notifications: log directly on metadata upgrades that remove toolchains

Author: djc

src/config.rs

@@ -8,7 +8,7 @@ use anyhow::{Context, Result, anyhow, bail};
 use serde::Deserialize;
 use thiserror::Error as ThisError;
 use tokio_stream::StreamExt;
-use tracing::{debug, error, info, trace};
+use tracing::{debug, error, info, trace, warn};
 
 use crate::dist::AutoInstallMode;
 use crate::{
@@ -455,7 +455,9 @@ impl<'a> Cfg<'a> {
         match current_version {
             MetadataVersion::V2 => {
                 // The toolchain installation format changed. Just delete them all.
-                (self.notify_handler)(Notification::UpgradeRemovesToolchains);
+                warn!(
+                    "this upgrade will remove all existing toolchains; you will need to reinstall them"
+                );
 
                 let dirs = utils::read_dir("toolchains", &self.toolchains_dir)?;
                 for dir in dirs {

src/notifications.rs

@@ -25,7 +25,6 @@ pub(crate) enum Notification<'a> {
     /// member, but the notification callback is already narrowed to
     /// utils::notifications by the time tar unpacking is called.
     SetDefaultBufferSize(usize),
-    UpgradeRemovesToolchains,
     /// Both `rust-toolchain` and `rust-toolchain.toml` exist within a directory
     DuplicateToolchainFile {
         rust_toolchain: &'a Path,
@@ -45,7 +44,7 @@ impl Notification<'_> {
             | DownloadDataReceived(_, _)
             | DownloadFinished(_)
             | DownloadFailed(_) => NotificationLevel::Debug,
-            UpgradeRemovesToolchains | DuplicateToolchainFile { .. } => NotificationLevel::Warn,
+            DuplicateToolchainFile { .. } => NotificationLevel::Warn,
         }
     }
 }
@@ -73,10 +72,6 @@ impl Display for Notification<'_> {
             DownloadDataReceived(data, _) => write!(f, "received some data of size {}", data.len()),
             DownloadFinished(_) => write!(f, "download finished"),
             DownloadFailed(_) => write!(f, "download failed"),
-            UpgradeRemovesToolchains => write!(
-                f,
-                "this upgrade will remove all existing toolchains. you will need to reinstall them"
-            ),
             DuplicateToolchainFile {
                 rust_toolchain,
                 rust_toolchain_toml,