fixed a serious code generation bug leading to wrong RTTI

lib/system/excpt.nim

@@ -192,11 +192,7 @@ proc quitOrDebug() {.inline.} =
   else:
     endbStep() # call the debugger
 
-proc raiseException(e: ref E_Base, ename: CString) {.compilerRtl.} =
-  e.name = ename
-  when hasSomeStackTrace:
-    e.trace = ""
-    rawWriteStackTrace(e.trace)
+proc raiseExceptionAux(e: ref E_Base) =
   if localRaiseHook != nil:
     if not localRaiseHook(e): return
   if globalRaiseHook != nil:
@@ -205,7 +201,7 @@ proc raiseException(e: ref E_Base, ename: CString) {.compilerRtl.} =
     pushCurrentException(e)
     c_longjmp(excHandler.context, 1)
   elif e[] of EOutOfMemory:
-    writeToStdErr(ename)
+    writeToStdErr(e.name)
     quitOrDebug()
   else:
     when hasSomeStackTrace:
@@ -214,7 +210,7 @@ proc raiseException(e: ref E_Base, ename: CString) {.compilerRtl.} =
       add(buf, "Error: unhandled exception: ")
       if not isNil(e.msg): add(buf, e.msg)
       add(buf, " [")
-      add(buf, $ename)
+      add(buf, $e.name)
       add(buf, "]\n")
       writeToStdErr(buf)
     else:
@@ -230,16 +226,23 @@ proc raiseException(e: ref E_Base, ename: CString) {.compilerRtl.} =
       add(buf, "Error: unhandled exception: ")
       if not isNil(e.msg): add(buf, e.msg)
       add(buf, " [")
-      xadd(buf, ename, c_strlen(ename))
+      xadd(buf, e.name, c_strlen(e.name))
       add(buf, "]\n")
       writeToStdErr(buf)
     quitOrDebug()
 
+proc raiseException(e: ref E_Base, ename: CString) {.compilerRtl.} =
+  e.name = ename
+  when hasSomeStackTrace:
+    e.trace = ""
+    rawWriteStackTrace(e.trace)
+  raiseExceptionAux(e)
+
 proc reraiseException() {.compilerRtl.} =
   if currException == nil:
     raise newException(ENoExceptionToReraise, "no exception to reraise")
   else:
-    raiseException(currException, currException.name)
+    raiseExceptionAux(currException)
 
 proc WriteStackTrace() =
   when hasSomeStackTrace: