Fix several issues with diagnostics

1. The diagnostics provider won't refresh diagnostics while the OmniSharp server is restoring packages. Instead, it
   waits until it receives an event from OmniSharp afterward. However, that event was only expecting the old DNX
   protocol, so the diagnostics provider never automatically updated after packages were restored. This change gets
   rid of the DNX protocol and changes the diagnostic provider to look for .NET Core projects.

2. Hidden diagnostics should have DiagnosticSeverity.Info rather DiagnosticSeverity.Warning.

3. When the processing *all* of the diagnostics (not just those for the current file), the previous diagnostics were
   not cleared out first. This resulted in new diagnostics being merged with old diagnostics, creating duplicates
   diagnostics. Now we clear the diagnostics for a file before adding new ones.

src/features/diagnosticsProvider.ts

@@ -43,8 +43,8 @@ export class Advisor {
 	}
 
 	private _onProjectChange(info: protocol.ProjectInformationResponse): void {
-		if (info.DnxProject && info.DnxProject.SourceFiles) {
-			this._projectSourceFileCounts[info.DnxProject.Path] = info.DnxProject.SourceFiles.length;
+		if (info.DotNetProject && info.DotNetProject.SourceFiles) {
+			this._projectSourceFileCounts[info.DotNetProject.Path] = info.DotNetProject.SourceFiles.length;
 		}
 		if (info.MsBuildProject && info.MsBuildProject.SourceFiles) {
 			this._projectSourceFileCounts[info.MsBuildProject.Path] = info.MsBuildProject.SourceFiles.length;
@@ -94,7 +94,7 @@ class DiagnosticsProvider extends AbstractSupport {
 	constructor(server: OmnisharpServer, validationAdvisor: Advisor) {
 		super(server);
 		this._validationAdvisor = validationAdvisor;
-		this._diagnostics = languages.createDiagnosticCollection('omnisharp');
+		this._diagnostics = languages.createDiagnosticCollection('csharp');
 
 		let d1 = this._server.onPackageRestore(this._validateProject, this);
 		let d2 = this._server.onProjectChange(this._validateProject, this);
@@ -108,9 +108,11 @@ class DiagnosticsProvider extends AbstractSupport {
 		if (this._projectValidation) {
 			this._projectValidation.dispose();
 		}
+
 		for (let key in this._documentValidations) {
 			this._documentValidations[key].dispose();
 		}
+
 		this._disposable.dispose();
 	}
 
@@ -153,9 +155,18 @@ class DiagnosticsProvider extends AbstractSupport {
 		let source = new CancellationTokenSource();
 		let handle = setTimeout(() => {
             serverUtils.codeCheck(this._server, { Filename: document.fileName }, source.token).then(value => {
+				// Easy case: If there are no diagnostics in the file, we can clear it quickly. 
+				if (value.QuickFixes.length === 0) {
+					if (this._diagnostics.has(document.uri)) {
+						this._diagnostics.delete(document.uri);
+					}
 
+					return;
+				}
+				
 				// (re)set new diagnostics for this document
 				let diagnostics = value.QuickFixes.map(DiagnosticsProvider._asDiagnostic);
+
 				this._diagnostics.set(document.uri, diagnostics);
 			});
 		}, 750);
@@ -190,11 +201,22 @@ class DiagnosticsProvider extends AbstractSupport {
 					if (lastEntry && lastEntry[0].toString() === uri.toString()) {
 						lastEntry[1].push(diag);
 					} else {
+						// We're replacing all diagnostics in this file. Pushing an entry with undefined for
+						// the diagnostics first ensures that the previous diagnostics for this file are
+						// cleared. Otherwise, new entries will be merged with the old ones.
+						entries.push([uri, undefined]);
 						lastEntry = [uri, [diag]];
 						entries.push(lastEntry);
 					}
 				}
 
+			    // Clear diagnostics for files that no longer have any diagnostics.
+				this._diagnostics.forEach((uri, diagnostics) => {
+					if (!entries.find(tuple => tuple[0] === uri)) {
+						this._diagnostics.delete(uri);
+					}
+				});
+
 				// replace all entries
 				this._diagnostics.set(entries);
 			});
@@ -216,10 +238,11 @@ class DiagnosticsProvider extends AbstractSupport {
 
 	private static _asDiagnosticSeverity(logLevel: string): DiagnosticSeverity {
 		switch (logLevel.toLowerCase()) {
-			case 'hidden':
 			case 'warning':
 			case 'warn':
 				return DiagnosticSeverity.Warning;
+			case 'hidden':
+				return DiagnosticSeverity.Information;
 			default:
 				return DiagnosticSeverity.Error;
 		}

src/features/status.ts

@@ -165,11 +165,8 @@ export function reportDocumentStatus(server: OmnisharpServer): vscode.Disposable
 					}
 				}
 
-				// show dnx projects if applicable
-                if ('Dnx' in info) {
-                    addDnxOrDotNetProjects(info.Dnx.Projects);
-                }
-                else if ('DotNet' in info) {
+				// show .NET Core projects if applicable
+                if ('DotNet' in info) {
                     addDnxOrDotNetProjects(info.DotNet.Projects);
                 }
 

src/omnisharp/protocol.ts

@@ -212,12 +212,11 @@ export interface AutoCompleteResponse {
 
 export interface ProjectInformationResponse {
     MsBuildProject: MSBuildProject;
-    DnxProject: DnxProject;
+    DotNetProject: DotNetProject;
 }
 
 export interface WorkspaceInformationResponse {
     MsBuild: MsBuildWorkspaceInformation;
-    Dnx: DnxWorkspaceInformation;
     DotNet: DotNetWorkspaceInformation;
     ScriptCs: ScriptCsContext;
 }
@@ -244,29 +243,6 @@ export interface MSBuildProject {
     SourceFiles: string[];
 }
 
-export interface DnxWorkspaceInformation {
-    RuntimePath: string;
-    DesignTimeHostPort: number;
-    Projects: DnxProject[];
-}
-
-export interface DnxProject {
-    Path: string;
-    Name: string;
-    Commands: { [name: string]: string; };
-    Configurations: string[];
-    ProjectSearchPaths: string[];
-    Frameworks: DnxFramework[];
-    GlobalJsonPath: string;
-    SourceFiles: string[];
-}
-
-export interface DnxFramework {
-    Name: string;
-    FriendlyName: string;
-    ShortName: string;
-}
-
 export interface DotNetWorkspaceInformation {
     Projects: DotNetProject[];
     RuntimePath: string;