* src/misc/modgray.hh (loopless_modular_mixed_radix_gray_code::done,

loopless_modular_mixed_radix_gray_code::last): Declare as const.

src/misc/modgray.hh

@@ -110,14 +110,14 @@ namespace spot
     /// At this point it is still OK to call next(), and then done() will
     /// become true.
     bool
-    last()
+    last() const
     {
       return f_[0] == n_;
     }
 
     /// Whether all tuple have been explored.
     bool
-    done()
+    done() const
     {
       return done_;
     }