llvm-project

d9b81202 - [lld/COFF] Fix -start-lib / -end-lib more after reviews.llvm.org/D116434 (#124294)

[lld/COFF] Fix -start-lib / -end-lib more after reviews.llvm.org/D116434 (#124294) This is a follow-up to #120452 in a way. Since lld/COFF does not yet insert all defined in an obj file before all undefineds (ELF and MachO do this, see #67445 and things linked from there), it's possible that: 1. We add an obj file a.obj 2. a.obj contains an undefined that's in b.obj, causing b.obj to be added 3. b.obj contains an undefined that's in a part of a.obj that's not yet in the symbol table, causing a recursive load of a.obj, which adds the symbols in there twice, leading to duplicate symbol errors. For normal archives, `ArchiveFile::addMember()` has a `seen` check to prevent this. For start-lib lazy objects, we can just check if the archive is still lazy at the recursive call. This bug is similar to issue #59162. (Eventually, we'll probably want to do what the MachO and ELF ports do.) Includes a test that caused duplicate symbol diagnostics before this code change.