[SR-14536] Importing FoundationNetworking with -static-stdlib is broken with missing symbols on Linux

[kateinoigakukun]

Previous ID	SR-14536
Radar	rdar://problem/77224218
Original Reporter	@kateinoigakukun
Type	Bug
Status	Resolved
Resolution	Done

Environment

Ubuntu 20.04.2 LTS
Swift version 5.4 (swift-5.4-RELEASE)
Target: x86_64-unknown-linux-gnu

Additional Detail from JIRA

Votes	1
Component/s	Compiler, Foundation
Labels	Bug
Assignee	@kateinoigakukun
Priority	Medium

md5: 7e7c7781d9c433972e4118e0fd2fd9dc

Issue Description:

import FoundationNetworking
_ = URLSession.shared

This code couldn't be built with -static-stdlib due to linking failure on Linux.

This issue was introduced by the use of @_implementationOnly in swift-corelibs-foundation. FoundationNetworking shipped with Swift 5.4 imports CFURLSessionInterface with @_implementationOnly, then FoundationNetworking.swiftmodule doesn't have a dependency declaration of CFURLSessionInterface. So "import FoundationNetworking" doesn't tell the driver to link CFURLSessionInterface and CFURLSessionInterface dependent libraries.

Here is my forum post about this issue several month ago.
Autolinking behavior of @_implementationOnly with static linking

Here is the command line log.

$ swiftc -static-stdlib main.swift -v
/home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/bin/swift-frontend -frontend -c -primary-file main.swift -target x86_64-unknown-linux-gnu -disable-objc-interop -module-name main -o /tmp/main-980558.o -use-static-resource-dir
/home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/bin/swift-autolink-extract /tmp/main-980558.o -o /tmp/main-9e4f94.autolink
/home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/bin/clang -fuse-ld=gold -pie /home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/lib/swift/linux/x86_64/swiftrt.o /tmp/main-980558.o -Xlinker --start-group @/tmp/main-9e4f94.autolink -Xlinker --end-group -L /home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/lib/swift_static/linux @/home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/lib/swift_static/linux/static-stdlib-args.lnk --target=x86_64-unknown-linux-gnu -v -o main
clang version 10.0.0 (git@github.com:apple/llvm-project.git 159d0efd5633014e890836a4227fb867b491eb6b)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Candidate multilib: .;@m64
Selected multilib: .;@m64
 "/usr/bin/ld.gold" -pie -z relro --hash-style=gnu --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o main /usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/Scrt1.o /usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/9/crtbeginS.o -L/home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/lib/swift_static/linux -L/usr/lib/gcc/x86_64-linux-gnu/9 -L/usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/9/../../../../lib64 -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib64 -L/usr/lib/x86_64-linux-gnu/../../lib64 -L/usr/lib/gcc/x86_64-linux-gnu/9/../../.. -L/home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/bin/../lib -L/lib -L/usr/lib /home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/lib/swift/linux/x86_64/swiftrt.o /tmp/main-980558.o --start-group -lFoundationNetworking -lswift_Concurrency -lswiftCore -lFoundation -lswiftGlibc -lm -lpthread -lutil -ldl -lswiftDispatch -ldispatch -lBlocksRuntime -lDispatchStubs -lCoreFoundation -luuid -lswiftSwiftOnoneSupport --end-group -ldl -lpthread -lswiftCore -licui18nswift -licuucswift -licudataswift -lstdc++ -lm -export-dynamic --exclude-libs ALL -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed /usr/lib/gcc/x86_64-linux-gnu/9/crtendS.o /usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/crtn.o
/home/katei/.swiftenv/versions/DEVELOPMENT-SNAPSHOT-2021-04-24-a/usr/lib/swift_static/linux/libFoundationNetworking.a(MultiHandle.swift.o):MultiHandle.swift.o:function $s20FoundationNetworking10URLSessionC12_MultiHandleC03rawE0Svvpfi: error: undefined reference to 'CFURLSessionMultiHandleInit'
... // and many undefined reference errors for CoreFoundation symbols

For now, we can link correctly with extra "-lCFURLSessionInterface -lcurl" options.

[typesanitizer]

@swift-ci create

[kateinoigakukun]

Resolved by #2996