We are trying to migrate from gold to lld, and we found that when building with thinlto, lld does not de-duplicate .debug_types. De-duplication is successful with monolithic lto. Repro: clang -flto=thin -fdebug-types-section -fuse-ld=lld -Wl,-plugin-opt=-generate-type-units
If we set ignoreComdats=false for lto builds, then the de-duplication is successful again. Looking at the thinlto code, it looks like there is no comdat folding at thinlto time.
For more context, see https://reviews.llvm.org/D62884