When we fall back to loading an arm64e module interface during an arm64 build, we want to compile it for the arm64 target so that it is fully compatible with the module that will load it, even though the flags in the file specify the arm64e target. Rewrite the sub-invocation's TargetTriple property in this specific situation. If the two targets differ by more than just the sub-architecture, we will continue to respect the -target flag in the file.
Fixes <rdar://83056545>.
I wasn't aware that arm64e was a thing in open-source, but these two
tests are failing on Apple Silicon both on the main branch and on the
rebranch branch, so I'm disabling it for now.
The failing tests are:
- ModuleInterface/arm64e-fallback.swift
- stdlib/Reflection_objc.swift
If we are building for ARM64 but we try to import a module with only an ARM64e interface, fall back to importing said interface.
This is the reverse of a similar fallback briefly introduced last year, but removed in #31196.
Before this change, we would emit the warning only for swiftmodules; however,
it may be the case that only a swiftinterface (of a different arch) is present
but no swiftmodule is present.
Fixes rdar://problem/50905075.
