Rollup merge of #121978 - GuillaumeGomez:dylib-duplicated-path, r=bjorn3

Fix duplicated path in the "not found dylib" error

While working on the gcc backend, I couldn't figure out why I had this error:

```
error: couldn't load codegen backend /checkout/compiler/rustc_codegen_gcc/target/release/librustc_codegen_gcc.so/checkout/compiler/rustc_codegen_gcc/target/release/librustc_codegen_gcc.so: cannot open shared object file: No such file or directory
```

As you can see, the path is duplicated for some reason. After investigating a bit more, I realized that `libloading::Error::LoadLibraryExW` starts with the path of the not found dylib, making it appear twice in our error afterward (because we do render it like this: `{path}{err}`, and since the `err` starts with the path...).

Thanks to `````@bjorn3````` for linking me to https://github.com/rust-lang/rust/pull/121392. :)

1 files changed, 7 insertions, 1 deletions

diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
index 8b48570fbba..0d37c0feb0c 100644
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@@ -1132,7 +1132,13 @@ fn load_dylib(path: &Path, max_attempts: usize) -> Result<libloading::Library, S
             Err(err) => {
                 // Only try to recover from this specific error.
                 if !matches!(err, libloading::Error::LoadLibraryExW { .. }) {
-                    return Err(err.to_string());
+                    let err = format_dlopen_err(&err);
+                    // We include the path of the dylib in the error ourselves, so
+                    // if it's in the error, we strip it.
+                    if let Some(err) = err.strip_prefix(&format!(": {}", path.display())) {
+                        return Err(err.to_string());
+                    }
+                    return Err(err);
                 }
 
                 last_error = Some(err);