The Visual Studio Tools for Unity are able to convert .NET debug symbol files (namely pdb files) to debug symbols files that are understood by Unity's scripting engine (namely .dll.mdb files) when importing both the .dll and the .pdb in the Assets folder.
If you prefer to handle the conversion yourself you need to call a tool named pdb2mdb on the .dll associated with the .pdb:
Will produce a MyLibrary.dll.mdb usable on Unity if MyLibrary.pdb is present.
The .pdb files generated by Visual Studio 2015 can contain new informations that are not handled by the pdb2mdb file shipped by Unity.
You can download below the version that VSTU is using which handles the new 2015 format. This executable is self-contained and embeds all the references it needs, namely Mono.Cecil.
- pdb2mdb is licensed under the Microsoft Public License (Ms-PL).
- Mono.Cecil is licensed under the MIT/X11.