Rollup merge of #134949 - compiler-errors:froms, r=jieyouxu

Convert some `Into` impls into `From` impls

From the [`From`](https://doc.rust-lang.org/std/convert/trait.From.html) docs:

> One should always prefer implementing `From` over [`Into`](https://doc.rust-lang.org/std/convert/trait.Into.html) because implementing `From` automatically provides one with an implementation of [`Into`](https://doc.rust-lang.org/std/convert/trait.Into.html) thanks to the blanket implementation in the standard library.
>
> Only implement [`Into`](https://doc.rust-lang.org/std/convert/trait.Into.html) when targeting a version prior to Rust 1.41 and converting to a type outside the current crate. `From` was not able to do these types of conversions in earlier versions because of Rust’s orphaning rules. See [Into](https://doc.rust-lang.org/std/convert/trait.Into.html) for more details.

Some of these impls are likely from before 1.41, and then some others were probably just mistakes. Building nightly rust is definitely not supported on 1.41, so let's modernize these impls :D

1 files changed, 3 insertions, 3 deletions

diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index 74b6d63365a..a51c4140e17 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -357,9 +357,9 @@ impl From<Cow<'static, str>> for DiagMessage {
 /// subdiagnostic derive refers to typed identifiers that are `DiagMessage`s, so need to be
 /// able to convert between these, as much as they'll be converted back into `DiagMessage`
 /// using `with_subdiagnostic_message` eventually. Don't use this other than for the derive.
-impl Into<SubdiagMessage> for DiagMessage {
-    fn into(self) -> SubdiagMessage {
-        match self {
+impl From<DiagMessage> for SubdiagMessage {
+    fn from(val: DiagMessage) -> Self {
+        match val {
             DiagMessage::Str(s) => SubdiagMessage::Str(s),
             DiagMessage::Translated(s) => SubdiagMessage::Translated(s),
             DiagMessage::FluentIdentifier(id, None) => SubdiagMessage::FluentIdentifier(id),