* Use ref locals to simplify code flow
* Fix VB code layout

Some reference assemblies omit information about private fields. To
avoid treating structures in these assemblies as immutable, we only
consider types immutable if they contain information about one or more
private fields.

This is a workaround for issues like dotnet/standard#678.

Works around microsoft/vs-streamjsonrpc#272

* Ctor refactoring

* Renames

* Renames

* Cleanup

* ProjectExternalErrorReporter ctor

* Refactoring

* Remove dependency on VS

* Aggregation improvements

* Use ordinal comparer for project names

* Construct ProjectExternalErrorReporter lazily

* Fix off by one

* Fix issues

* Wip

* Update more pages

* Formatting

* Respond to feedback

* Add spacing to Formatting General page

* Get SVsSolution service instead of IVsSolution

* Use the correct GetService overload

this particular code path can take a long time if metadata reference hasn't created its symbols yet.

this can get really bad if we try to show code lens for something like IDispose.Dipose and it tries to create all metdata references in the solution.

since it is not cancellable, just passing by a Dipose method can cause this to occupy CPU 100% for several seconds and there is no way to make it go away.

now we pass in cancellation token so that we can bail out  sooner.

This change allows the PerformanceSensitiveAttribute to be applied to
the method. See dotnet/csharplang#1888.

This test is flaky in legacy completion, but legacy completion is slated
for removal so the test failures were not fully investigated.

Our CI machines don't have a new enough MSBuild to support this; adding
it is tracked by https://github.com/dotnet/core-eng/issues/6424 which
is currently underway but there's no reason to hold up the larger
work on the test.

* Write Roslyn assembly version to DependentAssemblyVersions file

* Depend on GetAssemblyVersion to ensure AssemblyVersion has been calculated

* Update implicity declared type expression nullability:
- When updating the implicit type in a declaration also update the bound type declaration nullability
- Record nullability for inferred foreach variable
- Add nullable public api tests
- Add nullable tests

* mark NFW from OOP critical

currently, whenever OOP throws an exception, we show infobar saying "restart VS". whenever that happens, we report NFW. now those NFW will be marked as critical and we will stop reporting NFW after that in VS.

basically making critical NFW behavior same as fatal watson in VS. and management will treat critical NFW same as fatal watson.

also, now we will show callstack like code fix exception when info bar is shown

* xml document fix

* fix build break.

* changed button to hyper-link to follow same pattern as other info bar (code fix)

show remote exception in callstack view.

* introduced enum for Watson Severity

* Learn from comparisons to non-constant, non-null values

* Update comment

* Remove unused local function

* Remove another unused local function

* Check for null constant before trying to learn from notNull == maybeNull. Add tests

* More tests, more cleanup

* Add conditional access with || test

* More test updates from feedback

* Cleanup

* Change some locals in tests to parameters

Update FindImplementationsForInterfaceMemberAsync to correctly handle ambiguous type returns (#35853)

FindImplementationsForInterfaceMemberAsync checks for forwarded types using SymbolFinder.OriginalSymbolsMatch, which expects non-null compilation for both the project containing the interface and the project containing the symbol to compare to. Until now, most instances have found equivalence without falling through, but in cases where the type forwarding isn't completely verified a non-null compilation for the interface symbol is needed as well. See VerifyForwardedTypes for the logic being used.

In #35786 the type System.Text.Encoding is provided by a a NuGet reference and could be ambiguous based on the build target. The OOP service attempts to find the correct type resolution but needs the original symbol compilation to verify.

Without this fix, FindAllReferences may cause a null deref and fail.

Fixes #35786

This change produced a 220MB (6.7%) allocation reduction in the scenario
described by #36158.

This makes the extension method work again. The workaround is tracked by
https://github.com/dotnet/roslyn/issues/36093.

This catches places we're calling Construct() or
ClassifyConversion().