From c8be00405539d8a202406939e159426fe7a7b2ad Mon Sep 17 00:00:00 2001
From: Olivier Parcollet <olivier.parcollet@cea.fr>
Date: Mon, 23 Jun 2014 16:13:27 +0200
Subject: [PATCH] gf : bug correction in make_block_gf

- See comment : a move + undefined order of args eval. of function
  error.
---
 triqs/gfs/block.hpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/triqs/gfs/block.hpp b/triqs/gfs/block.hpp
index cd36b724..415983c3 100644
--- a/triqs/gfs/block.hpp
+++ b/triqs/gfs/block.hpp
@@ -103,7 +103,8 @@ namespace gfs {
  // from a vector of gf (moving directly)
  template <typename Variable, typename Target, typename Opt>
  block_gf<Variable, Target, Opt> make_block_gf(std::vector<gf<Variable, Target, Opt>> V) {
-  return {{int(V.size())}, std::move(V), nothing{}, nothing{}, nothing{}};
+  int s = V.size(); // DO NOT use V.size in next statement, the V is moved and the order of arg. evaluation is undefined.
+  return {{s}, std::move(V), nothing{}, nothing{}, nothing{}};
  }
 
  // from a vector of gf : generalized to have a different type of gf in the vector (e.g. views...)
@@ -154,7 +155,8 @@ namespace gfs {
  }
 
  template <typename GF> gf_view<block_index, typename GF::regular_type> make_block_gf_view_from_vector(std::vector<GF> V) {
-  return {{int(V.size())}, std::move(V), nothing{}, nothing{}, nothing{}};
+  int s = V.size();
+  return {{s}, std::move(V), nothing{}, nothing{}, nothing{}};
  }
 
  template <typename GF>