The updated version no longer relies on solution file. It should not be looking there at all. We did add a new def-var that will allow you to override, which is off by default. On the SlickEdit command-line you can use:
set-var def_use_visual_studio_version 14
That should pick the Visual Studio 2015 toolset for building if devenv is not already found on PATH. The updated version by default uses the following search:
1) If devenv is found in PATH, use the that version.
2) If def_use_visual_studio_version is set to non-zero use the toolset version specified (14 is Visual Studio 2015, 12 -> Visual Studio 2013, 11 -> Visual Studio 2012, 10 -> Visual Studio 2010).
3) Search vcxproj files for PlatformToolset.
4) Use latest installed version of Visual Studio.
We also added an additional macro variable that sets the order of tests: def_auto_visual_studio_select. This is a comma delimited string, and defaults to: project,latest,solution,prompt.
After checking PATH and def_use_visual_studio_version, it will use the checks defined in def_use_visual_studio_version.
project: Search vcxproj files for PlatformToolset setting.
latest: Use latest installed version of Visual Studio.
solution: Use version specified in .sln file (same method from)
prompt: Select version from installed versions of Visual Studio (new command: vstudio_select_environment)
You can re-order the tests in with this def-var, in case some would rather have it check solution first. You would probably be best suited to use the def_use_visual_studio_version and just set it to the version you want.