LI76650: TEMPLATE INSTANTIATION PROBLEM

XL C/C++ for Linux Fix Pack 9 (August 2013 Update) for 11.1
June 2012 Update for XL C/C++ for Linux, V11.1
October 2012 Update for XL C/C++ for Linux, V11.1
XL C/C++ for Linux Fix Pack 8 (June 2013 Update) for 11.1

APAR status

• Closed as program error.

Error description

• Consider the following test.cpp:
  
  ///////////// test.cpp //////////////////////
  struct A {
    int bar() { return 0; }
    int bar() const { return 1; }
  };
  template<typename T> void foo(T A::*) { }            // (1)
  template<typename T> void foo(T (A::*)() const) { }  // (2)
  int main() { foo(&A::bar); }                         // should
  expand via (2) above
  // XL C/C++ compiler cannot decide between (1) & (2)
  //////////////end of test.cpp ///////////////
  
  $xlC test.cpp
  "test.cpp", line 7.14: 1540-0219 (S) The call to "foo" has no
  best match.
  "test.cpp", line 7.18: 1540-1229 (I) Argument number 1 is an
  rvalue of type "overloaded function: A::bar".
  "test.cpp", line 6.27: 1540-1202 (I) No candidate is better
  than "foo<int>(int (A::*)() const)".
  "test.cpp", line 7.18: 1540-1231 (I) The conversion from
  argument number 1 to "int (A::*)() const" uses the resolved
  overloaded function "int A::bar() const".
  "test.cpp", line 5.27: 1540-1202 (I) No candidate is better
  than "foo<int ()>(int (A::*)())".
  "test.cpp", line 7.18: 1540-1231 (I) The conversion from
  argument number 1 to "int (A::*)()" uses the resolved overloaded
  function "int A::bar()".
  

Local fix

• N/A
  

Problem summary

• When applying template argument deduction with a type A that is
  a pointer to non-static member function type, the corresponding
  type P must match the cv-qualifier-seq of the type A exactly
  when using XL C/C++ for deduction to succeed. This may cause
  deduction to succeed where it would otherwise fail when the
  type of A is the address of a member function overloaded on the
  cv-qualifier-seq.
  

Problem conclusion

• Fix is enabled with -qxflag=FunctionCVTmplArgDeduction2011
  which also sets macro __IBMCPP_FUNC_CV_TMPL_ARG_DEDUCTION to 1.
  The new behaviour may become the default in a future release.
  Handling of cv-qualifier-seq in function types and
  cv-qualification is modified in template argument deduction.
  

Temporary fix

Comments

APAR Information

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

  IV11365

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

Fix information

• Fixed component name

  XL C/C++ FOR LI

• Fixed component ID

  5724X1400

Applicable component levels

• RB10 PSN IV11365

     UP06/09/13