[clang] [clang] Propagate definition data to all redecls (PR #170090)

[Jonas Hahnfeld via cfe-commits]

hahnjo wrote:

> Apparently, compiling our code with optimized clang binary was not enough. When running Clang built with assertions, I found some cases where this commit causes crashes. I'll prepare a test case, but maybe the assertion failure along with the crash stack will tell you something already:

As far as I can tell, that's the same issue described in https://github.com/llvm/llvm-project/pull/133057#issuecomment-3610498616. Either one of the approaches in https://github.com/llvm/llvm-project/pull/133057#issuecomment-3611325017 or https://github.com/llvm/llvm-project/pull/170823 should address this. No need to prepare a test case, as far as I can tell.

https://github.com/llvm/llvm-project/pull/170090