[Bug c++/58328] New: [C++11] bogus: error: constructor required before non-static data member for

[Bug c++/58328] New: [C++11] bogus: error: constructor required before non-static data member for

[ppluzhnikov at google dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58328

            Bug ID: 58328
           Summary: [C++11] bogus: error: constructor required before
                    non-static data member for
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ppluzhnikov at google dot com

Google ref: b/10634418

This appears to be very similar to PR 57770

Using g++ (GCC) 4.9.0 20130904 (experimental)

cat t.cc

struct A {
  struct B {
    // B() {}  // Uncommenting this line makes it work.
    int y = 1; // Removing initializer makes it work.
  };

  A(const B& opts = B()) {}  // Removing default makes it work.
};


g++ -c t.cc -std=c++11
t.cc: In constructor 'A::B::B()':
t.cc:2:10: error: constructor required before non-static data member for
'A::B::y' has been parsed
   struct B {
          ^
t.cc: At global scope:
t.cc:7:23: note: synthesized method 'A::B::B()' first required here 
   A(const B& opts = B()) {}
                       ^

[Bug c++/58328] [C++11] bogus: error: constructor required before non-static data member for

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58328

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
I suspect the error isn't bogus, current clang++ also rejects it.

[Bug c++/58328] [C++11] bogus: error: constructor required before non-static data member for

[ppluzhnikov at google dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58328

--- Comment #2 from Paul Pluzhnikov <ppluzhnikov at google dot com> ---
(In reply to Paolo Carlini from comment #1)
> I suspect the error isn't bogus, current clang++ also rejects it.

Hmm, perhaps you are correct. The original test that is *not* rejected by clang
was:

struct A {
  struct B {
    int x, y = 1;
  };

  A(const B& opts = B()) {}
};

But perhaps Clang doesn't reject it in error?

[Bug c++/58328] [C++11] bogus: error: constructor required before non-static data member for

[richard-gccbugzilla at metafoo dot co.uk]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58328

Richard Smith <richard-gccbugzilla at metafoo dot co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |richard-gccbugzilla@metafoo
                   |                            |.co.uk

--- Comment #3 from Richard Smith <richard-gccbugzilla at metafoo dot co.uk> ---
This is in the area of a core language defect, and IIRC CWG hasn't really
decided which cases should be valid. Clang accepts the code in comment#2 but
rejects the code in comment#0 because, in comment#0, 'A::B::B()' is constexpr,
so Clang triggers the computation of the implicit exception specification of
'A::B::B()' earlier (before the default initializer for 'A::B::y' is parsed).

It seems that g++ more eagerly computes the exception specification for
'A::B::B()'. That seems more in line with the resolution of core issue 1330,
which suggests to me that we should trigger the computation of the exception
specification when we parse the 'B()' expression, so I'm inclined to say that
Clang is in error in accepting the code in comment#2.

[Bug c++/58328] [C++11] bogus: error: constructor required before non-static data member for

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58328

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Thus, I'm going to add to the testsuite both testcases as ill-formed and
closing the bug.

[Bug c++/58328] [C++11] bogus: error: constructor required before non-static data member for

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58328

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #6 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Done.