When I managed to get my class library running under NCrunch earlier I had a test failure and right-clicked a line in the class that was under test and opted to break into the first failing test on that line.

There were no named locals in the locals pane of Visual Studio, hovering over variables didn't work, quickwatch/quick evaluate did not work.

Could it be that compiler output has changed so that the instrumentation engine that handles code coverage and timing is no longer entirely compatible with it?

I can help with that.

Clone/download this project:

https://github.com/lassevk/DiffLib

changeset 026ab3773fe473adaa8339b29fb786aef3aeabcf

Go to the Diff.cs file, line 74 (int matchStart = ...). Right-click the indicator for this line (after NCrunch has warmed up) then pick "Break into first covering test".

I have the following locals:

this
slice1
slice2
(11 unnamed ones of bool and int types)
instrumentationExistingCoverageMarkedIndex
instrumentationExistingTickCount
instrumentationReturnValue
Type Variables -> T

There should be a lot of locals in that method, like matchStart, subslice1, subslice2, matchEnd, but they all seems to be missing. Note that subslice1 and subslice2 are of type Slice<char>, so they are not in the unnamed ones either.

Sorry, it doesn't look like I will be able to provide you with a fix for this issue in the short term.

On close analysis of the method, there does not appear to be any debug metadata being misinterpreted by NCrunch. Somehow, the variables are being swallowed. I've had no luck in reproducing the problem outside the method that you've provided.

I recommend breaking the method down in order to reduce its complexity - this may help with the debug resolution. I will continue trying to understand why this is behaving the way it is. I do not think this is a new problem introduced by VS2015 RTM - it's likely been there for a while.