[Bug c++/80026] New: Regression: passing unresolved function pointer to variadic function template yields "too many arguments" error

["gcc at arne-mertz dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80026

            Bug ID: 80026
           Summary: Regression: passing unresolved function pointer to
                    variadic function template yields "too many arguments"
                    error
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc@arne-mertz.de
  Target Milestone: ---

Consider the following code:

    void g(int) {}
    void g(bool){}

    template <class...S>
    void f(S...){}

    int main(){
      f(&g);
    }


As of 4.4.7 this gives "error: no matching function for call to 'f(<unresolved
overloaded function type>)'" which does not directly state the error but is
somewhat informative.
Since at least 4.6.4 until 7.0.1 I get "error: too many arguments to function
'void f(S ...) [with S = {}]'" which makes no sense for a variadic function
template.


live: https://godbolt.org/g/hvJh5F

Version info (-v output):

Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../gcc-4.6.4/configure --prefix /root/staging
--build=x86_64-linux-gnu --disable-multilibs --disable-bootstrap
--enable-clocale=gnu --enable-languages=c,c++ --enable-ld=yes --enable-gold=yes
--enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-linker-build-id
--enable-lto --enable-plugins --enable-threads=posix --host=x86_64-linux-gnu
--target=x86_64-linux-gnu --with-pkgversion=GCC-Explorer-Build MAKEINFO=missing

Thread model: posix
gcc version 4.6.4 (GCC-Explorer-Build)
COLLECT_GCC_OPTIONS='-g' '-o'
'/tmp/compiler-explorer-compiler117213-16078-toh8kw.p3gjt9be29/output.s'
'-masm=intel' '-S' '-std=c++0x' '-v' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'

GNU C++ (GCC-Explorer-Build) version 4.6.4 (x86_64-linux-gnu)
compiled by GNU C version 5.4.0 20160609, GMP version 4.3.2, MPFR version
2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072