[Bug c++/57566] New: [C++11][constexpr] static temporaries bound recursively in reference constant expressions don't get initialized

[richard-gccbugzilla at metafoo dot co.uk]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57566

            Bug ID: 57566
           Summary: [C++11][constexpr] static temporaries bound
                    recursively in reference constant expressions don't
                    get initialized
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: richard-gccbugzilla at metafoo dot co.uk

If a temporary is lifetime-extended by being bound to a reference within a
lifetime-extended temporary, and the complete initializer is a constant
expression, the outer temporary does not get initialized and the inner
temporary does not get emitted. Example:

struct S { int &&a; int b; };
S &&s = { 123, 456 };

GCC emits:

        .local  _ZGR1s0
        .comm   _ZGR1s0,16,16
        .globl  s
        .bss
        .align 8
        .type   s, @object
        .size   s, 8
s:
        .zero   8

GCC emits code to dynamically initialize 's.a' to the address of _ZGR1s0. GCC
does not emit any code to initialize _ZGR1s0 itself, nor to initialize s.b.

Both s and the temporaries should be emitted as constants.