Refuse to create an empty data pack

This avoids a segfault from trying to access te front element of an
empty list.

diff --git a/source/datatool.cpp b/source/datatool.cpp
index ca2f2e49aaef3738cd2bf2c12171af03d902c746..d23c00de00f8531898c7278d50db78730e88ddc0 100644 (file)
--- a/source/datatool.cpp
+++ b/source/datatool.cpp
@@ -37,6 +37,8 @@ Target *DataTool::create_target(const list<Target *> &sources, const string &arg
        }
        else if(arg=="pack")
        {
+               if(sources.empty())
+                       throw invalid_argument("DataTool::create_target");
                list<FileTarget *> files;
                for(Target *t: sources)
                        files.push_back(&dynamic_cast<FileTarget &>(*t));