Replace some std::iter::repeat with str::repeat

Author: wooster0

Diff for: compiler/rustc_typeck/src/check/mod.rs

@@ -858,7 +858,7 @@ fn missing_items_err(
     // Obtain the level of indentation ending in `sugg_sp`.
     let indentation = tcx.sess.source_map().span_to_margin(sugg_sp).unwrap_or(0);
     // Make the whitespace that will make the suggestion have the right indentation.
-    let padding: String = std::iter::repeat(" ").take(indentation).collect();
+    let padding: String = " ".repeat(indentation);
 
     for trait_item in missing_items {
         let snippet = suggestion_signature(&trait_item, tcx);

Diff for: src/test/ui/issues/issue-20644.rs

@@ -19,9 +19,7 @@ use std::path::Path;
 
 pub fn parse_summary<R: Read>(_: R, _: &Path) {
      let path_from_root = Path::new("");
-     Path::new(&iter::repeat("../")
-               .take(path_from_root.components().count() - 1)
-               .collect::<String>());
+     Path::new(&"../".repeat(path_from_root.components().count() - 1));
  }
 
 fn foo() {

Diff for: src/tools/clippy/clippy_lints/src/mem_discriminant.rs

@@ -7,7 +7,6 @@ use rustc_errors::Applicability;
 use rustc_hir::{BorrowKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use std::iter;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for calls of `mem::discriminant()` on a non-enum type.
@@ -67,7 +66,7 @@ impl<'tcx> LateLintPass<'tcx> for MemDiscriminant {
                                 }
                             }
 
-                            let derefs: String = iter::repeat('*').take(derefs_needed).collect();
+                            let derefs = "*".repeat(derefs_needed);
                             diag.span_suggestion(
                                 param.span,
                                 "try dereferencing",

Diff for: src/tools/clippy/clippy_lints/src/methods/clone_on_copy.rs

@@ -8,7 +8,6 @@ use rustc_hir::{BindingAnnotation, Expr, ExprKind, MatchSource, Node, PatKind};
 use rustc_lint::LateContext;
 use rustc_middle::ty::{self, adjustment::Adjust};
 use rustc_span::symbol::{sym, Symbol};
-use std::iter;
 
 use super::CLONE_DOUBLE_REF;
 use super::CLONE_ON_COPY;
@@ -54,8 +53,8 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, method_name: Symbol,
                             ty = inner;
                             n += 1;
                         }
-                        let refs: String = iter::repeat('&').take(n + 1).collect();
-                        let derefs: String = iter::repeat('*').take(n).collect();
+                        let refs = "&".repeat(n + 1);
+                        let derefs = "*".repeat(n);
                         let explicit = format!("<{}{}>::clone({})", refs, ty, snip);
                         diag.span_suggestion(
                             expr.span,