feat(dist): refine suggestions regarding manifest checksum mismatches

src/config.rs

@@ -940,7 +940,7 @@ impl<'a> Cfg<'a> {
     }
 }
 
-fn dist_root_server(process: &Process) -> Cow<'static, str> {
+pub(crate) fn dist_root_server(process: &Process) -> Cow<'static, str> {
     process
         .var("RUSTUP_DIST_SERVER")
         .ok()

src/dist/mod.rs

@@ -10,10 +10,13 @@ use once_cell::sync::Lazy;
 use regex::Regex;
 use serde::{Deserialize, Serialize};
 use thiserror::Error as ThisError;
-use tracing::info;
+use tracing::{info, warn};
 
 use crate::{
-    config::Cfg, currentprocess::Process, errors::RustupError, toolchain::ToolchainName,
+    config::{dist_root_server, Cfg},
+    currentprocess::Process,
+    errors::RustupError,
+    toolchain::ToolchainName,
     utils::utils,
 };
 
@@ -1166,9 +1169,23 @@ pub(crate) async fn dl_v2_manifest(
             Ok(Some((manifest, manifest_hash)))
         }
         Err(any) => {
-            if let Some(RustupError::ChecksumFailed { .. }) = any.downcast_ref::<RustupError>() {
-                // Checksum failed - issue warning to try again later
-                info!("update not yet available, sorry! try again later")
+            if let Some(err @ RustupError::ChecksumFailed { .. }) =
+                any.downcast_ref::<RustupError>()
+            {
+                // Manifest checksum mismatched.
+                warn!("{err}");
+
+                let server = dist_root_server(download.process);
+                if server == DEFAULT_DIST_SERVER {
+                    // This might indicate a transient state during an update
+                    // on the official release server
+                    // (see <https://github.com/rust-lang/rustup/issues/3390>)
+                    info!("this is likely due to an ongoing update of the official release server, please try again later");
+                } else {
+                    // This could also indicate a misconfiguration of a third-party release server
+                    // (see <https://github.com/rust-lang/rustup/issues/3885>).
+                    info!("this might indicate an issue with the third-party release server `{server}`");
+                }
             }
             Err(any)
         }

tests/suite/cli_v2.rs

@@ -360,7 +360,7 @@ async fn bad_sha_on_manifest() {
     cx.config
         .expect_err(
             &["rustup", "default", "nightly"],
-            "update not yet available",
+            "info: this might indicate an issue with the third-party release server",
         )
         .await;
 }