Convert consecutive String::push_str to String::extend

Author: paolobarbolini

compiler/rustc_ast/src/ast.rs

@@ -181,8 +181,7 @@ pub fn join_path_syms(path: impl IntoIterator<Item = impl Borrow<Symbol>>) -> St
     for sym in iter {
         let sym = *sym.borrow();
         debug_assert_ne!(sym, kw::PathRoot);
-        s.push_str("::");
-        s.push_str(sym.as_str());
+        s.extend(["::", sym.as_str()]);
     }
     s
 }
@@ -201,8 +200,7 @@ pub fn join_path_idents(path: impl IntoIterator<Item = impl Borrow<Ident>>) -> S
     for ident in iter {
         let ident = *ident.borrow();
         debug_assert_ne!(ident.name, kw::PathRoot);
-        s.push_str("::");
-        s.push_str(&ident.to_string());
+        s.extend(["::", &ident.to_string()]);
     }
     s
 }

compiler/rustc_builtin_macros/src/assert/context.rs

@@ -334,9 +334,7 @@ impl<'cx, 'a> Context<'cx, 'a> {
         if self.paths.contains(&path_ident) {
             return;
         } else {
-            self.fmt_string.push_str("  ");
-            self.fmt_string.push_str(path_ident.as_str());
-            self.fmt_string.push_str(" = {:?}\n");
+            self.fmt_string.extend(["  ", path_ident.as_str(), " = {:?}\n"]);
             let _ = self.paths.insert(path_ident);
         }
         let curr_capture_idx = self.capture_decls.len();

library/alloc/src/borrow.rs

@@ -13,8 +13,6 @@ use core::ops::{Deref, DerefPure};
 use Cow::*;
 
 use crate::fmt;
-#[cfg(not(no_global_oom_handling))]
-use crate::string::String;
 
 // FIXME(inference): const bounds removed due to inference regressions found by crater;
 //   see https://github.com/rust-lang/rust/issues/147964
@@ -496,12 +494,14 @@ impl<'a> AddAssign<&'a str> for Cow<'a, str> {
         if self.is_empty() {
             *self = Cow::Borrowed(rhs)
         } else if !rhs.is_empty() {
-            if let Cow::Borrowed(lhs) = *self {
-                let mut s = String::with_capacity(lhs.len() + rhs.len());
-                s.push_str(lhs);
-                *self = Cow::Owned(s);
+            match self {
+                Self::Borrowed(lhs) => {
+                    *self = Cow::Owned([lhs, rhs].into_iter().collect());
+                }
+                Self::Owned(lhs) => {
+                    lhs.push_str(&rhs);
+                }
             }
-            self.to_mut().push_str(rhs);
         }
     }
 }
@@ -513,12 +513,14 @@ impl<'a> AddAssign<Cow<'a, str>> for Cow<'a, str> {
         if self.is_empty() {
             *self = rhs
         } else if !rhs.is_empty() {
-            if let Cow::Borrowed(lhs) = *self {
-                let mut s = String::with_capacity(lhs.len() + rhs.len());
-                s.push_str(lhs);
-                *self = Cow::Owned(s);
+            match self {
+                Self::Borrowed(lhs) => {
+                    *self = Cow::Owned([&*lhs, &*rhs].into_iter().collect());
+                }
+                Self::Owned(lhs) => {
+                    lhs.push_str(&rhs);
+                }
             }
-            self.to_mut().push_str(&rhs);
         }
     }
 }

src/librustdoc/html/markdown.rs

@@ -1645,9 +1645,7 @@ pub(crate) fn plain_text_from_events<'a>(
         match &event {
             Event::Text(text) => s.push_str(text),
             Event::Code(code) => {
-                s.push('`');
-                s.push_str(code);
-                s.push('`');
+                s.extend(["`", code, "`"]);
             }
             Event::HardBreak | Event::SoftBreak => s.push(' '),
             Event::Start(Tag::CodeBlock(..)) => break,

src/librustdoc/html/render/print_item.rs

@@ -2257,8 +2257,7 @@ pub(crate) fn compare_names(left: &str, right: &str) -> Ordering {
 
 pub(super) fn full_path(cx: &Context<'_>, item: &clean::Item) -> String {
     let mut s = join_path_syms(&cx.current);
-    s.push_str("::");
-    s.push_str(item.name.unwrap().as_str());
+    s.extend(["::", item.name.unwrap().as_str()]);
     s
 }