Bootstrap failure in libstdc++-v3 on GNU/Linux x86

[Florian Weimer]

I get a very obscure bootstrap failure for mainline:

In file included from /home/fw/src/gnu/gcc/libstdc++-v3/src/complex_io.cc:30:
/tmp/gcc/i686-pc-linux-gnu/libstdc++-v3/include/complex: In member function `long double& std::complex<long double>::real()':
/tmp/gcc/i686-pc-linux-gnu/libstdc++-v3/include/complex:1296: error: invalid initialization of reference of type 'long double&' from expression of type 'long int'
/tmp/gcc/i686-pc-linux-gnu/libstdc++-v3/include/complex: In member function `long double& std::complex<long double>::imag()':
/tmp/gcc/i686-pc-linux-gnu/libstdc++-v3/include/complex:1304: error: invalid initialization of reference of type 'long double&' from expression of type 'long int'

This doesn't make sense because the member function in question reads:

  inline long double&
  complex<long double>::real()
  { return __real__ _M_value; }                   // line 1296

And _M_value does have type __complex__ long double.  Should I start a
binary search, or is this known to be some kind of recent breakage?