Avoid using time API when we don't need it

This avoids a syscall to the time API when the result is ignored later anyway.

This allows to use the library with default options on wasm32-unknown-unknown, where the unimplemented syscall would panic otherwise.

src/lib.rs

@@ -784,19 +784,25 @@ fn perform_reductions(
     try_alpha_reductions(png, &opts.alphas, eval);
 }
 
+struct DeadlineImp {
+    start: Instant,
+    timeout: Duration,
+    print_message: AtomicBool,
+}
+
 /// Keep track of processing timeout
 pub(crate) struct Deadline {
-    start: Instant,
+    imp: Option<DeadlineImp>,
-    timeout: Option<Duration>,
-    print_message: AtomicBool,
 }
 
 impl Deadline {
     pub fn new(timeout: Option<Duration>, verbose: bool) -> Self {
         Self {
+            imp: timeout.map(|timeout| DeadlineImp {
                 start: Instant::now(),
                 timeout,
                 print_message: AtomicBool::new(verbose),
+            })
         }
     }
 
@@ -804,11 +810,11 @@ impl Deadline {
     ///
     /// If the verbose option is on, it also prints a timeout message once.
     pub fn passed(&self) -> bool {
-        if let Some(timeout) = self.timeout {
+        if let Some(imp) = &self.imp {
-            let elapsed = self.start.elapsed();
+            let elapsed = imp.start.elapsed();
-            if elapsed > timeout {
+            if elapsed > imp.timeout {
-                if self.print_message.load(Ordering::Relaxed) {
+                if imp.print_message.load(Ordering::Relaxed) {
-                    self.print_message.store(false, Ordering::Relaxed);
+                    imp.print_message.store(false, Ordering::Relaxed);
                     eprintln!("Timed out after {} second(s)", elapsed.as_secs());
                 }
                 return true;