Run CI dependency checks on a Mac, to properly detect iOS-specific dependencies

[rfk]

Trying to debug failing dependency checks in CI that we can't reproduce locally.

[codecov-commenter]

Codecov Report

Merging #3565 into main will increase coverage by 7.20%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3565      +/-   ##
==========================================
+ Coverage   69.47%   76.67%   +7.20%     
==========================================
  Files         230      230              
  Lines       30879    30879              
==========================================
+ Hits        21453    23677    +2224     
+ Misses       9426     7202    -2224     

Impacted Files	Coverage Δ
components/fxa-client/src/device.rs	78.21% <0.00%> (+1.83%)	⬆️
components/support/guid/src/lib.rs	97.94% <0.00%> (+2.56%)	⬆️
components/viaduct/src/headers.rs	72.47% <0.00%> (+2.75%)	⬆️
components/support/rc_crypto/nss/src/ec.rs	94.49% <0.00%> (+3.21%)	⬆️
components/sync15/src/key_bundle.rs	85.58% <0.00%> (+3.60%)	⬆️
components/support/sync15-traits/src/telemetry.rs	92.39% <0.00%> (+5.07%)	⬆️
components/sync15/src/bso_record.rs	98.48% <0.00%> (+5.55%)	⬆️
components/support/rc_crypto/src/hawk_crypto.rs	89.70% <0.00%> (+5.88%)	⬆️
components/sync15/src/request.rs	95.25% <0.00%> (+6.67%)	⬆️
...ents/support/sync15-traits/src/server_timestamp.rs	87.71% <0.00%> (+7.01%)	⬆️
... and 28 more

---

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[rfk]

OK so, when calculating the dependency list in CI, this is discarding some but not all of the new dependencies introduced by glean:

RuntimeError: Dependency details have changed from those in ./DEPENDENCIES.md:
--- 
+++ 
@@ -12,7 +12,6 @@
 * [MIT License: bincode](#mit-license-bincode)
 * [MIT License: bytes](#mit-license-bytes)
 * [MIT License: caseless](#mit-license-caseless)
-* [MIT License: dashmap](#mit-license-dashmap)
 * [MIT License: h2](#mit-license-h2)
 * [MIT License: http-body](#mit-license-http-body)
 * [MIT License: hyper](#mit-license-hyper)
@@ -24,7 +23,6 @@
 * [MIT License: mio](#mit-license-mio)
 * [MIT License: openssl-sys](#mit-license-openssl-sys)
 * [MIT License: ordered-float](#mit-license-ordered-float)
-* [MIT License: oslog](#mit-license-oslog)
 * [MIT License: schannel](#mit-license-schannel)
 * [MIT License: slab](#mit-license-slab)
 * [MIT License: synstructure](#mit-license-synstructure)
@@ -434,7 +432,6 @@
 
 The following text applies to code linked from these dependencies:
 [adler](https://github.com/jonas-schievink/adler.git),
-[ahash](https://github.com/tkaitchuck/ahash),
 [android_log-sys](https://github.com/nercury/android_log-sys-rs),
 [android_logger](https://github.com/Nercury/android_logger-rs),
 [anyhow](https://github.com/dtolnay/anyhow),
@@ -444,8 +441,6 @@
 [cc](https://github.com/alexcrichton/cc-rs),
 [cfg-if](https://github.com/alexcrichton/cfg-if),
 [chrono](https://github.com/chronotope/chrono),
-[const-random-macro](https://github.com/tkaitchuck/constrandom),
-[const-random](https://github.com/tkaitchuck/constrandom),
 [core-foundation-sys](https://github.com/servo/core-foundation-rs),
 [core-foundation](https://github.com/servo/core-foundation-rs),
 [crc32fast](https://github.com/srijs/rust-crc32fast),
@@ -508,7 +503,6 @@
 [pin-utils](https://github.com/rust-lang-nursery/pin-utils),
 [pkg-config](https://github.com/rust-lang/pkg-config-rs),
 [ppv-lite86](https://github.com/cryptocorrosion/cryptocorrosion),
-[proc-macro-hack](https://github.com/dtolnay/proc-macro-hack),
 [proc-macro2](https://github.com/alexcrichton/proc-macro2),
 [prost-derive](https://github.com/danburkert/prost),
 [prost](https://github.com/danburkert/prost),

Following the chain of dependencies reported in Cargo.lock, these all seem to be unique dependencies of oslog. Glean itself takes a platform-specific dependency on oslog like this:

[target.'cfg(target_os = "ios")'.dependencies]
oslog = { version = "0.0.3", default-features = false, features = ["logger"] }

So maybe this is not being activated in the build plan on CI, but is being activated in build plans when running locally.

[rfk]

Aha! As of #1720 the dependency checks run on a linux machine rather than a Mac.

Unfortunately, this script can't properly detect iOS-specific dependencies when run on anything other than a Mac, for dumb Mac platform lockin reasons. I'm going to revert the above change.

[rfk]

@eoger I'm going to merge this to unbreak CI, but we can have a broader conversation about the CI costs involved here if necessary. (For the record, I hate this this platform-specific stuff is necessary here 🤮)

[badboy]

For dependency checks we shouldn't need to compile, so running with --target aarch64-apple-ios should be possible.

[rfk]

The specific command that we end up trying to use here would be something like:

cargo +nightly -Z unstable-options build --build-plan --quiet --locked --package megazord_ios --target aarch64-apple-ios

Which fails for me with:

error: Error loading target specification: failed to get iphoneos SDK path: No such file or directory

But it's been a while since we touched this stuff, there may be a different command to use to get the info we need here.

[badboy]

Ah, I didn't actually check which command gets run.
It's not clear if build plans will stay so I guess this is a good point in time to find out if there's a more stable way to get the info we need.

[rfk]

Oh, interesting, thanks!

I had an earlier version of this script that used cargo tree rather than the buildplan, but IIRC it had the same problem with needing to run on a Mac.

[rfk]

I filed #3572 to surface the unsupportedness of buildplans as an independent issue for us to deal with.