Full build machine paths in panic messages

[webmaster128]

When a Wasm contract panicks, the full file path and line number is visible in the panic message. If a user does not use workspace-optimizer/rust-optimizer, this exposes personal file system infomation

Query failed with (6): rpc error: code = Unknown desc = failed to execute message; message index: 0: Error calling the VM: Error executing Wasm: Wasmer runtime error: RuntimeError: Aborted: panicked at 'Denominator must not be zero', /Users/username/.cargo/registry/src/github.com-AABBCCDDEEAABBCCDD/cosmwasm-std-1.2.6/src/math/decimal.rs:136:17: execute wasm contract failed [!cosm!wasm/wasmd@v_X.Y.Z_/x/wasm/keeper/keeper.go:389] With gas wanted: '100000000' and gas used: 'SOME_VALUE' : unknown request

The contents of the Aborted error is coming from Wasm:

panicked at 'Denominator must not be zero', /Users/username/.cargo/registry/src/github.com-AABBCCDDEEAABBCCDD/cosmwasm-std-1.2.6/src/math/decimal.rs:136:17

The source of this is https://github.com/CosmWasm/cosmwasm/blob/v1.4.1/packages/std/src/panic.rs#L10-L12. If I recall correctly, this used to be a relative path.

It seems like more recent versions of Rust use a line break between location and message.

So to me there are two open questions:

• Can we ensure there are no full file paths in the Wasm file or do we just need to accept that and point to containerized build systems?
• Should we customize how we build up the panic message let full_message = info.to_string();?

[AmitPr]

the --remap-path-prefix rustc flag might be relevant here

[chipshort]

This seems more like something that should be fixed in the Rust compiler.
I did a bit of testing around this and here is what I found:

• Removing the info.to_string() will obviously hide the paths from the panic messages, but it did not remove them from the wasm file. We could probably go through the result of info.to_string() and remove all absolute paths, but it feels a bit like a hack.
• Adding something like RUSTFLAGS="--remap-path-prefix /Users/christoph=/" works, but is obviously very user-specific, so I don't see a way to add it for example to cw-template

[webmaster128]

Yeah, my 2 cents:

• We should communicate it as a known limitation that a user's paths end up in the Wasm if no rust-optimizer/workspace-optimizer is used
• Instead of info.to_string() we can build the panic message manually for stability. E.g. in the past it was only a relative file path. Not it's the full path. And in the latest Rust source code there is a line break between location and message, which we don't really want.
• --remap-path-prefix might be useful inside of rust-optimizer/workspace-optimizer to reduce the size of the Wasm and keep error messages short

[chipshort]

Looks like we cannot build the panic message ourselves, since access to PanicInfo::message is currently not stabilized.