Remove previously deprecated --enable-test-discovery

[MaxDesiatov]

This flag was deprecated for 4 years since Swift 5.4, Swift 6.0 is a good opportunity to remove it.

Closes #7389.

[MaxDesiatov]

@swift-ci test

[MaxDesiatov]

@swift-ci test

[MaxDesiatov]

@swift-ci test windows

[grynspan]

I've asked @stmontgomery to also review this change, but I'm glad to see this flag go.

I think there are some unit tests you'll also need to revise or delete while you're in here.

[MaxDesiatov]

@swift-ci test

[MaxDesiatov]

@swift-ci test windows

[MaxDesiatov]

@swift-ci test

[MaxDesiatov]

@swift-ci test windows

[MaxDesiatov]

@swift-ci test

[MaxDesiatov]

@swift-ci test windows

[MaxDesiatov]

@swift-ci test windows

[MaxDesiatov]

@yim-lee @ktoso I see a few repositories you worked on still have LinuxMain.swift. Especially if any of those had fatalError in them requiring users to pass --enable-test-discovery, it's best to delete those files at this point and use plain swift test when Swift 6.0 is released.

[ktoso]

Sounds good, we only support swift 5.7+ nowadays in most telos so we can drop it I think.

Swift log I think supports ancient versions but we can maybe stop testing on them or something... I'll think about it

[yim-lee]

Thanks for the heads-up @MaxDesiatov.

I see a few repositories you worked on still have LinuxMain.swift.

Is LinuxMain.swift ignored in newer Swift versions?

Especially if any of those had fatalError in them requiring users to pass --enable-test-discovery

We have repos that pass --enable-test-discovery even in newer versions, but I don't think any of them does fatalError. Nevertheless, we will adjust the build params as needed once this change gets merged.

@ktoso I guess we should consider bumping up the Swift version requirement if we run into trouble removing --enable-test-discovery/LinuxMain.swift. At some point it doesn't make much sense to support ancient Swift versions.

[MaxDesiatov]

Is LinuxMain.swift ignored in newer Swift versions?

It's only ignored when you pass --enable-test-discovery, and with this PR merged in Swift 6.0 that flag won't longer be available, we'll always use LinuxMain.swift or XCTMain.swift if those are present.

[yim-lee]

Got it. Thanks @MaxDesiatov.

[grynspan]

we'll always use LinuxMain.swift or XCTMain.swift if those are present.

Don't we want to stop using it?

[MaxDesiatov]

Don't we want to stop using it?

IDK, if we do we'd have to go through a deprecation cycle with those for at least a few releases first. This PR is about that one test discovery flag specifically.