Build failure with SwiftPM package with spaces in directory name on Linux

[cmcgee1024]

When building a SwiftPM package on a path with spaces in it there is a build failure on Linux.

Run this command from a swift-package manager Linux development environment:

swift run swift-build -v --build-system=swiftbuild --package-path=Fixtures/Miscellaneous/Spaces\ Fixture

It's expected that this should pass as it does for similar packages without spaces in the package path.

Instead, we get an error from clang:

info: Link Module Name 1_Module.o (aarch64)
    cd /swiftpm/Fixtures/Miscellaneous/Spaces\ Fixture
    /usr/bin/clang -target aarch64-unknown-linux-gnu -r --sysroot / -O0 -L/swiftpm/Fixtures/Miscellaneous/Spaces\ Fixture/.build/aarch64-unknown-linux-gnu/Intermediates.noindex/EagerLinkingTBDs/Debug-linux -L/swiftpm/Fixtures/Miscellaneous/Spaces\ Fixture/.build/aarch64-unknown-linux-gnu/Products/Debug-linux -L/usr/lib @/swiftpm/Fixtures/Miscellaneous/Spaces\ Fixture/.build/aarch64-unknown-linux-gnu/Intermediates.noindex/Spaces\ Fixture.build/Debug-linux/Module\ Name\ 1_Module.build/Objects-normal/aarch64/Module\ Name\ 1_Module.LinkFileList -nostdlib -rdynamic -o /swiftpm/Fixtures/Miscellaneous/Spaces\ Fixture/.build/aarch64-unknown-linux-gnu/Products/Debug-linux/Module\ Name\ 1_Module.o
error: unknown No such file or directory: '/swiftpm/Fixtures/Miscellaneous/Spaces' []
error: unknown No such file or directory: 'Fixture/.build/aarch64-unknown-linux-gnu/Intermediates.noindex/Spaces' []
error: unknown No such file or directory: 'Fixture.build/Debug-linux/Module' []
error: unknown No such file or directory: 'Name' []
error: unknown No such file or directory: '1_Module.build/Objects-normal/aarch64/Modules/Module_Name_1.o' []
error: unknown No such file or directory: '/swiftpm/Fixtures/Miscellaneous/Spaces' []
error: unknown No such file or directory: 'Fixture/.build/aarch64-unknown-linux-gnu/Intermediates.noindex/Spaces' []
info: Compile main.swift (aarch64)
    cd /swiftpm/Fixtures/Miscellaneous/Spaces\ Fixture

error: unknown No such file or directory: 'Fixture.build/Debug-linux/Module' []
error: unknown No such file or directory: 'Name' []
error: unknown No such file or directory: '1_Module.build/Objects-normal/aarch64/Foo.o' []
info: clang: error: no such file or directory: '/swiftpm/Fixtures/Miscellaneous/Spaces'
clang: error: no such file or directory: 'Fixture/.build/aarch64-unknown-linux-gnu/Intermediates.noindex/Spaces'
clang: error: no such file or directory: 'Fixture.build/Debug-linux/Module'
clang: error: no such file or directory: 'Name'
clang: error: no such file or directory: '1_Module.build/Objects-normal/aarch64/Modules/Module_Name_1.o'
clang: error: no such file or directory: '/swiftpm/Fixtures/Miscellaneous/Spaces'
clang: error: no such file or directory: 'Fixture/.build/aarch64-unknown-linux-gnu/Intermediates.noindex/Spaces'
clang: error: no such file or directory: 'Fixture.build/Debug-linux/Module'
clang: error: no such file or directory: 'Name'
clang: error: no such file or directory: '1_Module.build/Objects-normal/aarch64/Foo.o'
error: Build failed

[cmcgee1024]

This appears to be caused by the way that the link file list is being set up for clang. It's interpreting the space as a file name delimiter.

[cmcgee1024]

Clang on linux expects shell escaping for each line of the file list file. See the following section of code where the file list file is generated:

swift-build/Sources/SWBCore/SpecImplementations/Tools/LinkerTools.swift

Line 353 in d8be8e6

// ld64 reads lines from the file using fgets, without doing any other processing.

This comment:

// ld64 reads lines from the file using fgets, without doing any other processing.

It only applies to a specific linker, ld64. If clang, or other linkers are interpreting this file then some might have other conventions. For example, clang will directly interpret the list with @, but if the file is sent to the linker via an -Xlinker flag then the linker will read the file. It is currently unknown what binutils ld, and lld-link.exe will do in these cases.