Rollup merge of #93634 - matthiaskrgr:clippy_complexity_jan_2022, r=oli-obk

compiler: clippy::complexity fixes

useless_format
map_flatten
useless_conversion
needless_bool
filter_next
clone_on_copy
needless_option_as_deref

2 files changed, 4 insertions, 5 deletions

diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index 4b85531557c..9a2fb3b86e2 100644
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -1362,8 +1362,7 @@ impl<'a> Resolver<'a> {
                     .filter(|(_, module)| {
                         current_module.is_ancestor_of(module) && !ptr::eq(current_module, *module)
                     })
-                    .map(|(_, module)| module.kind.name())
-                    .flatten(),
+                    .flat_map(|(_, module)| module.kind.name()),
             )
             .filter(|c| !c.to_string().is_empty())
             .collect::<Vec<_>>();
@@ -1859,7 +1858,7 @@ crate fn show_candidates(
         let instead = if instead { " instead" } else { "" };
         let mut msg = format!("consider importing {} {}{}", determiner, kind, instead);
 
-        for note in accessible_path_strings.iter().map(|cand| cand.3.as_ref()).flatten() {
+        for note in accessible_path_strings.iter().flat_map(|cand| cand.3.as_ref()) {
             err.note(note);
         }
 
@@ -1942,7 +1941,7 @@ crate fn show_candidates(
                 multi_span.push_span_label(span, format!("`{}`: not accessible", name));
             }
 
-            for note in inaccessible_path_strings.iter().map(|cand| cand.3.as_ref()).flatten() {
+            for note in inaccessible_path_strings.iter().flat_map(|cand| cand.3.as_ref()) {
                 err.note(note);
             }
 
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index f9926a71c30..129db038f4a 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -1163,7 +1163,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                         err.span_suggestion(
                             span,
                             &"use this syntax instead",
-                            format!("{path_str}"),
+                            path_str.to_string(),
                             Applicability::MaybeIncorrect,
                         );
                     }