cargo tree does not report a proc-macro duplicate in a workspace

[ehuss]

Problem

With resolver = "2", and a workspace with a proc-macro, duplicates of a shared dependency are not displayed in cargo tree in some situations.

Steps

The following cargo test demonstrates the problem.

#[cargo_test]
fn internal_default_features_twice() {
    // Test for new resolver where a shared dependency only differs in whether
    // or not it has the "default" feature enabled.
    // There was an issue where `cargo tree` was incorrectly merging it in the
    // output.
    let p = project()
        .file(
            "Cargo.toml",
            r#"
                [workspace]
                resolver = "2"
                members = ["foo", "foo_derive", "shared"]
            "#,
        )
        .file(
            "foo/Cargo.toml",
            r#"
                [package]
                name = "foo"
                version = "0.1.0"

                [dependencies]
                shared = {path="../shared", default-features=false}

                [features]
                default = ["std"]
                std = ["shared/std"]
            "#,
        )
        .file("foo/src/lib.rs", "")
        .file(
            "foo_derive/Cargo.toml",
            r#"
                [package]
                name = "foo_derive"
                version = "0.1.0"

                [lib]
                proc-macro = true

                [dependencies]
                foo = {path="../foo"}
            "#,
        )
        .file("foo_derive/src/lib.rs", "")
        .file(
            "shared/Cargo.toml",
            r#"
                [package]
                name = "shared"
                version = "0.1.0"

                [features]
                default = ["std"]
                std = []
            "#,
        )
        .file("shared/src/lib.rs", "")
        .build();

    p.cargo("tree -f")
        .arg("{p} ({f})")
        .with_stdout(
            "\
foo [..] (default,std)
└── shared [..] (default,std)

foo_derive (proc-macro) [..] ()
└── foo [..] (default,std)
    └── shared [..] (std)

shared [..] (default,std)
",
        )
        .run();
}

The problem is that cargo currently shows:

foo_derive v0.1.0 (proc-macro) ()
└── foo v0.1.0 (default,std) (*)

Indicating that the proc-macro is using the same foo. However it is not, foo is built twice. Once as a workspace root (with a dependency on shared with default,std features), and once as a proc-macro dependency (with a dependency on shared with only the std feature).

Possible Solution(s)

No response

Notes

No response

Version

cargo 1.62.0-nightly (f63f23ff1 2022-04-28)

[Muscraft]

This might be related to #10645