[LyX/master] Do not return a reference to a temporary variable

[Jean-Marc Lasgouttes]

commit 5453e00cfa1f4974301f42ad238884b9ec7e7564
Author: Jean-Marc Lasgouttes <lasgout...@lyx.org>
Date:   Wed Mar 1 17:35:05 2017 +0100

    Do not return a reference to a temporary variable
    
    Coverity correctly spotted that the existing code creates a temporary
    map and returns a value from it. It is not possible to make the map
    const& directly because operator[] may change the map.
    
    Therefore, we use map::find instead.
---
 src/BufferParams.cpp |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/BufferParams.cpp b/src/BufferParams.cpp
index 4cbf227..f20078b 100644
--- a/src/BufferParams.cpp
+++ b/src/BufferParams.cpp
@@ -3305,8 +3305,12 @@ bool BufferParams::addCiteEngine(vector<string> const & 
engine)
 
 string const & BufferParams::defaultBiblioStyle() const
 {
-       map<string, string> bs = documentClass().defaultBiblioStyle();
-       return bs[theCiteEnginesList.getTypeAsString(citeEngineType())];
+       map<string, string> const & bs = documentClass().defaultBiblioStyle();
+       auto cit = 
bs.find(theCiteEnginesList.getTypeAsString(citeEngineType()));
+       if (cit != bs.end())
+               return cit->second;
+       else
+               return empty_string();
 }