fixes #11205

compiler/enumtostr.nim

@@ -40,3 +40,59 @@ proc genEnumToStrProc*(t: PType; info: TLineInfo; g: ModuleGraph): PSym =
   n.sons[resultPos] = newSymNode(res)
   result.ast = n
   incl result.flags, sfFromGeneric
+
+proc searchObjCase(obj: PNode; field: PSym): PNode =
+  case obj.kind
+  of nkSym:
+    result = nil
+  of nkElse, nkOfBranch:
+    result = searchObjCase(obj.lastSon, field)
+  else:
+    if obj.kind == nkRecCase and obj[0].kind == nkSym and obj[0].sym == field:
+      result = obj
+    else:
+      for x in obj:
+        result = searchObjCase(x, field)
+        if result != nil: break
+
+proc genCaseObjDiscMapping*(t: PType; field: PSym; info: TLineInfo; g: ModuleGraph): PSym =
+  result = newSym(skProc, getIdent(g.cache, "objDiscMapping"), t.owner, info)
+
+  let dest = newSym(skParam, getIdent(g.cache, "e"), result, info)
+  dest.typ = field.typ
+
+  let res = newSym(skResult, getIdent(g.cache, "result"), result, info)
+  res.typ = getSysType(g, info, tyUInt8)
+
+  result.typ = newType(tyProc, t.owner)
+  result.typ.n = newNodeI(nkFormalParams, info)
+  rawAddSon(result.typ, res.typ)
+  addSon(result.typ.n, newNodeI(nkEffectList, info))
+
+  result.typ.addParam dest
+
+  var body = newNodeI(nkStmtList, info)
+  var caseStmt = newNodeI(nkCaseStmt, info)
+  caseStmt.add(newSymNode dest)
+
+  let subObj = searchObjCase(t.n, field)
+  doAssert subObj != nil
+  for i in 1 ..< subObj.len:
+    let ofBranch = subObj[i]
+    var newBranch = newNodeI(ofBranch.kind, ofBranch.info)
+    for j in 0..ofBranch.len-2:
+      newBranch.add ofBranch[j]
+
+    newBranch.add newTree(nkStmtList, newTree(nkFastAsgn, newSymNode(res), newIntNode(nkInt8Lit, i)))
+    caseStmt.add newBranch
+
+  body.add(caseStmt)
+
+  var n = newNodeI(nkProcDef, info, bodyPos+2)
+  for i in 0 ..< n.len: n.sons[i] = newNodeI(nkEmpty, info)
+  n.sons[namePos] = newSymNode(result)
+  n.sons[paramsPos] = result.typ.n
+  n.sons[bodyPos] = body
+  n.sons[resultPos] = newSymNode(res)
+  result.ast = n
+  incl result.flags, sfFromGeneric