[clang] [Serialization] Fix source location data loss during decoding. (PR #145529)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

The design is, the higher 32 bits are used for module file index and the lower bits are used for offsets. Could you give a concrete example why the current implementation is problematic?


https://github.com/llvm/llvm-project/pull/145529