Use single-char patter on {ends,starts}_with and remove clone on copy type.

These were introduced since I last fixed most of these occurences. (clippy::clone_on_copy, clippy::single_char_pattern)

Author: matthiaskrgr

src/librustc_errors/registry.rs

@@ -27,6 +27,6 @@ impl Registry {
         if !self.long_descriptions.contains_key(code) {
             return Err(InvalidErrorCode);
         }
-        Ok(self.long_descriptions.get(code).unwrap().clone())
+        Ok(*self.long_descriptions.get(code).unwrap())
     }
 }

src/librustc_resolve/late/diagnostics.rs

@@ -1086,7 +1086,7 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
                     for param in params {
                         if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(param.span)
                         {
-                            if snippet.starts_with("&") && !snippet.starts_with("&'") {
+                            if snippet.starts_with('&') && !snippet.starts_with("&'") {
                                 introduce_suggestion
                                     .push((param.span, format!("&'a {}", &snippet[1..])));
                             } else if snippet.starts_with("&'_ ") {
@@ -1118,7 +1118,7 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
                 (1, Some(name), Some("'_")) => {
                     suggest_existing(err, name.to_string());
                 }
-                (1, Some(name), Some(snippet)) if !snippet.ends_with(">") => {
+                (1, Some(name), Some(snippet)) if !snippet.ends_with('>') => {
                     suggest_existing(err, format!("{}<{}>", snippet, name));
                 }
                 (0, _, Some("&")) => {
@@ -1127,7 +1127,7 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
                 (0, _, Some("'_")) => {
                     suggest_new(err, "'a");
                 }
-                (0, _, Some(snippet)) if !snippet.ends_with(">") => {
+                (0, _, Some(snippet)) if !snippet.ends_with('>') => {
                     suggest_new(err, &format!("{}<'a>", snippet));
                 }
                 _ => {