fixes #3973

compiler/vm.nim

@@ -10,7 +10,9 @@
 ## This file implements the new evaluation engine for Nim code.
 ## An instruction is 1-3 int32s in memory, it is a register based VM.
 
-const debugEchoCode = false
+const
+  debugEchoCode = false
+  traceCode = debugEchoCode
 
 import ast except getstr
 
@@ -404,7 +406,8 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
     let instr = c.code[pc]
     let ra = instr.regA
     #if c.traceActive:
-    #echo "PC ", pc, " ", c.code[pc].opcode, " ra ", ra, " rb ", instr.regB, " rc ", instr.regC
+    when traceCode:
+      echo "PC ", pc, " ", c.code[pc].opcode, " ra ", ra, " rb ", instr.regB, " rc ", instr.regC
     #  message(c.debug[pc], warnUser, "Trace")
 
     case instr.opcode

compiler/vmgen.nim

@@ -1447,12 +1447,12 @@ proc getNullValue(typ: PType, info: TLineInfo): PNode =
   of tyObject:
     result = newNodeIT(nkObjConstr, info, t)
     result.add(newNodeIT(nkEmpty, info, t))
-    getNullValueAux(t.n, result)
     # initialize inherited fields:
     var base = t.sons[0]
     while base != nil:
       getNullValueAux(skipTypes(base, skipPtrs).n, result)
       base = base.sons[0]
+    getNullValueAux(t.n, result)
   of tyArray, tyArrayConstr:
     result = newNodeIT(nkBracket, info, t)
     for i in countup(0, int(lengthOrd(t)) - 1):

tests/vm/tinheritance.nim

@@ -0,0 +1,29 @@
+discard """
+  msg: '''Hello fred , managed by sally
+Hello sally , managed by bob'''
+"""
+# bug #3973
+
+type
+  EmployeeCode = enum
+    ecCode1,
+    ecCode2
+
+  Person* = object of RootObj
+    name* : string
+    last_name*: string
+
+  Employee* = object of Person
+    empl_code* : EmployeeCode
+    mgr_name* : string
+
+proc test() =
+  var
+    empl1 = Employee(name: "fred", last_name: "smith", mgr_name: "sally", empl_code: ecCode1)
+    empl2 = Employee(name: "sally", last_name: "jones", mgr_name: "bob", empl_code: ecCode2)
+
+  echo "Hello ", empl1.name, " , managed by ", empl1.mgr_name
+  echo "Hello ", empl2.name, " , managed by ", empl2.mgr_name
+
+static:
+  test()