39761b0cf9
Isolate coverage FFI type layouts from their underlying LLVM C++ types I noticed that several of the types used to send coverage information through FFI are not properly isolated from the layout of their corresponding C++ types in the LLVM API. This PR adds more explicitly-defined FFI struct/enum types in `CoverageMappingWrapper.cpp`, so that Rust source files in `rustc_codegen_ssa` and `rustc_codegen_llvm` aren't directly exposed to LLVM C++ types.
Please read the rustc-dev-guide chapter on Backend Agnostic Codegen.