LI77711: INCORRECT WARNING FOR UNREACHABLE STATEMENT with throw

XL C/C++ for Blue Gene/Q Fix Pack 12 (May 2015 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 14 (May 2016 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 15 (October 2017 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 6 (November 2013 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 7 (February 2014 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 8 (May 2014 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 9 (August 2014 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 10 (November 2014 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 11 (February 2015 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 13 (August 2015 Update) for 12.1

APAR status

• Closed as program error.

Error description

• When an exception is thrown, an undeserved message 1540-5340 is
  issued with the below test case.
  
  "xlc12_defect_infounreachable.cpp", line 14.4: 1540-5340 (I)
  The statement is unreachable.
  "xlc12_defect_infounreachable.cpp", line 16.8: 1540-5350 (I)
  The condition always evaluates to false.
  "xlc12_defect_infounreachable.cpp", line 16.15: 1540-5340 (I)
  The statement is unreachable.
  
  For the below example, only the first 1540-5340 is unexpected.
  The second is expected.
  
  ===== TESTCASE:
  $cat xlc12_defect_infounreachable.cpp
  #include <iostream>
  #include <stdexcept>
  #include <cstdlib>
  
  signed main(signed argc, char **) {
     signed result(EXIT_SUCCESS);
  
     if (1 == argc) {
        std::cout << "reachable" << std::endl;
     } else {
        std::string const msg("arg entered");
        std::runtime_error const e(msg);
        throw e;
     } // line 14
  
     if (false) {  //line 16
        std::cout << "unreachable" << std::endl;  //line 17
     }
  
     return result;
  }
  
  xlC -q'info=all' xlc12_defect_infounreachable.cpp
  

Local fix

• N/A, only warning.
  

Problem summary

• PROBLEM DESCRIPTION: Incorrect unreachable message was placed
  in compiler generated code, confusing the users.
  
  USERS AFFECTED: Users with -qinfo=rea option on
  

Problem conclusion

• The message is no longer being emitted incorrectly.
  

Temporary fix

Comments

APAR Information

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

  IV48141

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

Fix information

• Fixed component name

  XL C/C++ FOR BG

• Fixed component ID

  5799AG100

Applicable component levels