diff --git a/triqs/gfs/re_im_freq.hpp b/triqs/gfs/re_im_freq.hpp
index 5563b80e..2d596d29 100644
--- a/triqs/gfs/re_im_freq.hpp
+++ b/triqs/gfs/re_im_freq.hpp
@@ -35,6 +35,7 @@ namespace triqs { namespace gfs {
    typedef gf_mesh<refreq,Opt> m1_t; 
    typedef gf_mesh<imfreq,Opt> m2_t; 
    typedef mesh_product<m1_t,m2_t> B;
+   gf_mesh () = default;
    gf_mesh (double wmin, double wmax, size_t n_freq_re, double beta, statistic_enum S, size_t n_freq_im) :
     B { gf_mesh<refreq,Opt>(wmin,wmax,n_freq_re,full_bins), gf_mesh<imfreq,Opt>(beta, S, n_freq_im)} {}
   };
diff --git a/triqs/gfs/re_im_time.hpp b/triqs/gfs/re_im_time.hpp
index d44dbaa0..49970cb6 100644
--- a/triqs/gfs/re_im_time.hpp
+++ b/triqs/gfs/re_im_time.hpp
@@ -35,6 +35,7 @@ namespace triqs { namespace gfs {
   typedef gf_mesh<retime,Opt> m1_t; 
   typedef gf_mesh<imtime,Opt> m2_t; 
   typedef mesh_product<m1_t,m2_t> B;
+  gf_mesh () = default;
   gf_mesh (double tmin, double tmax, size_t nt, double beta, statistic_enum S, size_t ntau, mesh_kind mk=full_bins) :
    B {gf_mesh<retime,Opt>(tmin,tmax,nt), gf_mesh<imtime,Opt>(beta,S, ntau, mk)} {}
  };
diff --git a/triqs/gfs/refreq_imtime.hpp b/triqs/gfs/refreq_imtime.hpp
index 357fd8e2..6639c56f 100644
--- a/triqs/gfs/refreq_imtime.hpp
+++ b/triqs/gfs/refreq_imtime.hpp
@@ -35,6 +35,8 @@ namespace triqs { namespace gfs {
   typedef gf_mesh<refreq,Opt> m1_t; 
   typedef gf_mesh<imtime,Opt> m2_t; 
   typedef mesh_product<m1_t,m2_t> B;
+  gf_mesh () = default;
+  gf_mesh(B const & x) : B(x) {}
   gf_mesh (double wmin, double wmax, size_t n_freq, double beta, statistic_enum S, size_t nt, mesh_kind mk=full_bins ) :
    B {gf_mesh<refreq,Opt>(wmin,wmax,n_freq), gf_mesh<imtime,Opt>(beta,S,nt,mk)} {}
  };
diff --git a/triqs/gfs/two_real_times.hpp b/triqs/gfs/two_real_times.hpp
index 9bd7b926..8caeeef0 100644
--- a/triqs/gfs/two_real_times.hpp
+++ b/triqs/gfs/two_real_times.hpp
@@ -101,7 +101,7 @@ namespace triqs { namespace gfs {
    
    static gf_t make_gf(double tmax, double n_time_slices) {
     auto m =  gf_mesh<two_real_times,Opt>(tmax, n_time_slices);
-    typename gf_t::data_non_view_t A(m.size()); A() =0;
+    typename gf_t::data_regular_t A(m.size()); A() =0;
     return gf_t (m, std::move(A), nothing(), nothing() ) ;
    }
   };
@@ -112,7 +112,7 @@ namespace triqs { namespace gfs {
  
  // from g(t,t') and t, return g(t-t') for any t'>t 
  // 
- gf<retime> slice (gf_view<two_real_times> const & g, double t) { 
+ inline gf<retime> slice (gf_view<two_real_times> const & g, double t) { 
   auto const & m = std::get<0> (g.mesh().components());   //one-time mesh
   long it = get_closest_mesh_pt_index(m, t);              //index of t on this mesh
   long nt = m.size() - it;