[Bug c++/56190] New: GCC fails deducing a "void(*)(int, float, double)" to a "void(*)(T..., float, double)" with T={int}

[Bug c++/56190] New: GCC fails deducing a "void(*)(int, float, double)" to a "void(*)(T..., float, double)" with T={int}

[schaub.johannes at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56190

             Bug #: 56190
           Summary: GCC fails deducing a "void(*)(int, float, double)" to
                    a "void(*)(T..., float, double)" with T={int}
    Classification: Unclassified
           Product: gcc
           Version: 4.7.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: schaub.johannes@googlemail.com


From
http://stackoverflow.com/questions/14664589/variadic-template-code-compiles-on-gcc-4-6-but-not-on-clang-or-gcc-4-7
:

class Test {
    public:
    template <class... A2> void print (void(*function)(A2..., float, double)) {

    }
};

void test_print (int a, float b, double c) { }

int main () {
    Test test;
    test.print<int> (&test_print);
}

Fails with

source.cpp:14:33: note: candidate is:
source.cpp:3:33: note: template<class ... A2> void Test::print(void (*)(A2 ...,
float, double))
source.cpp:3:33: note:   template argument deduction/substitution failed:
source.cpp:14:33: note:   mismatched types 'float' and 'int'

GCC does apparently not substitute the explicitly specified arguments of "A2"
before attempting the argument deduction.

[Bug c++/56190] GCC fails deducing a "void(*)(int, float, double)" to a "void(*)(T..., float, double)" with T={int}

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56190

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-07-27
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug c++/56190] GCC fails deducing a "void(*)(int, float, double)" to a "void(*)(T..., float, double)" with T={int}

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56190

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |v.reshetnikov at gmail dot com

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 84893 has been marked as a duplicate of this bug. ***

[Bug c++/56190] GCC fails deducing a "void(*)(int, float, double)" to a "void(*)(T..., float, double)" with T={int}

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56190

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mohsen.tamiz at gmail dot com

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 69205 has been marked as a duplicate of this bug. ***

[Bug c++/56190] GCC fails deducing a "void(*)(int, float, double)" to a "void(*)(T..., float, double)" with T={int}

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56190

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |eliphat at sjtu dot edu.cn

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 104672 has been marked as a duplicate of this bug. ***

[Bug c++/56190] GCC fails deducing a "void(*)(int, float, double)" to a "void(*)(T..., float, double)" with T={int}

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56190

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hiraditya at msn dot com

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 105796 has been marked as a duplicate of this bug. ***

[Bug c++/56190] GCC fails deducing a "void(*)(int, float, double)" to a "void(*)(T..., float, double)" with T={int}

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56190

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Simplier example:
```
int func(int, char);

template<typename... TArgs>
int testFunc(int (*)(TArgs..., char));

int x = testFunc<int>(func);
```