PH70869: C++ EXTERN STORAGE CLASS SPECIFIER NOT AFFECTING FUNCTION TYPEDEF

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The extern "linkage_specification" syntax for defining external
  linkage types is not affecting the linkage mode the C++ compiler
  is using when generating calls to typedef'ed function types.
  Depending on the required linkage type, this may cause undefined
  behaviour or application crashes, particularly when managing
  parameter lists for function calls between Standard OS-style
  linkage and XPLINK.
    ===  TEST CASE  ===
  
  #include <stdlib.h>
  
  extern "OS_UPSTACK"
  
  {
  
     typedef int func_type_with_linkage(const char *);
  }
  
  int main() {
     static func_type_with_linkage *my_function = nullptr;
     my_function = (func_type_with_linkage *)(fetch("BPXWDY2"));
  
     my_function("ALLOC FI(SYSOUT) SYSOUT(X) MSG(2)");
  }
  
  $ ibm-clang++ -m32 -D_EXT apar.cpp -o apar
  

Local fix

• Refactor the C++ extern declaration into a C-style #pragma
  linkage statement (https://www.ibm.com/docs/en/open-xl-c-cpp-zo
  s/2.2.0?topic=sp-pragma-linkage)
  
  typedef int func_type_with_linkage(const char *);
  
  #pragma linkage (func_type_with_linkage,OS_UPSTACK)
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users with extern"OS" or "OS_UPSTACK"        *
  *                 specified on a typedef for a function type   *
  ****************************************************************
  * PROBLEM DESCRIPTION: Compiler ignores calling convention     *
  *                      specified by 'extern' keyword if it is  *
  *                      specified on a typedef.                 *
  ****************************************************************
  * RECOMMENDATION: Install PTF                                  *
  ****************************************************************
  When constructing the typedef's type, the compiler did not
  consult the pragma linkage specification. Consequently, any
  function later declared with this typedef defaulted
  /to the standard calling convention rather than the linkage
  mandated by the pragma.
  

Problem conclusion

• The compiler was corrected to register the pragma-specified
  calling convention during creation of the typedef's type.
  Consequently, functions declared using this typedef
  now receive the correct calling convention.
  

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:

Modules/Macros

• CNWC001  CNWC002  CNWC003  CNWC004  CNWC005  CNWC006  CNWC007
  CNWC008  CNWC009  CNWC00A  CNWC00B  CNWC00C  CNWC00D  CNWC00E
  CNWC00F  CNWC010  CNWC011  CNWC012  CNWC013  CNWC014  CNWC015
  CNWC016  CNWC017  CNWC018  CNWC019  CNWC01A  CNWC01B  CNWC01C
  CNWC01D  CNWC01E  CNWC01F  CNWC020  CNWC021  CNWC022  CNWC023
  CNWC024  CNWC025  CNWC026  CNWCH006 CNWCH00A CNWCH00B CNWLDMD
  CNWOX220 CNWPH0B3 CNWPH107 CNWPH146 CNWPH20D CNWPH2E3 CNWPH31E
  CNWPH334 CNWPH446 CNWPH55F CNWPH673 CNWPHPAX CNWRN$P0 CNWRN$PX
  CNWRNH00 CNWRNH01 CNWRNH02 CNWRNH03 CNWRNH04 CNWRNH05 CNWRNH06
  CNWRNH07 CNWRNH08 CNWRNH09 CNWRNH0A CNWRNH0B CNWRNH0C CNWRNH0D
  CNWRNH0E CNWRNH0F CNWRNH10 CNWRNH11 CNWRNH12 CNWRNH13 CNWRNH14
  CNWRNH15 CNWRNH16 CNWRNH17 CNWRNH18 CNWRNH19 CNWRNH1A CNWRNH1B
  CNWRNH1C CNWRNH1D CNWRNH1E CNWRNH1F CNWRNH20 CNWRNH21 CNWRNH22
  CNWRNH23 CNWRNH24 CNWRNH25 CNWRNH26 CNWRNH27 CNWRNH28 CNWRNH29
  CNWRNH2A CNWRNH2B CNWRNH2C CNWRNH2D CNWRNH2E CNWRNH2F CNWRNH30
  CNWRNH31 CNWRNH32 CNWRNH33 CNWRNH34 CNWRNH35 CNWRNH36 CNWRNH37
  CNWRNH38 CNWRNH39 CNWRNH3A CNWRNH3B CNWRNH3C CNWRNH3D CNWRNH3E
  CNWRNH3F CNWRNH40 CNWRNH41 CNWRNH42 CNWRNH43 CNWRNH44 CNWRNH45
  CNWRNH46 CNWRNH47 CNWRNH48 CNWRNH49 CNWRNH4A CNWRNH4B CNWRNH4C
  CNWRNH4D CNWRNH4E CNWRNH4F CNWRNH50 CNWRNH51 CNWRNH52 CNWRNH53
  CNWRNH54 CNWRNH55 CNWRNH56 CNWRNH57 CNWRNH58 CNWRNH59 CNWRNH5A
  CNWRNH5B CNWRNH5C CNWRNH5D CNWRNH5E CNWRNH5F CNWRNH60 CNWRNH61
  CNWRNH62 CNWRNH63 CNWRNH64 CNWRNH65 CNWRNH66 CNWRNH67 CNWRNH68
  CNWRNH69 CNWRNH6A CNWRNH6B CNWRNH6C CNWRNH6D CNWRNH6E CNWRNH6F
  CNWRNH70 CNWRNH71 CNWRNH72 CNWRNH73 CNWRNH74 CNWRNH75 CNWRNH76
  CNWRNH77 CNWRNH78 CNWRNH79 CNWRNH7A CNWRNH7B CNWRNH7C CNWRNH7D
  CNWRNH7E CNWRNH7F CNWRNH80 CNWRNH81 CNWRNH82 CNWRNH83 CNWRNH84
  CNWRNH85 CNWRNH86 CNWRNH87 CNWRNH88 CNWRNH89 CNWRNH8A CNWRNH8B
  CNWRNH8C CNWRNH8D CNWRNH8E CNWRNH8F CNWRNH90 CNWRNH91 CNWRNH92
  CNWRNH93 CNWRNH94 CNWRNH95 CNWRNH96 CNWRNH99 CNWRNH9A CNWRNH9B
  CNWRNH9C CNWRNH9D CNWRNH9E CNWRNH9F CNWRNHA0 CNWRNHA1 CNWRNHA2
  CNWRNHA3 CNWRNHA4 CNWRNHA5 CNWRNHA6 CNWRNHA7 CNWRNHA8 CNWRNHA9
  CNWRNHAB CNWRNHAC CNWRNHAD CNWRNHAE CNWRNHAF CNWRNHB0 CNWRNHB1
  CNWRNHB2 CNWRNHB3 CNWRNHB4 CNWRNHB5 CNWRNHB6 CNWRNHB7 CNWRNN00
  CNWRNN01 CNWRNN02 CNWRNN03 CNWRNN04 CNWRNN05 CNWRNN06 CNWRNN07
  

Fix information

• Fixed component name

  C/C++ FOR MVS

• Fixed component ID

  56551210A

Applicable component levels

• R7C4 PSY UO07991

     UP26/07/02 P F606

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.