embed_migrations! misbehaves in workspaces

[kpcyrd]

Setup

• foo/Cargo.toml <- this is my workspace
• foo/target <- this is the workspace build folder
• foo/bar/Cargo.toml <- my other project
• foo/bar/assets/foo.bin <- an asset
• foo/bar/migrations <- my migrations
• foo/bar/src/main.rs <- this file has embed_migrations!

Versions

• Diesel: 1.3.3
• Diesel migrations: 1.3.0

Problem Description

I have to specify the path differently from what I'm doing in include_bytes!:

embed_migrations!("../bar/migrations");

while I can do the following with assets:

include_bytes!("../assets/foo.bin");

The problem is that the macro panics during cargo package, probably since the path doesn't match anymore during a publish/package, while include_bytes! seems to work.

   = help: message: Error reading migrations: No such file or directory (os error 2)                                               
   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

I couldn't find a way to workaround this yet, changing this to "../migrations" for the release didn't seem to work either.

[kpcyrd]

I was able to work around this with embed_migrations!("migrations"), if I recall correctly I had to provide a path explicitly because foo uses diesel as well and it would pick up foo/migrations from foo/bar otherwise.

[sgrif]

The path given is resolved relative to the CARGO_MANIFEST_DIR environment variable given to us by Cargo, which is the only available information we have. If you believe the value of that environment variable is incorrect in the presence of a workspace, that is a bug in Cargo, not Diesel.