fixes #21280; Enum with int64.high() value crashes compiler (#21285)

* fixes #21280; Enum with int64.high() value crashes compiler

* Update tests/enum/tenum.nim

* Update tests/enum/tenum.nim

* fixes tests

* Update tests/enum/tenum.nim

---------

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

compiler/semtypes.nim

@@ -16,6 +16,7 @@ const
   errIntLiteralExpected = "integer literal expected"
   errWrongNumberOfVariables = "wrong number of variables"
   errInvalidOrderInEnumX = "invalid order in enum '$1'"
+  errOverflowInEnumX = "The enum '$1' exceeds its maximum value ($2)"
   errOrdinalTypeExpected = "ordinal type expected; given: $1"
   errSetTooBig = "set is too large; use `std/sets` for ordinal types with more than 2^16 elements"
   errBaseTypeMustBeOrdinal = "base type of a set must be an ordinal"
@@ -147,7 +148,11 @@ proc semEnum(c: PContext, n: PNode, prev: PType): PType =
         declarePureEnumField(c, e)
     if (let conflict = strTableInclReportConflict(symbols, e); conflict != nil):
       wrongRedefinition(c, e.info, e.name.s, conflict.info)
-    inc(counter)
+    if counter == high(typeof(counter)):
+      if i > 1 and result.n[i-2].sym.position == high(int):
+        localError(c.config, n[i].info, errOverflowInEnumX % [e.name.s, $high(typeof(counter))])
+    else:
+      inc(counter)
   if isPure and sfExported in result.sym.flags:
     addPureEnum(c, LazySym(sym: result.sym))
   if tfNotNil in e.typ.flags and not hasNull:

tests/enum/tenum.nim

@@ -176,3 +176,11 @@ block: # bug #12589
 
     when not defined(gcRefc):
       doAssert $typ() == "wkbPoint25D"
+
+    block: # bug #21280
+      type
+        Test = enum
+          B = 19
+          A = int64.high()
+
+      doAssert ord(A) == int64.high()