IZ76950: INCORRECT MSG, WHEN RETURNING FUNCTION VALUE

October 2010 PTF for XL C/C++ for AIX, V10.1

APAR status

• Closed as program error.

Error description

• When compiling and running the provided testcase, the
  compiler produces a warning message indicating that you are
  trying to return the address of a local variable within the
  return expression.
  
  However, in the source code itself, the code is only trying to
  return the value returned by a function call.
  
  !* TEST CASE
  !* ---------
  !*
  !* testcase_xlC_10.cpp:
  !* #include "string.h"
  !*
  !* char *isUltimateAnswer(char *szAsciiz, int * piNum)
  !* {
  !*    if (*piNum == 42)
  !*       strcpy(szAsciiz, "Yes");
  !*    else
  !*       strcpy(szAsciiz, "No");
  !*    return szAsciiz;
  !* }
  !* char * AskDeepThought(char *szAsciiz)
  !* {
  !*    int iNum = 1;
  !*
  !*    return isUltimateAnswer(szAsciiz, &iNum);
  !* }
  !*
  !*
  !* ACTUAL OUTPUT
  !* -------------
  !*
  !*  "testcase_xlC_10.cpp", line 16.39: 1540-1103 (W) The address
  !*  of a local variable or temporary is used in a return
  !*  expression.
  !*
  !*
  

Local fix

• Create an intermediary object within the 'AskDeepThought'
  function
  
  char * AskDeepThought(char *szAsciiz)
  {
     int iNum = 1;
     char *szRet = isUltimateAnswer(szAsciiz, &iNum);
  
     return szRet;
  }
  

Problem summary

• PROBLEM DESCRIPTION:
  Incorrect compiler warning about returning the address of a
  local.
  
  USERS AFFECTED:
  Return statement passing the address of a local to a function
  that is used to return a pointer/reference.
  

Problem conclusion

• Backported fix from v11.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  LI75859 LI75888

Fix information

• Fixed component name

  XL C++ AIX

• Fixed component ID

  5724U8100

Applicable component levels