match on chars instead of &strs for .split() or .strip_prefix()

compiler/rustc_hir_typeck/src/upvar.rs

@@ -932,7 +932,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         var_hir_id: hir::HirId,
         closure_clause: hir::CaptureBy,
     ) -> Option<FxIndexMap<UpvarMigrationInfo, UnordSet<&'static str>>> {
-        let auto_traits_def_id = vec![
+        let auto_traits_def_id = [
             self.tcx.lang_items().clone_trait(),
             self.tcx.lang_items().sync_trait(),
             self.tcx.get_diagnostic_item(sym::Send),

compiler/rustc_middle/src/traits/solve/inspect/format.rs

@@ -15,11 +15,11 @@ struct Indentor<'a, 'b> {
 
 impl Write for Indentor<'_, '_> {
     fn write_str(&mut self, s: &str) -> std::fmt::Result {
-        for line in s.split_inclusive("\n") {
+        for line in s.split_inclusive('\n') {
             if self.on_newline {
                 self.f.write_str("    ")?;
             }
-            self.on_newline = line.ends_with("\n");
+            self.on_newline = line.ends_with('\n');
             self.f.write_str(line)?;
         }
 

compiler/rustc_session/src/config.rs

@@ -279,11 +279,11 @@ impl LinkSelfContained {
         // set of all values like `y` or `n` used to be. Therefore, if this flag had previously been
         // set in bulk with its historical values, then manually setting a component clears that
         // `explicitly_set` state.
-        if let Some(component_to_enable) = component.strip_prefix("+") {
+        if let Some(component_to_enable) = component.strip_prefix('+') {
             self.explicitly_set = None;
             self.components.insert(component_to_enable.parse()?);
             Ok(())
-        } else if let Some(component_to_disable) = component.strip_prefix("-") {
+        } else if let Some(component_to_disable) = component.strip_prefix('-') {
             self.explicitly_set = None;
             self.components.remove(component_to_disable.parse()?);
             Ok(())

compiler/rustc_session/src/options.rs

@@ -1145,7 +1145,7 @@ mod parse {
         }
 
         // 2. Parse a list of enabled and disabled components.
-        for comp in s.split(",") {
+        for comp in s.split(',') {
             if slot.handle_cli_component(comp).is_err() {
                 return false;
             }

library/test/src/formatters/junit.rs

@@ -32,7 +32,7 @@ fn str_to_cdata(s: &str) -> String {
     let escaped_output = s.replace("]]>", "]]]]><![CDATA[>");
     let escaped_output = escaped_output.replace("<?", "<]]><![CDATA[?");
     // We also smuggle newlines as &#xa so as to keep all the output on one line
-    let escaped_output = escaped_output.replace("\n", "]]>&#xA;<![CDATA[");
+    let escaped_output = escaped_output.replace('\n', "]]>&#xA;<![CDATA[");
     // Prune empty CDATA blocks resulting from any escaping
     let escaped_output = escaped_output.replace("<![CDATA[]]>", "");
     format!("<![CDATA[{}]]>", escaped_output)