`docs.rs` cannot build `datafusion-proto` crate

[andygrove]

Describe the bug

[INFO] [stderr]    Compiling datafusion-proto v12.0.0 (/opt/rustwide/workdir)
[INFO] [stderr] error: failed to run custom build command for `datafusion-proto v12.0.0 (/opt/rustwide/workdir)`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `/opt/rustwide/target/debug/build/datafusion-proto-4369f54fa6f25371/build-script-build` (exit status: 1)
[INFO] [stderr]   --- stdout
[INFO] [stderr]   cargo:rerun-if-env-changed=FORCE_REBUILD
[INFO] [stderr]   cargo:rerun-if-changed=proto/datafusion.proto
[INFO] [stderr]   Running: "/usr/bin/protoc" "--include_imports" "--include_source_info" "-o" "/tmp/prost-buildQPnxTC/prost-descriptor-set" "-I" "proto" "proto/datafusion.proto"
[INFO] [stderr] 
[INFO] [stderr]   --- stderr
[INFO] [stderr]   Error: "protobuf compilation failed: Read-only file system (os error 30)"

To Reproduce
Steps to reproduce the behavior:

Expected behavior
A clear and concise description of what you expected to happen.

Additional context
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[andygrove]

@avantgardnerio @alamb This is one side-effect of the recent change to generate protobuf into the src directory. I don't have a strong opinion on how much of an issue this is, although it would be nice to have docs.

[avantgardnerio]

@andygrove do you have a link to the build in question? The error message isn't sufficient in and of itself, but I feel like this is fixable.

[andygrove]

@andygrove do you have a link to the build in question? The error message isn't sufficient in and of itself, but I feel like this is fixable.

https://docs.rs/crate/datafusion-proto/12.0.0

[avantgardnerio]

Got it, so https://docs.rs/crate/datafusion-proto/12.0.0/builds/630103

[avantgardnerio]

This looks broken because the source directory is closed to a readonly file system https://docs.rs/about/builds#read-only-directories

But should be fixable using conditional compilation flags https://docs.rs/about/builds#cross-compiling

[tustvold]

Docs builds are still failing