[Bug c++/61683] New: decltype-specifier not accepted as mem-initializer-id

[bbi5291 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61683

            Bug ID: 61683
           Summary: decltype-specifier not accepted as mem-initializer-id
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bbi5291 at gmail dot com

$ cat main.cpp
struct A {};
A a;
struct B : A {
    B(): decltype(a)() {}
};
int main() {}

$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ./configure --program-suffix=-4.9.0
Thread model: posix
gcc version 4.9.0 (GCC) 

$ g++-4.9.0 -std=c++11 main.cpp
main.cpp: In constructor ‘B::B()’:
main.cpp:4:10: error: expected identifier before ‘decltype’
     B(): decltype(a)() {}
          ^
main.cpp:4:10: error: expected ‘{’ before ‘decltype’

--

This code should compile because the standard says that any class-or-decltype
that denotes a base class can be used in a mem-initializer-list.

clang accepts: http://coliru.stacked-crooked.com/a/b50333efbcab9d26