[swift-dev] Call for help: Linux (and others) build configurations, including static libraries, with ICU.

[Michael Ilseman]

With https://github.com/apple/swift/pull/9684 the Swift standard library depends on ICU on Darwin in addition to Linux, where it has always had that dependency. While our Linux bots have been happy with the changes, I’m not familiar with the build configurations involving the build-your-own-ICU path, nor with FreeBSD, Cygwin, Android, etc. I would like to make sure that all supported configurations still work, can someone help me with this? 

Additionally, the standard library can be built as a static library. In this configuration, user programs that link against the static library should also be told explicitly to link against ICU (e.g. “-licu*”). On Darwin, the least evil approach was autolinking by emitting a linker option via inline asm in the shims library. Is there an approach that would work for Linux? An alternative solution could be adding the flags in the Swift driver itself, but that would mean that any build systems that bypass the Swift driver would also need to be updated to pass those same flags.