[PATCH] D42680: [ThinLTO] Ignore -fthinlto-index= for non-ThinLTO files

[Teresa Johnson via Phabricator via cfe-commits]

tejohnson added a comment.

In https://reviews.llvm.org/D42680#991938, @pcc wrote:

> This doesn't seem right to me. In a mixed full/thin LTO link the full LTO module would be compiled during the indexing phase. We don't want to compile it again in the backend as it could lead at best to duplicate symbol errors and at worst to miscompiles of `llvm.type.*` intrinsic calls.


Good point. The build system will presumably expect an output file to be generated, so probably just compile an "empty" Module in this case?


https://reviews.llvm.org/D42680