Compile-time errors are only visible in the first project of a VSCode workspace

Compile-time errors are only visible in the first project of a VSCode workspace.

Steps for reproducing the issue:

1. Create Rust projects and a VSCode workspace for them:

   mkdir test
   cd test
   cargo new --lib lib1
   echo compile-time error here >> lib1/src/lib.rs
   cargo new --lib lib2
   echo compile-time error here >> lib2/src/lib.rs
   cargo new --lib lib3
   echo compile-time error here >> lib3/src/lib.rs
   cat > test.code-workspace <<END
   {
     "folders": [
       { "path": "lib1" },
       { "path": "lib2" },
       { "path": "lib3" }
     ],
     "settings": { "rust-analyzer.linkedProjects": [ "./Cargo.toml" ] }
   }
   END
   

2. Open test.code-workspace in VSCode (with rust-analyzer extension installed).
3. Open lib1/src/lib.rs, lib2/src/lib.rs and lib3/src/lib.rs by double-clicking them in VSCode explorer.
4. Compile-time error is shown only for lib1/src/lib.rs, not for lib2/src/lib.rs or lib3/src/lib.rs.

Environment

• macOS Ventura 13.6 @ Apple Silicon M2
• VSCodium 1.83.0, release 23277
• rust-analyzer extension 0.3.1689
• rust-analyzer 1.73.0 (cc66ad46 2023-10-03)

Reproduce the issue with the provided test.code-workspace and the three lib.rs files, checking diagnostics in each project. Start by examining how rust-analyzer handles the linkedProjects workspace setting; done means compile-time errors appear for lib1, lib2, and lib3.