Fixes https://dev.azure.com/devdiv/DevDiv/_workitems/edit/2641964.

StringTokenMap (added in dotnet#78033)
used reference equality comparer; I believe by mistake; which
made it possible for it to contain the same string multiple times;
leading to overflowing the user string heap limit sooner than before.

…sibility of declared extension method (dotnet#81378)

Due to an oversight it was compared to accessibility of extension block
container, which is always `public`.

Fixes dotnet#81180

Relates to test plan dotnet#76130

Fixes dotnet#16595
Fixes dotnet#4009

…ent (dotnet#81393)

Co-authored-by: CyrusNajmabadi <4564579+CyrusNajmabadi@users.noreply.github.com>

[main] Update dependencies from dotnet/arcade

[main] Update dependencies from dotnet/arcade

Part of dotnet/razor#12491

…eyword-event-handler

Co-authored-by: CyrusNajmabadi <4564579+CyrusNajmabadi@users.noreply.github.com>

…hub.com/dotnet/roslyn into copilot/fix-await-keyword-event-handler

Co-authored-by: CyrusNajmabadi <4564579+CyrusNajmabadi@users.noreply.github.com>

Co-authored-by: CyrusNajmabadi <4564579+CyrusNajmabadi@users.noreply.github.com>

Co-authored-by: CyrusNajmabadi <4564579+CyrusNajmabadi@users.noreply.github.com>

Followup to dotnet#81393.

I am proposing fixes for two LSP conformance issues I discovered while
integrating Roslyn LSP with Zed:

1. The response from the `textDocument/diagnostic` request cannot be
`null`. MS.CA.LanguageServer currently returns a `null` response in the
case described here:
https://github.com/dotnet/roslyn/blob/76a39c1a97fe5c73549786fc6944dc188a7b7b3b/src/LanguageServer/Protocol/Handler/Diagnostics/DiagnosticSourceProviders/DiagnosticSourceManager.cs#L72-L80
Because the set of diagnostic handlers is empty, a response value is
never generated for the request, and we fall through to returning
`null`. Instead, explicitly return an empty list of diagnostics. (This
is exactly how VS Code's LSP client treats a `null` response.)

2. Methods that take no parameters (e.g. `workspace/diagnostic/refresh`)
were being sent with an empty array as the parameter value. This is
because the `InvokeWithCancellationAsync` method in StreamJsonRpc
normalizes unspecified arguments to an empty list. Use the
`InvokeParameterObjectAsync` method instead, which don't do this.

…eyword-event-handler

…terGoToDef

…dates. (dotnet#81583)

…spaces.MSBuild.BuildHost (dotnet#81562)

…ions (dotnet#81569)

Language rules around conversions are getting more and more complex. At
the same time Convert APIs in SyntheticBoundNodeFactory might confuse
consumer into thinking that they are able to synthesize nodes for
arbitrary conversions, which is not the case.

This change removes one API and adds an assert to remaining API to
verify that only conversions that are natively supported by Emit layer
are coming through.