Failure to produce offline documentation if you consume C++ libraries via Swift C++/Interop

[apple]

Failure to produce offline documentation if you consume C++ libraries via Swift C++/Interop

[heckj]

Jumping in sideways a bit here - I haven't done the internal analysis, but I suspect this is related to apple/swift-package-manager#6162 (and in turn #50), where Docc is relying in swift package manager to "provide all the relevant symbols" - but there's some edge cases where its unable to provide them.

The gist in my debugging found that there we assumptions and potentially multiple paths in SwiftPM for getting the symbols, and the paths diverged when compiling swift vs. using libraries. There were some comments in SwiftPM source that talked to "combining paths down the road", which I suspect is fundamentally part of this issue. If I read the code right (no promises there), the "quick path" for libraries expected relevant module caches to have been populated already from all the various libraries, and process which didn't hold up when using the static library from a binaryTarget. I suspect C++ interop is in the same relative boat, although there may be more blocks - if they're C++ symbols, I've no idea if those have representations yet in the symbol graphs.

[migueldeicaza]

While running swift package dump-symbol-graph works with the attached sample, which does not do much of any C++ at all, the same command breaks with my actual codebase that uses C++, like this:

Building for debugging...
[2/2] Compiling plugin Swift-DocC Preview
Build complete! (6.61s)
-- Emitting symbol graph for SwiftNavigation
<module-includes>:1:9: note: in file included from <module-includes>:1:
#import "/Users/miguel/cvs/SwiftNavigation/Sources/CRecast/include/Bridging.h"
        ^