cargo-doc overwrites similarly-named library target with binary target

[Aehmlo]

Consider the following Cargo.toml (some contents are redundant, but they're there to be explicit).

[package]
name = "foo"
version = "0.1.0"
authors = ["Some Body <nobody@nowhere.org>"]

[lib]
name = "foo_bar"
path = "src/lib.rs"
doc = true

[[bin]]
name = "foo-bar"
path = "src/main.rs"
doc = true

When cargo doc is run, the resulting documentation has one entry for the crate foo_bar, displaying the documentation extracted from the binary target foo-bar. I presume this has something to do with the the historical "hyphens are underscores in crate names," and I recognize it's quite the edge case, but it just took me about half an hour to figure this out just now and I figured I'd say something about it anyway. It'd be nice if the result would be something more like foo_bar and foo-bar docs, or even something like foo_bar_lib and foo_bar_bin.

I'm using cargo 1.26.0 and rustdoc 1.26.0, though I first noticed the issue using cargo nightly (2018-05-07).

[aidanhs]

This also happens with crates, e.g. if you have a binary called libc and depend on the libc crate:

Cargo.toml:

[package]
name = "x"
version = "0.1.0"
authors = []

[dependencies]
libc = "*"

src/bin/libc.rs

fn main() {}

src/main.rs (unnecessary, but cargo doc --open won't work without it)

fn main() {}

Running cargo doc --open will show you docs, and the libc documentation will show a blank page.

[epage]

Thanks to #6998, this is mostly resolved

arning: output filename collision.
The bin target `foo-bar` in package `foo v0.1.0 (/home/epage/src/personal/dump/foo)` has the same output filename as the lib target `foo_bar` in package `foo v0.1.0 (/home/epage/src/personal
/dump/foo)`.
Colliding filename is: /home/epage/src/personal/dump/foo/target/doc/foo_bar/index.html
The output filenames should be unique.
This is a known bug where multiple crates with the same name use
the same path; see <https://github.com/rust-lang/cargo/issues/6313>.
If this looks unexpected, it may be a bug in Cargo. Please file a bug report at
https://github.com/rust-lang/cargo/issues/ with as much information as you
can provide.
cargo 1.73.0 (9c4383fb5 2023-08-26) running on `x86_64-unknown-linux-gnu` target `x86_64-unknown-linux-gnu`
First unit: Unit { pkg: Package { id: PackageId { name: "foo", version: "0.1.0", source: "/home/epage/src/personal/dump/foo" }, ..: ".." }, target: TargetInner { name: "foo-bar", doc: true,
..: with_path("/home/epage/src/personal/dump/foo/src/main.rs", Edition2015) }, profile: Profile { ..: default_dev() }, kind: Host, mode: Doc { deps: true }, features: [], artifact: false, ar
tifact_target_for_features: None, is_std: false, dep_hash: 17975679418527223829 }
Second unit: Unit { pkg: Package { id: PackageId { name: "foo", version: "0.1.0", source: "/home/epage/src/personal/dump/foo" }, ..: ".." }, target: TargetInner { ..: lib_target("foo_bar", [
"lib"], "/home/epage/src/personal/dump/foo/src/lib.rs", Edition2015) }, profile: Profile { ..: default_dev() }, kind: Host, mode: Doc { deps: true }, features: [], artifact: false, artifact_
target_for_features: None, is_std: false, dep_hash: 2202906307356721367 }
 Documenting foo v0.1.0 (/home/epage/src/personal/dump/foo)
    Finished dev [unoptimized + debuginfo] target(s) in 0.28s

See #6313 for any next steps on where this might go.