[Bug c++/17132] New: GCC fails to eliminate function template specialization when argument deduction fails

["achovane at engin dot umich dot edu" <gcc-bugzilla at gcc dot gnu dot org>]

When compiling test_no_amperspand.cpp, GCC generates the following error:

"error: `operator*' is not a member of type `empty'"

GCC attempts to instantiate a specialization of the function template 'test' 
which accepts a parameter of type `func_tag<Type, Type::operator*> *' with a 
default value of 0.

Since type 'empty' is a struct which does not overload `operator*', this 
specialization should not be included in the set of candidate functions for the 
call to `test' on line 19, according to the SFINAE (substitution-failure-is-not 
an-error) principle.

The C++ Standard states:

"... For each function template, if the argument deduction and checking 
succeeds, the template-arguments (deduced and/or explicit) are used to 
instantiate a single function template specialization which is added to the 
candidate functions set to be used in overload resolution. If, for a given 
function template, argument deduction fails, no such function is added to the 
set of candidate functions for that template."

Since a non-template function `test' is defined which accepts a parameter of 
type `void *', the call on 19 is satisfied. Thus, this program is correct and 
should compile.


The second file, test_amperspand.cpp, is identical to the first, except that on 
line 14, `Type::operator*' is replaced with `&Type::operator*'. (Both forms are 
correct.)

In the latter case (test_amperspand.cpp), GCC generates the following error:

"internal compiler error: Segmentation fault"


Both of these programs compile without error under Intel C++ 8.0 and Comeau 
C/C++ 4.3.0.

-- 
           Summary: GCC fails to eliminate function template specialization
                    when argument deduction fails
           Product: gcc
           Version: 3.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: achovane at engin dot umich dot edu
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17132