This handles optionality changes and type rewrites in function param and return types and constructor param and failability types.
Resolves rdar://problem/31766010
I had set up the driver to invoke a separate frontend invocation with
the "update code" mode. We sort of did this last release, except we
forked to the swift-update binary instead. This is causing problems with
testing in Xcode.
Instead, let's perform a single compile and add the remap file as an
additional output during normal compiles. The driver, seeing
-update-code, will add -emit-remap-file-path $PATH to the -c frontend
invocation.
rdar://problem/31857580
This adds an adapter class that wraps Clang's lib/Edit
Commit and EditedSource classes for use in the initial
"syntactic" passes. Once the passes have completed,
the resulting source file is then passed to the Swift compiler
fix-it passes.
rdar://problem/30926261
