through IDynamicFileInfoProvider and etc, external component such as razor should be able to provide us dynamic file (such as generated c# content for cshtml file) on the fly and let us know update on the content.

renamed Column to Character since Column should be only used when it accounts "tab". and count "tab" as tab size rather than just 1 char.

moved FAR to work on top of new set of APIs. it should now show things on html correctly

added support for code lens. but found 1 issue. without changing VS side, I can't fix filename. and without fixing filename, navigation won't work properly

We might disconnect/reconnect on background threads now, so
be ready for that.

The underlying process of removing a document already handled this,
this was an unnecessary block. It was already the case that you could
call OnProjectRemoved to remove the entire project that had open files,
so this didn't really avoid badness in the first place.

Added AddMissingImport CodeRefactoring driven by PasteTrackingService

Added PasteTrackingService that handles the paste command and track
paste information for documents. This paste information can be used
by refactorings to make suggestions based on what was pasted.

Fixes #10272

Add an explanatory comment and revert the semantics of the new TestParameters flag so the default value (false) retains the current semantics.

Enable testing non-fixable diagnostics in the test framework. Current implementation filters out all non-fixable diagnostics completely.

* Move Index from unary operators to a stand alone node

* Remove indexer hack

* Remove prototype comments

* Testing/fixing IDE services

* Added EE tests

* Rename "Index" nodes to "FromEndIndex"

* More comments

* Some minor fixups and test fixes

For cases where the requested span is (x, x), try using span
intersection rather than contains.

That should cover all the cases for requesting the diagnostics
at caret

Fixes #27703

Also fix the IDE helper to get value usage info, which fixes the MakeFieldReadOnlyAnalyzer

Fixes #29373
Fixes #30175

The addition of IThreadingContext to this type's constructor broke
TypeScript, which they already have a build for that deals with the
change. However it requires a simultaneous insertion which is proving
difficult to achieve. Adding this overload (which is admittedly a total
hack) allows TypeScript to continue functioning even with Roslyn's
change.

Conservatively apply logical not operator to an expression being negated if it is not a binary operation.

Fixes #29434

We were basically missing
https://github.com/dotnet/roslyn/commit/83bc0861a947b7bf5d8056c2366bf441b23b6f16

1. Bail out for explicit interface implementations for properties, we only did so for methods.
2. Bail out for types with StructLayoutAttribute
3. Conservatively handle member references inside DebuggerDisplayAttribute argument by doing a simple string contains check.

Address PR feedback (use static ctor and remove regions) and also fix an assert seen during dogfooding.

Primarily addresses https://github.com/dotnet/roslyn/issues/29519#issuecomment-420067012

```
1. Enable the rules be default
2. Remove all the workaround/hacks for disabling the rules for product and enabling for tests.
3. Address offline feedback from @sharwell about avoiding deriving the tests from `TestBase`.
4. Separate out the pending non-design related work items from first comment into separate issues.
```

For 4., I have repurposed https://github.com/dotnet/roslyn/issues/29519 to track the pending issues with checkboxes in the first issue comment.

* Move xunit package references to Roslyn.Toolsets.Xunit.targets

* Remove dependency on Microsoft.NET.Test.Sdk

This method is only recursive in one limited scenario, which is now
specially handled to avoid the need to track a visited set.