Auto merge of rust-lang#85538 - r00ster91:iterrepeat, r=Mark-Simulacrum

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

I noticed that there were some instances where `std::iter::repeat` would be used to repeat a string or a char to take a specific count of it and then collect it into a `String` when `str::repeat` is actually much faster and better for that.

See also: rust-lang/rust-clippy#7260.

compiler/rustc_typeck/src/check/mod.rs

@@ -849,7 +849,7 @@ 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);

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() {