Adopt let else in more places

Author: est31

compiler/rustc_ast_lowering/src/asm.rs

@@ -338,9 +338,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
                                     let idx2 = *o.get();
                                     let &(ref op2, op_sp2) = &operands[idx2];
-                                    let reg2 = match op2.reg() {
-                                        Some(asm::InlineAsmRegOrRegClass::Reg(r)) => r,
-                                        _ => unreachable!(),
+                                    let Some(asm::InlineAsmRegOrRegClass::Reg(reg2)) = op2.reg() else {
+                                        unreachable!();
                                     };
 
                                     let msg = format!(

compiler/rustc_ast_lowering/src/expr.rs

@@ -326,9 +326,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
         args: Vec<AstP<Expr>>,
         legacy_args_idx: &[usize],
     ) -> hir::ExprKind<'hir> {
-        let path = match f.kind {
-            ExprKind::Path(None, ref mut path) => path,
-            _ => unreachable!(),
+        let ExprKind::Path(None, ref mut path) = f.kind else {
+            unreachable!();
         };
 
         // Split the arguments into const generics and normal arguments