Fix Issue 19008 - core.internal.convert.toUbyte doesn't work on enums

Author: n8sh

src/core/internal/convert.d

@@ -549,20 +549,28 @@ const(ubyte)[] toUbyte(T)(ref T val) if (is(Unqual!T == cfloat) || is(Unqual!T =
 }
 
 @trusted pure nothrow
-const(ubyte)[] toUbyte(T)(ref T val) if (is(T == enum) && is(typeof(toUbyte(cast(V)val)) == const(ubyte)[]))
+const(ubyte)[] toUbyte(T)(ref T val) if (is(T V == enum) && is(typeof(toUbyte(cast(V)val)) == const(ubyte)[]))
 {
     if (__ctfe)
     {
         static if (is(T V == enum)){}
-        V e_val = val;
-        return toUbyte(e_val);
+        return toUbyte(cast(V) val);
     }
     else
     {
         return (cast(const(ubyte)*)&val)[0 .. T.sizeof];
     }
 }
 
+nothrow pure @safe unittest
+{
+    // Issue 19008 - check toUbyte works on enums.
+    enum Month : uint { jan = 1}
+    Month m = Month.jan;
+    const bytes = toUbyte(m);
+    enum ctfe_works = (() => { Month x = Month.jan; return toUbyte(x).length > 0; })();
+}
+
 private bool isNonReference(T)()
 {
     static if (is(T == struct) || is(T == union))