Rollup merge of #124287 - 41Leahcim:master, r=fmease

Improved code with clippy

I haven't used the bootstrapped compiler, but I think I have made some improvements using clippy. I have already made the following changes to the compiler:
Replaced `self.first().is_digit(10)` with `self.first().is_ascii_digit()` on lines 633, 664, and 680 of compiler/rust_lexer/src/lib.rs.

Removed unnecessary cast on line 262 of compiler/rustc_lexer/src/unescape.rs

Replaced ok_or_else with ok_or on line 303 of compiler/rustc_lexer/src/unescape.rs

Replaced `!std::env::var("RUSTC_BOOTSTRAP").is_ok()` with `std::env::var("RUSTC_BOOTSTRAP").is_err()` on line 4 of compiler/rustc_macros/build.rs

Removed needless borrow for generic argument `env`on line 53 of compiler/rust_llvm/build.rs

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler/rustc_llvm/build.rs b/compiler/rustc_llvm/build.rs
index 66ca94d1d9c..024f6f89a4b 100644
--- a/compiler/rustc_llvm/build.rs
+++ b/compiler/rustc_llvm/build.rs
@@ -50,7 +50,7 @@ fn detect_llvm_link() -> (&'static str, &'static str) {
 fn restore_library_path() {
     let key = tracked_env_var_os("REAL_LIBRARY_PATH_VAR").expect("REAL_LIBRARY_PATH_VAR");
     if let Some(env) = tracked_env_var_os("REAL_LIBRARY_PATH") {
-        env::set_var(&key, &env);
+        env::set_var(&key, env);
     } else {
         env::remove_var(&key);
     }