Run CI against Xcode 12 beta

[dflems]

Originally tried this in #909 / #917 but reverted because Spectre wouldn't build with Xcode 12b3. It does build with b4, but GitHub Actions doesn't support it yet (incoming with actions/runner-images#1409)

This PR will probably initially fail but once 12b4 (12A8179i) is deployed on GH, it should pass on re-run 🤞

@yonaskolb (cc @brentleyjones)

[yonaskolb]

I saw that spectre has a new release for Xcode 12. We should probably update to that

[dflems]

@yonaskolb Unfortunately, it seems that Spectre 0.9.1 doesn't compile with beta 4 :(

Since GitHub is upgrading soon, it would work in the short term but then start failing once they roll up to beta 4.

/path/to/XcodeGen/.build/checkouts/Spectre/Sources/Spectre/XCTest@5.swift:11:21: error: 'XCTIssueReference' is not implicitly convertible to 'XCTIssue'; did you mean to use 'as' to explicitly convert?
    testCase.record(issue)
                    ^
                          as XCTIssue

[dflems]

@yonaskolb Re-triggered. Looks like CI has 12A8179i installed now so xcodegen built fine, but now Carthage is failing when setting up the project fixtures -_-

[dflems]

This will only set EXCLUDED_ARCHS if building with Xcode 12. It works around an issue where Carthage fails to create fat Simulator + Device binaries. For instance, creation of fat dylibs/archives fail because iphonesimulator builds targeting Apple silicon share the arm* archs with iphoneos. We'll probably need this workaround until Carthage supports xcframeworks or some other means of being able to build frameworks per-platform.

[dflems]

@yonaskolb Finally green after adding a workaround for Carthage 👍

The fixtures including Xcode-12+-only targets are now successfully building in CI.

[brentleyjones]

I heard that GitHub actions sometimes runs beta 4, but also sometimes runs beta 3 😕.

[dflems]

Oof. Then maybe we hold off until it's confirmed in the GH actions docs.

[dflems]

@yonaskolb @brentleyjones They merged actions/runner-images#1409 today, so I would assume the rollout is 100% complete for beta4 on GitHub Actions.

[yonaskolb]

Anything not related to Xcode 12, can we put in the actual spec? I'd like to have that as buildable as possible without custom xcodebuild args

[dflems]

@yonaskolb These were already explicit overrides in the script that built the fixtures. It made the command line a lot shorter to extract them to this xcconfig. They shouldn't go in the spec because they're only needed for CI builds (which does not have certs/profiles available to do code signing)

[dflems]

This was able to replace:

xcodebuild ... CODE_SIGN_IDENTITY="" CODE_SIGNING_REQUIRED=NO CODE_SIGN_ENTITLEMENTS="" CODE_SIGNING_ALLOWED="NO"

with:

xcodebuild ... -xcconfig fixtures.xcconfig

and apply the xcode 12 overrides all in one shot

[yonaskolb]

Right you are, apologies. My glance was too quick 😀