Add the platform conditional and set up other basics for the toolchain.
The ConditionalCompilation tests are updated to match, since otherwise
they seem to trip when building on non-OpenBSD platforms. The
Driver/linker test is updated to ensure lld is passed on this platform.
Note that OpenBSD calls "x86_64" as "amd64", so we use that name for the
architecture instead of trying to alias one to the other, as this makes
things simpler.
Add support for conditional compilation under macCatalyst
Developers can now detect whether they are compiling for macCatalyst at
compile time with:
#if targetEnvironment(macCatalyst)
// Code only compiled under macCatalyst.
#end
For example, for "#if os(simulator)", offer a fixit to change
"os" to "targetEnvironment", instead of offering to change "simulator".
Resolves SR-11037.
Being lazy here just means we don’t validate the entire if
configuration. We need to be able to emit diagnostics even in
condition clauses with indeterminate expressions.
parseBraceItems() has specific logic for pasing conditional compilation blocks.
Withoutout that, decralations in the block cannot be propagated to outside.
For instance:
FOO: #if true
func foo() {}
#endif
foo() // error: use of unresolved identifier 'foo'
