Not sure what this is about, is it a preexisting issue on master?

post-installation fixup
shrinking RPATHs of ELF executables and libraries in /nix/store/qfsz9zn71803bhwqzr8fmhkcbfp58762-bazel-watcher-0.10.3
shrinking /nix/store/qfsz9zn71803bhwqzr8fmhkcbfp58762-bazel-watcher-0.10.3/bin/ibazel
cannot find section .dynamic
strip is /nix/store/sq2b0dqlq243mqn4ql5h36xmpplyy20k-binutils-2.31.1/bin/strip
stripping (with command strip and flags -S) in /nix/store/qfsz9zn71803bhwqzr8fmhkcbfp58762-bazel-watcher-0.10.3/bin
patching script interpreter paths in /nix/store/qfsz9zn71803bhwqzr8fmhkcbfp58762-bazel-watcher-0.10.3
checking for references to /build/ in /nix/store/qfsz9zn71803bhwqzr8fmhkcbfp58762-bazel-watcher-0.10.3...
cannot find section .dynamic
error: build of '/nix/store/i33llps78bk1145jmkjx5vlmdg0fmamr-bazel-test-shebangs.drv' failed

This removes Bazel 2, which I don't think is what we want. I think a separate commit introducing Bazel 3 (bazel_3: init at 3.00) is in order, without changing the default.

correct, please leave the individual bazel version, then bazel_latest should just be aliased to whatever happens to be latest

don't want to end up with tensorflow broken for another 4 months

Tensorflow uses bazel_0_26 and bazel_0_29, and I saw a PR for a version of tensorflow that uses bazel_1, is there one that uses bazel_2? Rather than adding a new bazel derivation for each bazel version regardless of whether other derivations are using them or not, wouldn't it make sense to only add versions that are used? So rather than leave bazel_2 and add bazel_3 now, then bazel_4 etc, we can keep bazel_latest rolling, and add bazel_2 when we update tensorflow to a version that needs bazel_2, bazel_3 when we need that etc. And when we remove the last package that is using bazel_0_26 we can remove that.

That way we don't add more and more bazel derivations with no clear way of reducing the number of them.

Bazel releases a new major at most every 3 months, according to:

https://docs.google.com/document/d/1NCKLVwYMMp7Wjpb4-49FuVCWmQci6i4WZQVvm3u-WcI/edit#heading=h.t52pudpvuk1s

Bazel 1.0.0: 2019-10-10 https://github.com/bazelbuild/bazel/releases/tag/1.0.0
Bazel 2.0.0: 2019-12-19 https://github.com/bazelbuild/bazel/releases/tag/2.0.0
Bazel 3.0.0: 2020-04-06 https://github.com/bazelbuild/bazel/releases/tag/3.0.0

This is why I think there's too many version to keep them all regardless of whether another derivation is using them or not.

I can definitely see the use case where a future version of tensorflow requires bazel_2.

One possible policy would be to always keep

• The current release
• The last major release
• All releases that are currently in use

Keeping the last major release will make it possible to use a semi-recent version of bazel in packages like tensorflow which always lag behind a bit.

Tensorflow 2.1.0 (latest stable release) requires bazel 0.29; they're currently doing the release candidates for 2.2.0, which looks like it's going to be on bazel 3.0:
tensorflow/tensorflow@2f65c24

So it might be OK to drop bazel 2.0.

Rebased on current master to see if the issue is still there.

ping @mboes @kalbasit @Profpatsch

I'm still getting the same error, but I haven't figured out how to reproduce it locally.

We can revive bazel versions posthumously if some package upgrades to an older version.

Agreed, I'd say delete old bazel versions, unless it's actually being used by something that can't upgrade to a newer one.

Huh @uri-canva, what’s the reason this PR was closed?

I never managed to figure out the reason behind this error on ofborg:

post-installation fixup
shrinking RPATHs of ELF executables and libraries in /nix/store/qfsz9zn71803bhwqzr8fmhkcbfp58762-bazel-watcher-0.10.3
shrinking /nix/store/qfsz9zn71803bhwqzr8fmhkcbfp58762-bazel-watcher-0.10.3/bin/ibazel
cannot find section .dynamic
strip is /nix/store/sq2b0dqlq243mqn4ql5h36xmpplyy20k-binutils-2.31.1/bin/strip
stripping (with command strip and flags -S) in /nix/store/qfsz9zn71803bhwqzr8fmhkcbfp58762-bazel-watcher-0.10.3/bin
patching script interpreter paths in /nix/store/qfsz9zn71803bhwqzr8fmhkcbfp58762-bazel-watcher-0.10.3
checking for references to /build/ in /nix/store/qfsz9zn71803bhwqzr8fmhkcbfp58762-bazel-watcher-0.10.3...
cannot find section .dynamic
error: build of '/nix/store/i33llps78bk1145jmkjx5vlmdg0fmamr-bazel-test-shebangs.drv' failed

I switched to using bazelisk from nix and instead of bazel, and letting bazelisk get bazel, so I closed this PR so other people wouldn't get blocked on it and could start their own attempts to upgrade.

FYI Tensorflow 2.2 build with bazel 2.0.0