`weakly_canonical` will resolve as much as possible in the path, and not
return an error if it can't resolve everything (for example due to a
non existant file). In any case in case of problems with the file we
will see an error when actually using the resolved path.
This tunes down some unhelpful log messages.
File hashing is now done internally in `SwiftFileInterception` (and
exported as a `getHashOfRealFile` function for future use in linkage
awareness), and using a per-process in-memory cache. The persistent
caching of paths is removed, so the solution is now robust against input
file changes during the build.
For the same reason, the hash to artifact mapping have the symlinks
reversed now. The artifacts themselves are stored using the hash as
filenames, and the original paths of the artifacts are reacreated in the
scratch dir with symlinks mostly for debugging purposes (to understand
what artifact each hash corresponds to, and to follow what was built by
the extractor).
On macOS `$(CC)` points to a wrapper that requires `DEVELOPER_DIR` to be
set in the environment. Using `clang` is slightly less generic, but
that's our default any way. Even if we do set a different clang version
somewhere, the selected version of GCC would not change, and the test
is targeting that.
Previous to this patch the code contained a workaround for the standard
defect
https://cplusplus.github.io/LWG/issue3657
where `std::filesystem::path` did not have a `std::hash` implementation.
This patch allows compiling against versions of the STL that contain the
fix to the above issue. This is done by running the compiler against
code defining `std::hash<std::filesystem::path>`: if compilation
succeeds, it means the fix is not there and we need to use the
workaround, contained in `PathHash.h.workaround`. Otherwise, the fix is
there and we use `PathHash.h.fixed` instead, which only includes the
standard headers included by `PathHash.h.workaround`, so that one is a
drop-in replacement of the other.
With the change to `std::filesystem` some path concatenations were
translated to appending, which is not the same. In case rhs is absolute
`lhs / rhs == rhs`, while concatenating treats `rhs` as if it was
relative. The same behaviour can be obtained in `std::filesystem` by
using `lhs / rhs.relative_path()`.
This replaces usages of `llvm::fs` and string manipulation with
`std::filesystem`, also replacing `std::string` with
`std::filesystem::path` where it made sense.
Moreover MD5 hashing used in macOS file remapping was replaced by
SHA256 hashing using a small header-only SHA256 C++ library with an
MIT license, https://github.com/okdshin/PicoSHA2.
File contents hashing was relocated to the newly created `file` library
for later planned reuse.
