How to debug into .NET framework source code

Question

How can one debug the .NET framework source code using Visual Studio 2017?

There are some questions here on stackoverflow about this topic, but

Answer 1

Many people wondering why they can't step into source although they does set the checkboxes as described above. I'm, too.

Because you can extract dotnet sources to any location, Visual Studio isn't able to know about them and the reason can't be the source files itself (why Visual Studio doesn't find the files).

But some dll's are browseable, some not (through double clicking in Visual Studios stack view or context menu > goto source). This brought me to the assumption, that the .pdb itself must be the reason. If you look into a file which works (e.g. notepad), you see at beginning a list of strings with file pathes (source files). In files, which doesn't work, the files starting immediatelly with binary data.

For some reason microsoft doesn't create her .pdb's with full debug information in every build process. But why not - good question! g

In short: you have to search a dll version of your file (which you like to debug) which contains FULL DEBUG INFORMATION. This is also the reason why context menu disables "goto source". I'm replacing this file temporary in global assembly cache for time of debug. This works for me.

Here an example of PresentationFramework.dll - 4.0.30319.298 => pdb size: 1219 KB - 4.0.30319.18408 => pdb size: 15.562 KB

Perhabs somebody can create a public database (wiki), which everyone can add files and versions for which full debug information are available?