LI70536: WRONG WARNING MESSAGE "SUBSCRIPT IS LESS THAN 0"

Latest updates for XL C/C++ Advanced Edition V7 for Linux

APAR status

• Closed as program error.

Error description

• The C++ compiler generates a warning message:
  
  1540-2908 (W) The subscript -1 is less than zero.  The subscript
  of an array should be greater than or equal to zero.
  
  when compiling code that use the return value of a funtion that
  returns a pointer to char with the array subscript notation to
  do pointer arithmetic, when the value of the array subscript is
  less than zero.
  
  For example, compiling the following testcase:
  
  const char* ptr ();
  
  int foobar ()
  {
    return ptr ()[-1];
  }
  
  results in the warning message:
  
  "testcase.C", line 5.17: 1540-2908 (W) The subscript -1 is less
  than zero.  The subscript of an array should be greater than or
  equal to zero.
  

Local fix

• The warning message can be suppressed using the -qsuppress
  compiler option, specifically -qsuppress=1540-2908
  

Problem summary

• Same as submitter's text.
  

Problem conclusion

• The compiler looks for array indexing and checks for any
  obvious out of bounds indexing.  Part of the check is to
  find the name of the array being indexed.  In some cases
  like in this defect, the address of the memory being
  indexed is not derived from a variable name.  In these
  cases the compiler will think the array expression is
  derived off of an array and can continue the index check.
  

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:

  IY70440

Modules/Macros

• DEFSRXXX
  

Fix information

Applicable component levels

• R700 PSY

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