C#: Change TrapStackBehaviour of local functions

[tamasvajk]

Differences job: https://jenkins.internal.semmle.com/job/Changes/job/CSharp-Differences/451/

[tamasvajk]

I ran the following query on the before and after snapshots of roslyn.

  private predicate testExpr(Expr e, LocalFunction lf) {
    e.getEnclosingCallable() = lf and
    not exists(lf.getALocation())
  }

The before one returns 40369 results. The after one returns 0.

The following query returns 4 (2 duplicated) expressions in the before snapshot:

  private predicate test(Expr e) {
    e.getLocation().getStartLine() = 35 and
    e.getFile().getStem() = "CommandLineTestBase"
  }

And the same query correctly returns only 2 expressions in the after snapshot.

[tamasvajk]

I have no clue how to add a test case for this issue.

[hvitved]

Excellent. I checked that we didn't get any "TagStack unexpectedly empty" errors in the csharp.log files of dotnet/roslyn and dotnet/runtime.