Driver: look for the runtime object in the SDK

[compnerd]

The runtime object is for the host, and is part of the SDK. If -sdk
is passed, look for the runtime support object relative to the SDK root.

Replace this paragraph with a description of your changes and rationale. Provide links to external references/discussions if appropriate.

Resolves SR-NNNN.

[compnerd]

@swift-ci please test and merge

[compnerd]

@swift-ci please test

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 945917ce4ca3011fa40505a93ffcf995687dcbb1

[jrose-apple]

I think you mean "target", not "host". (This looks fine to me.)

[jrose-apple]

…although in the future I don't know if we really want to assume "using a non-Darwin SDK" = "cross-compiling".

[compnerd]

"target" is the wrong term, "host" is what the binary will run on. "target" is only used when cross-compiling a non-cross-compiling compiler. This is the de-facto terminology used across most Unices: https://www.gnu.org/software/automake/manual/html_node/Cross_002dCompilation.html

Your second point cannot be over-stressed. This is purely intended as a temporary workaround. The problem is that the change to look for the libraries in the SDK was reverted and I am just waiting on that to go back in as that would allow us to drop that invalid condition. I didn't want to break the Darwin target, but I agree that it is incorrect.

[compnerd]

CC: @brentdax - you may also care about this since you are doing something related to this on the Darwin side. LMK if we can co-ordinate somehow on this.

[jrose-apple]

"Target" is the right term because "target" is the compiler flag (and terminology), and since all three of "build", "host", and "target" are in play for a compiler.

[compnerd]

target is the flag, though the value of the flag is host as that is what the generated builds run on. Quoting from the reference:

--host=host
        The system where built programs and libraries will run.

[jrose-apple]

--target=target
    When building compiler tools: the system for which the tools will create output.

[compnerd]

Correct, when building compiler tools. In fact, even when building the compiler, host/build are the correct term. The "target" is there fore the case that you are cross-compiling a non-cross-compiling compiler. That is, you are building clang on x86_64 for ARM64 which will only build binaries for ARMv7. In such a case, the build is x86_64, the host is aarch64, and the target is armv7. In general, when you are compiling any standard package, the terms are build/host.

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 945917ce4ca3011fa40505a93ffcf995687dcbb1

[compnerd]

@swift-ci please test

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 945917ce4ca3011fa40505a93ffcf995687dcbb1

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - e96e7cc

[compnerd]

@swift-ci please test Linux platform

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - e96e7cc

[compnerd]

Please test with following PRs:
apple/swift-lldb#1829

@swift-ci please test Linux platform

[compnerd]

I'm going to merge this for now. I really want to iterate on this a bit more, the !Darwin bit of that check really doesn't sit well with me.

[vgorloff]

Hello,

When making Cross Compilation for Android on macOS Host I have to provide -sdk flag (-sdk /usr/local/ndk/platforms/android-24/arch-arm).

Without -sdk flag there will be following compile error:

/usr/local/ndk/toolchains/llvm/prebuilt/darwin-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld.gold: error: cannot open crtbegin_dynamic.o: No such file or directory
/usr/local/ndk/toolchains/llvm/prebuilt/darwin-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld.gold: error: cannot open crtend_android.o: No such file or directory

But With -sdk flag (-sdk /usr/local/ndk/platforms/android-24/arch-arm) I am getting another error:

clang: error: no such file or directory: '/usr/local/ndk/platforms/android-24/arch-arm/usr/lib/swift/android/armv7/swiftrt.o'

In this case path to swiftrt.o incorrect: /usr/local/ndk/platforms/android-24/arch-arm/usr/lib/swift/android/armv7/swiftrt.o

Now I am thinking how to solve this error :)

Is -sdk flag can't point anywhere except Swift SDK (which include file swiftrt.o)?

Thank you!

Swift-NoFailures.txt
Swift-WithFailures.txt
Swift-WithoutSDKFlag.txt

[drodriguez]

@vgorloff there's a lot of discussion about what -sdk should mean and should do in the forums thread https://forums.swift.org/t/swift-linux-layout-considerations-aka-linux-is-difficult-lets-go-shopping/27400/2. IIRC, as things are right now, for Android, one might need to pass -sdk pointing to the Swift SDK, and some combination of -Xclang-linker -sysroot -Xclang-linker /foo/bar and -Xcc ... to point to the Android NDK. Look in #26366 for the changes needed for the test suite to run. It might give you a clue.

[vgorloff]

Thank you!

Usage of the flags -Xclang-linker and -Xcc helped to solve issue.