From bbd7ce690452f28d459643d97fbae89109cf5808 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matthias=20Kr=C3=BCger?= <matthias.krueger@famsik.de>
Date: Wed, 13 Apr 2022 22:18:28 +0200
Subject: [PATCH] couple of clippy::perf fixes

---
 .../src/debuginfo/metadata/enums/cpp_like.rs                  | 1 -
 compiler/rustc_errors/src/lib.rs                              | 2 +-
 compiler/rustc_expand/src/mbe/macro_parser.rs                 | 2 +-
 compiler/rustc_mir_build/src/thir/pattern/check_match.rs      | 2 +-
 .../src/traits/error_reporting/suggestions.rs                 | 4 ++--
 src/librustdoc/passes/html_tags.rs                            | 2 +-
 6 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs
index 31bb9ed3185..d6e2c8ccdf4 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs
@@ -372,7 +372,6 @@ fn build_union_fields_for_direct_tag_generator<'ll, 'tcx>(
 
     // Build the type node for each field.
     let variant_field_infos: SmallVec<VariantFieldInfo<'ll>> = variant_range
-        .clone()
         .map(|variant_index| {
             let variant_struct_type_di_node = super::build_generator_variant_struct_type_di_node(
                 cx,
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index c927fcb2109..4c1a3931864 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -1208,7 +1208,7 @@ impl HandlerInner {
             (0, 0) => return,
             (0, _) => self.emitter.emit_diagnostic(&Diagnostic::new(
                 Level::Warning,
-                DiagnosticMessage::Str(warnings.to_owned()),
+                DiagnosticMessage::Str(warnings),
             )),
             (_, 0) => {
                 let _ = self.fatal(&errors);
diff --git a/compiler/rustc_expand/src/mbe/macro_parser.rs b/compiler/rustc_expand/src/mbe/macro_parser.rs
index b5f56d7d6dc..cda3d0fd2bf 100644
--- a/compiler/rustc_expand/src/mbe/macro_parser.rs
+++ b/compiler/rustc_expand/src/mbe/macro_parser.rs
@@ -589,7 +589,7 @@ impl TtParser {
                 (_, 0) => {
                     // Dump all possible `next_mps` into `cur_mps` for the next iteration. Then
                     // process the next token.
-                    self.cur_mps.extend(self.next_mps.drain(..));
+                    self.cur_mps.append(&mut self.next_mps);
                     parser.to_mut().bump();
                 }
 
diff --git a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
index 44caa2ac076..58e484e413d 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
@@ -844,7 +844,7 @@ fn non_exhaustive_match<'p, 'tcx>(
                     format!(
                         "{}{}{} => todo!()",
                         comma,
-                        snippet.strip_prefix(",").unwrap_or(&snippet),
+                        snippet.strip_prefix(',').unwrap_or(&snippet),
                         pattern
                     ),
                 ));
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index ead1f0126c4..7485c082f4e 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -2724,9 +2724,9 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 &format!(
                     "consider annotating `{}` with `#[derive({})]`",
                     trait_pred.skip_binder().self_ty(),
-                    diagnostic_name.to_string(),
+                    diagnostic_name,
                 ),
-                format!("#[derive({})]\n", diagnostic_name.to_string()),
+                format!("#[derive({})]\n", diagnostic_name),
                 Applicability::MaybeIncorrect,
             );
         }
diff --git a/src/librustdoc/passes/html_tags.rs b/src/librustdoc/passes/html_tags.rs
index 00e10c6d5a7..a620ffa9878 100644
--- a/src/librustdoc/passes/html_tags.rs
+++ b/src/librustdoc/passes/html_tags.rs
@@ -215,7 +215,7 @@ impl<'a, 'tcx> DocVisitor for InvalidHtmlTagsLinter<'a, 'tcx> {
                     // We don't try to detect stuff `<like, this>` because that's not valid HTML,
                     // and we don't try to detect stuff `<like this>` because that's not valid Rust.
                     if let Some(Some(generics_start)) = (is_open_tag
-                        && dox[..range.end].ends_with(">"))
+                        && dox[..range.end].ends_with('>'))
                     .then(|| extract_path_backwards(&dox, range.start))
                     {
                         let generics_sp = match super::source_span_for_markdown_range(