Use `as_deref` in compiler (but only where it makes sense)

3 files changed, 4 insertions, 11 deletions

diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index 89aaa0b95e4..99c934862c4 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -304,7 +304,7 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
                 parse_sess_created(&mut sess.parse_sess);
             }
 
-            let temps_dir = sess.opts.unstable_opts.temps_dir.as_ref().map(|o| PathBuf::from(&o));
+            let temps_dir = sess.opts.unstable_opts.temps_dir.as_deref().map(PathBuf::from);
 
             let compiler = Compiler {
                 sess: Lrc::new(sess),
diff --git a/compiler/rustc_interface/src/queries.rs b/compiler/rustc_interface/src/queries.rs
index 91d180e1eb7..fc0b11183f7 100644
--- a/compiler/rustc_interface/src/queries.rs
+++ b/compiler/rustc_interface/src/queries.rs
@@ -33,11 +33,7 @@ pub struct Query<T> {
 
 impl<T> Query<T> {
     fn compute<F: FnOnce() -> Result<T>>(&self, f: F) -> Result<&Query<T>> {
-        let mut result = self.result.borrow_mut();
-        if result.is_none() {
-            *result = Some(f());
-        }
-        result.as_ref().unwrap().as_ref().map(|_| self).map_err(|err| *err)
+        self.result.borrow_mut().get_or_insert_with(f).as_ref().map(|_| self).map_err(|&err| err)
     }
 
     /// Takes ownership of the query result. Further attempts to take or peek the query
diff --git a/compiler/rustc_interface/src/util.rs b/compiler/rustc_interface/src/util.rs
index 2fe3fb2fa56..4142964a0da 100644
--- a/compiler/rustc_interface/src/util.rs
+++ b/compiler/rustc_interface/src/util.rs
@@ -68,10 +68,7 @@ pub fn create_session(
     let codegen_backend = if let Some(make_codegen_backend) = make_codegen_backend {
         make_codegen_backend(&sopts)
     } else {
-        get_codegen_backend(
-            &sopts.maybe_sysroot,
-            sopts.unstable_opts.codegen_backend.as_ref().map(|name| &name[..]),
-        )
+        get_codegen_backend(&sopts.maybe_sysroot, sopts.unstable_opts.codegen_backend.as_deref())
     };
 
     // target_override is documented to be called before init(), so this is okay
@@ -260,7 +257,7 @@ pub fn rustc_path<'a>() -> Option<&'a Path> {
 
     const BIN_PATH: &str = env!("RUSTC_INSTALL_BINDIR");
 
-    RUSTC_PATH.get_or_init(|| get_rustc_path_inner(BIN_PATH)).as_ref().map(|v| &**v)
+    RUSTC_PATH.get_or_init(|| get_rustc_path_inner(BIN_PATH)).as_deref()
 }
 
 fn get_rustc_path_inner(bin_path: &str) -> Option<PathBuf> {