This allows automatic differentiation of concrete calls to math functions operating on `Double`. Such calls were not differentiable because the concrete math functions were imported from C, not the generic ones defined in Swift. The fix is to define derivatives for these C functions. `test/AutoDiff/stdlib/tgmath_derivatives.swift.gyb` was modified to test the new functions.
This change adds support for WASI in stdlib tests. Some tests that expect a crash to happen had to be disabled, since there's currently no way to observe such crash from a WASI host.
This replaces swiftMSVCRT with swiftCRT. The big difference here is
that the `visualc` module is no longer imported nor exported. The
`visualc` module remains in use for a singular test wrt availability,
but this should effectively remove the need for the `visualc` module.
The difference between the MSVCRT and ucrt module was not well
understood by most. MSVCRT provided ucrt AND visualc, combining pieces
of the old MSVCRT and the newer ucrt. The ucrt module is what you
really wanted most of the time, however, would need to use MSVCRT for
the convenience aliases for type-generic math and the deprecated math
constants.
Unfortunately, we cannot shadow the `ucrt` module and create a Swift SDK
overlay for ucrt as that seems to result in circular dependencies when
processing the `_Concurrency` module.
Although this makes using the C library easier for most people, it has a
more important subtle change: it cleaves the dependency on visualc.
This means that this enables use of Swift without Visual Studio for the
singular purpose of providing 3 header files. Additionally, it removes
the need for the installation of 2 of the 4 support files. This greatly
simplifies the deployment process on Windows.
Clean up a few general patterns that are now obviated by canImport
This aligns more generally with the cleanup that the Swift Package
Manager has already done in their automated XCTest-plumbing tool in
apple/swift-package-manager#1826.
New files were added in #30875 which did not include os(OpenBSD), so add
this.
add_swift_target_library in AddSwiftStdlib subsequently required
modification. _add_target_variant_link_flags likely needs modification as
well, but this is better suited to a separate PR.
