How do we work around SR-15532?

[YOCKOW]

I found the reason of this bug, but I don't know how to fix it.
So, I've created a new topic:

SR-15822 ClangImporter's bug: Why does it import separately clang modules and bridging C headers?

Introduction I did a poor investigation of SR-15586: import Foundation hides declarations (derived from C) in other modules on Linux for these few months. I finally found that it is a bug caused by ClangImporter which is due to how it imports C declarations. Furthermore, the issue would occur on any platforms, even on macOS. (Filed as SR-15822: Existence of modulemap disables declarations in simple C headers in some cases.) How the bug is produced ClangImporter(ClangImporter::Implementation)…