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?


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:

@nevi-me - Please check out the updated documentation, specifically, the new section:

There were some updates made recently to make sure all of the LLVM tools required for coverage reports are included, and depending on your version, one of those tools may have not been included. It looks like you are using a version that is either outdated, or misconfigured. I believe the zlib issue should go away if you use the tools per the new instructions.

Also, there have been some bug fixes recently, so you may want to update your version of nightly.

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