS version of the swift libs since they provide their own.

[aciidgh]

I think we can add a flag in the bootstrap script to add the rpath. Will that work for tensor flow?