Identical target names within different crates in a workspace have colliding docs paths

[vlovich]

Problem

The lib target the_engine in package library v0.1.0 (/home/runner/work/the-engine/the-engine/library) has the same output filename as the bin target the-engine in package executable v0.1.0 (/home/runner/work/the-engine/the-engine/binary).
Colliding filename is: /home/runner/work/the-engine/the-engine/target/doc/the_engine/index.html

While this directs to #6313, it looks to actually just be a Cargo bug since it's weird to require separate crates within a workspace to guarantee unique target names. Indeed, if I want libthe-engine.so and an executable the-engine (or the-engine.dll and the-engine.exe on Windows), it seems reasonable I should be able to do so within the same workspace. It looks like the root of the problem is that cargo doc uses the name of the workspace rather than also including the name of the crate.

Steps

1. Create a workspace with a lib and a bin crate
2. Give the crates separate names but add a [[bin]] to the bin crate that aliases the name of the lib crate
3. cargo doc --all

Possible Solution(s)

No response

Notes

The reason I think this is a bug is because a crate within a workspace should not have too much of an observable difference in behavior from a crate outside the workspace that does the same thing. Yet in this case the lack of namespacing by crate by cargo doc within a workspace results in a difference of behavior that you wouldn't observe with a crate hosted in its own repository.

Version

This is what I have running locally but in CI it's 1.84.1 running on Ubuntu 22.04

cargo 1.84.0 (66221abde 2024-11-19)
release: 1.84.0
commit-hash: 66221abdeca2002d318fde6efff516aab091df0e
commit-date: 2024-11-19
host: x86_64-unknown-linux-gnu
libgit2: 1.8.1 (sys:0.19.0 vendored)
libcurl: 8.9.0-DEV (sys:0.4.74+curl-8.9.0 vendored ssl:OpenSSL/1.1.1w)
ssl: OpenSSL 1.1.1w  11 Sep 2023
os: Arch Linux Rolling Release [64-bit]

[weihanglo]

To help us understand the actual problem without misinterpreting it, would you mind writing a simple shell script for creating a minimal reproducible example?

[ehuss]

I believe this is covered in #6313, in the point "rustdoc in a workspace where multiple crates have the same name." We currently don't have the ability to organize rustdoc's directories in such a way to deconflict them. That will require design and implementation work in rustdoc to be able to pass in the mapping information it needs to discover the proper directories.