fixes symbolName for range enums (#24052)

lib/std/enumutils.nim

@@ -174,6 +174,9 @@ template symbolRank*[T: enum](a: T): int =
   when T is Ordinal: ord(a) - T.low.ord.static
   else: symbolRankImpl(a)
 
+proc rangeBase(T: typedesc): typedesc {.magic: "TypeTrait".}
+  # skip one level of range; return the base type of a range type
+
 func symbolName*[T: enum](a: T): string =
   ## Returns the symbol name of an enum.
   ##
@@ -192,5 +195,8 @@ func symbolName*[T: enum](a: T): string =
       c1 = 4
       c2 = 20
     assert c1.symbolName == "c1"
-  const names = enumNames(T)
+  when T is range:
+    const names = enumNames(rangeBase T)
+  else:
+    const names = enumNames(T)
   names[a.symbolRank]

tests/stdlib/tenumutils.nim

@@ -35,5 +35,15 @@ template main =
     doAssert $b == "kb0"
     static: doAssert B.high.symbolName == "b2"
 
+  block:
+    type
+      Color = enum
+        Red = "red", Yellow = "yellow", Blue = "blue"
+
+    var s = Red
+    doAssert symbolName(s) == "Red"
+    var x: range[Red..Blue] = Yellow
+    doAssert symbolName(x) == "Yellow"
+
 static: main()
 main()