PE/COFF does not permit weak linking semantics. This means that the
expression `&symbol == NULL` is tautologically false. In order to
support this semantic, the symbol needs to be dynamically looked up at
runtime. Since the ObjC runtime is not in use on Windows currently,
just ignore this for the time being. Silences a warning from clang
about the tautological comparison.
Also have swift-reflection-test check if the symbol exists. This allows swift-reflection-test to work with older Remote Mirror dylibs that don't have it.
rdar://problem/50030805
This was used for the swift-reflection-test tool. Instead of using fat
binaries, use the target binary itself. This simplifies the build logic
as well as paves the road to sub-builds for each target rather than a
monolithic build as we have today.
Originally, the swift-reflection-test was a host tool that linked
against the target libraries since it was testing the target layout.
Now that the tool has been split into a host and target component
(5ea5bb06a3) and we have target and host
libraries that we can link against appropriately, we do not need to link
against the FAT binary. Since there was exactly one use of this
functionality, switching that from fat linking to regular linking allows
us to remove this functionality entirely. Switch to regular linking and
remove the option.
Recent Swift uses 2 as the is-Swift bit when running on newer versions, and 1 on older versions. Since it's difficult or impossible to know what we'll be running on at build time, make the selection at runtime.
This adds an explicit version of the SwiftRemoteMirror library for use
in the tools that comprise the toolchain. This is a separate build from
the target specific builds of the library even though we may be building
the runtime for the (same) host.
If one thinks about it, swift's build has two sections: a runtime or target
section (i.e. ./stdlib) and a host section (everything
else). swift-reflection-test is an abberation from that pattern since it is
built for target platforms but is in the section of host tools.
In this commit, I move it into ./stdlib. Beyond being a bitter location
conceptually this will additionally allow me to avoid a dependency cycle in
between the compiler and the stdlib build.
After this, there is only one more target in the compiler code: swift-lang. From
talking with Xi Ge, we can move that into its own separate project as a
package. Once that is done, I will not have any more cycles.
