[Bug c++/61122] New: too many initializers

[Bug c++/61122] New: too many initializers

[f.heckenbach@fh-soft.de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61122

            Bug ID: 61122
           Summary: too many initializers
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: f.heckenbach@fh-soft.de

g++ says "too many initializers" for an array of vectors with initializers, but
only within a struct.

Not sure if it should work (I don't see why not), but it seems inconsistent
that it only fails within a struct. Also, the error message is misleading ("too
many initializers" even for an empty brace-list).

#include <vector>

std::vector <int> a1[] { { } };
std::vector <int> a2[] { { 1, 2, 3 } };
std::vector <int> a3[] { std::vector <int> () };
std::vector <int> a4[] { std::vector <int> (1) };

struct s
{
  std::vector <int> b1[] { { } };
  std::vector <int> b2[] { { 1, 2, 3 } };
  std::vector <int> b3[] { std::vector <int> () };
  std::vector <int> b4[] { std::vector <int> (1) };
};

% g++ -std=c++11 test.cpp
test.cpp:10:32: error: too many initializers for 'std::vector<int> [0]'
test.cpp:11:40: error: too many initializers for 'std::vector<int> [0]'
test.cpp:12:49: error: too many initializers for 'std::vector<int> [0]'
test.cpp:13:50: error: too many initializers for 'std::vector<int> [0]'

[Bug c++/61122] "too many initializers" for NSDMI for array of unknown bound

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61122

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-05-09
            Summary|too many initializers       |"too many initializers" for
                   |                            |NSDMI for array of unknown
                   |                            |bound
     Ever confirmed|0                           |1

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I don't think you can specify an array bound from an NSDMI, but the diagnostic
is not very helpful.

[Bug c++/61122] "too many initializers" for NSDMI for array of unknown bound

[f.heckenbach@fh-soft.de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61122

--- Comment #2 from Frank Heckenbach <f.heckenbach@fh-soft.de> ---
If it's not allowed, it should also fail at file-scope or function-scope,
shouldn't it?

[Bug c++/61122] "too many initializers" for NSDMI for array of unknown bound

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61122

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
No. At file or function scope the initializer is definitely used, and can
provide the array bound.  On a non-static data member it is not used until the
object is constructed (and then might be ignored if there's a mem-initializer
for the member) and that's too late, the array bound for non-static data
members must be known at class definition time to know sizeof(s).

That's my understanding, and I've just checked clang agrees, with a better
diagnostic:


in.cc:10:26: error: array bound cannot be deduced from an in-class initializer
  std::vector <int> b1[] { { } };
                         ^
in.cc:11:26: error: array bound cannot be deduced from an in-class initializer
  std::vector <int> b2[] { { 1, 2, 3 } };
                         ^
in.cc:12:26: error: array bound cannot be deduced from an in-class initializer
  std::vector <int> b3[] { std::vector <int> () };
                         ^
in.cc:13:26: error: array bound cannot be deduced from an in-class initializer
  std::vector <int> b4[] { std::vector <int> (1) };
                         ^
4 errors generated.