Hi, Rintaro. That’s a clever solution; it would mean we wouldn’t be blocked by talking to the Clang folks about making module map search paths SDKROOT-relative. That said, the VFS is a fairly, well, hacky piece of Clang, and I’m not sure we’d want to add a new dependency on it. Ben, Daniel, what do you think?
Jordan > On May 21, 2016, at 05:36, rintaro ishizaki via swift-dev > <swift-dev@swift.org> wrote: > > Hi all, > > Recently, a couple of PR are posted regarding > glibc.modulemap in cross-compiling environment. > > https://github.com/apple/swift/pull/2473 > <https://github.com/apple/swift/pull/2473> > https://github.com/apple/swift/pull/2486 > <https://github.com/apple/swift/pull/2486> > > The problem is that glibc.modulemap contains hardcoded SDKROOT in it. > To resolve that, how about using virtual file system feature in Clang? > > I mean, prepare YAML like this: > > { > "use-external-names": false, > "roots": [ > { > "type": "file", > "name": "${SYSROOT}/usr/include/module.map", > "external-contents": "${RSRC}/${platform}/${arch}/glibc.modulemap" > } > ] > } > > Then, invoke Clang with -ivfsoverlay argument. > > Of course, we have to dynamically create YAML based on -sdk and -target > argument of the Swift compiler. > Luckily, Clang provides convenient YAML builder for this: > http://clang.llvm.org/doxygen/classclang_1_1vfs_1_1YAMLVFSWriter.html > <http://clang.llvm.org/doxygen/classclang_1_1vfs_1_1YAMLVFSWriter.html> > It's easy and trivial work to build that dynamically. > > Using this feature, glibc.modulemap can be rather simple. > No need to specify absolute path. > It can be simple as /usr/include/module.map in Darwin platforms: > > module ctype { > header "ctype.h" > export * > } > > And, it makes easy to import Clang builtin headers like "limits.h". > > Here is the PoC code: > https://github.com/apple/swift/compare/master...rintaro:clang-vfsoverlay > <https://github.com/apple/swift/compare/master...rintaro:clang-vfsoverlay> > It works, and passes all Swift test suite. > > Current my concerns are: > * The VFS overlay is the right way in the first place? > * Since I'm a very newbie in C++ programming, I'm not sure I'm doing right > thing in the code. > > Any thought? > > _______________________________________________ > swift-dev mailing list > swift-dev@swift.org > https://lists.swift.org/mailman/listinfo/swift-dev
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