Deprecate &bit-order on bit ranges.

This does not appear to have any effect and allowing it may be
confusing to users. Deprecate it with the idea of eventual
removal.

spicy/toolchain/src/compiler/visitors/validator.cc

@@ -752,6 +752,15 @@ struct VisitorPost : public hilti::visitor::PreOrder<void, VisitorPost>, public
                     error(fmt("'%s' can be used at most once", a), p);
             }
         }
+
+        if ( auto t = f.itemType().tryAs<type::Bitfield>() ) {
+            for ( const auto& b : t->bits() ) {
+                if ( AttributeSet::has(b.attributes(), "&bit-order") )
+                    hilti::logger().deprecated(fmt("&bit-order on bitfield item '%s' has no effect and is deprecated",
+                                                   b.id()),
+                                               b.meta().location());
+            }
+        }
     }
 
     void operator()(const spicy::type::unit::item::UnresolvedField& u, position_t p) {

tests/Baseline/spicy.types.bitfield.bit-bitorder/output

@@ -0,0 +1,3 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+[warning] <...>/bit-bitorder.spicy:14:5-14:56: &bit-order on bitfield item 'x1015_msb0' has no effect and is deprecated
+[warning] <...>/bit-bitorder.spicy:15:5-15:56: &bit-order on bitfield item 'x1015_lsb0' has no effect and is deprecated

tests/spicy/types/bitfield/bit-bitorder.spicy

@@ -0,0 +1,17 @@
+# @TEST-EXEC: spicyc -p -o /dev/null %INPUT 2>output
+# @TEST-EXEC: btest-diff output
+#
+# @TEST-DOC: Test deprecated "&bit-order" attribute on bits emits deprecation warning.
+
+module Mini;
+
+import spicy;
+
+public type X = unit {
+  be16_lsb0: bitfield(16) {
+    x0: 0;
+    x1015: 10..15;
+    x1015_msb0: 10..15 &bit-order=spicy::BitOrder::MSB0;
+    x1015_lsb0: 10..15 &bit-order=spicy::BitOrder::LSB0;
+  };
+};