Resolve manual_let_else pedantic clippy lint

    warning: this could be rewritten as `let...else`
      --> build.rs:8:5
       |
     8 | /     let minor = match rustc_minor_version() {
     9 | |         Some(minor) => minor,
    10 | |         None => return,
    11 | |     };
       | |______^ help: consider writing: `let Some(minor) = rustc_minor_version() else { return };`
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_let_else
       = note: `-W clippy::manual-let-else` implied by `-W clippy::pedantic`
       = help: to override `-W clippy::pedantic` add `#[allow(clippy::manual_let_else)]`

    warning: this could be rewritten as `let...else`
      --> src/spanned.rs:31:5
       |
    31 | /     let first = match iter.next() {
    32 | |         Some(span) => span,
    33 | |         None => return Span::call_site(),
    34 | |     };
       | |______^ help: consider writing: `let Some(first) = iter.next() else { return Span::call_site() };`
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_let_else
       = note: `-W clippy::manual-let-else` implied by `-W clippy::pedantic`
       = help: to override `-W clippy::pedantic` add `#[allow(clippy::manual_let_else)]`

Author: dtolnay

build.rs

@@ -5,9 +5,8 @@ use std::str;
 fn main() {
     println!("cargo:rerun-if-changed=build.rs");
 
-    let minor = match rustc_minor_version() {
-        Some(minor) => minor,
-        None => return,
+    let Some(minor) = rustc_minor_version() else {
+        return;
     };
 
     if minor >= 77 {

src/spanned.rs

@@ -28,9 +28,8 @@ impl<T: ?Sized + ToTokens> Spanned for T {
 fn join_spans(tokens: TokenStream) -> Span {
     let mut iter = tokens.into_iter().map(|tt| tt.span());
 
-    let first = match iter.next() {
-        Some(span) => span,
-        None => return Span::call_site(),
+    let Some(first) = iter.next() else {
+        return Span::call_site();
     };
 
     iter.fold(None, |_prev, next| Some(next))