Zlib issues with source-based coverage

Hi, I wanted to ask here before opening an issue in GH.

I'm trying out source-based coverage with nightly-2020-11-14 (on Windows and WSL).
On Windows, I have LLVM 11 installed, and on WSL I'm relying on llvm-tools-preview.

When trying to use llvm-profdata on Windows, to merge profraw fiies, I get:

warning: default.profraw: Profile uses zlib compression but the profile reader was built without zlib support
warning: arrow/default.profraw: Profile uses zlib compression but the profile reader was built without zlib support
error: No profiles could be merged.

On WSL, I get:

warning: arrow/default.profraw: Failed to uncompress data (zlib)
error: No profiles could be merged.

I can get that both issues are related to LLVM being built without zlib support, but given that i'm getting related zlib errors on both a preinstalled LLVM, and the tools that come with nightly;

Is there a solution to this issue? Or would users who want to try out the coverage have to build LLVM ourselves?

Thanks

I don't have much experience with Rust's coverage tooling, but it might be easier for others to help if you explained exactly what commands you're using :wink: