PH40309: INCORRECT LOOP EXECUTION WHEN COMPILING WITH Z/OS COMPILER

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When going through the assembler code of the while loop
  condition, the problem is that the assignment is performed
  twice, so the first element of t is skipped. If t has more
  elements, the 1st, 3rd, etc. elements are skipped.
  
  The following test case demonstrates this issue:
  
  ===== COMPILE COMMAND:
  c++ test.cpp
  
  
  ===== TESTCASE:
  $cat test.cpp
  #include <stdio.h>
  int main()
  {
      int i = 0;
      const int t[2] = { 1 };
      while (const int x = t[i++])
     {
          printf("In loop: i=%d\n", i);
     }
     printf("After loop: i=%d\n", i);
  
    return 0;
  }
  $
  
  
  ===== ACTUAL OUTPUT:
  $./a.out
  After loop: i=2
  $
  
  
  
  ===== EXPECTED OUTPUT:
  $ ./a.out
  In loop: i=1
  After loop: i=2
  $
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of the zosv2r4 C/C++ compiler          *
  ****************************************************************
  When going through the assembler code of the while loop
  condition, the problem is that the assignment is performed
  twice, so the first element of t is skipped. If it has more
  elements, the 1st, 3rd, etc. elements are skipped.
  

Problem conclusion

• Apply service provided.
  

Temporary fix

Comments

APAR Information

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

  PH18274

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

  UI77052

Modules/Macros

• CCNECICS CCNECWI  CCNED230 CCNEDSCT CCNEDWRT CCNEFILT CCNEHIFC
  CCNEIPA3 CCNEIPAO CCNEMDEP CCNEOPTP CCNEP    CCNEPP   CCNETBY
  CCNMSGE  CCNMSGT  CCNQIPA
  

Fix information

• Fixed component name

  C/C++ FOR MVS

• Fixed component ID

  56551210A

Applicable component levels

• R7B0 PSY UI77052

     UP21/09/29 P F109

Fix is available

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