[lld] [ELF] Merge copyLocalSymbols and demoteLocalSymbolsInDiscardedSections (PR #69425)

[Paul Kirth via llvm-commits]

ilovepi wrote:

> > After bisecting it seems like [bbf7b9d](https://github.com/llvm/llvm-project/commit/bbf7b9d805f5773b4fe5bfb69081fe3691a90fb5) is when the issue crops up.
> > Sorry for pinging the wrong PR. Our CI infra hasn't adapted to linkify github PR numbers yet, and I must have copied the wrong PR number. At least I pinged the right person, but still not great. I'll file a separate issue and CC you directly.
> 
> I saw your internal message as well. Do you mean that
> 
> [bbf7b9d](https://github.com/llvm/llvm-project/commit/bbf7b9d805f5773b4fe5bfb69081fe3691a90fb5) ("[ELF] Remove unused setSymbolAndType after #69295. NFC") introduced a regression which is fixed by this patch?
> 

Sorry, I missed this reply. Yes, that was what I meant.

> This ensures for every `Defined` symbol, `d->section->isLive` is true. The "NFC" part from the commit message [bbf7b9d](https://github.com/llvm/llvm-project/commit/bbf7b9d805f5773b4fe5bfb69081fe3691a90fb5) is incorrect.
> 
> Thank you for the zipped reproduce files. I think we miss some coverage for --emit-relocs or -r.

NP. It's what I would want, so I'm happy to do the minimum :)


https://github.com/llvm/llvm-project/pull/69425