FIXME: swift/validation-test/stdlib/Set.swift:95

[frootloops]

Use real arc4random_uniform() instead of just random() % max

1. Is truncatingBitPattern proper way to prevent integer overflow?
2. Does UInt32 available on every platform?

Off topic question:

Why do you use if true {} in test cases? Is it equivalent for do {}?

[gparker42]

No, UInt32(truncatingBitPattern:) is not the right answer here. If the max value passed to uniformRandom() is too bit to fit in a UInt32 then truncatingBitPattern: will silently shrink it. Then the random numbers you get are in fact not uniform in the requested range.

UInt32 is available on every platform. There is a platform difference with Int: Int is only 32 bits on 32-bit platforms. That will make your Int() conversion fail when arc4random_uniform's result is too big.

This is only a test and it looks like we only call uniformRandom with small values. In that case it should be fine to use checked conversions to UInt32 and back to Int. They will never fail with the tests as written today, and if something does fail someday then we can write a more complicated fix.

[gparker42]

The if true statements probably pre-date the existence of do. IIRC do was added late in the development of Swift 2.0.

[frootloops]

@gparker42 thanks for comments. I have updated the PR. Is that ok?

[gribozavr]

Looks good, thanks!