Rollup merge of rust-lang#90544 - ehuss:demote-locator-warn, r=petrochenkov

Demote metadata load warning to "info".

There is a warn log message for whenever the crate loader fails to load metadata from a candidate file. I think this warning is too aggressive, as there are several situations where metadata information might not be found in a candidate file, which is normal. Also, this warning is somewhat confusing, and non-actionable in most cases for a user (most users will not know what it means).

If the crate loader ultimately does not find a valid crate, then an error will be reported (and hopefully rust-lang#88368 will improve that error message).

If a rustc developer wants to debug a loader problem, they can still use `RUSTC_LOG=rustc_metadata=debug` and get the details.

There is more discussion of this particular warning at rust-lang#89795 (comment).

Fixes rust-lang#90525

Author: matthiaskrgr

compiler/rustc_metadata/src/locator.rs

@@ -236,7 +236,7 @@ use std::fmt::Write as _;
 use std::io::{Read, Result as IoResult, Write};
 use std::path::{Path, PathBuf};
 use std::{cmp, fmt, fs};
-use tracing::{debug, info, warn};
+use tracing::{debug, info};
 
 #[derive(Clone)]
 crate struct CrateLocator<'a> {
@@ -549,7 +549,7 @@ impl<'a> CrateLocator<'a> {
                         }
                     }
                     Err(err) => {
-                        warn!("no metadata found: {}", err);
+                        info!("no metadata found: {}", err);
                         continue;
                     }
                 };