internal/lsp: display current diagnostics in the debug server

The change displays outstanding diagnostics on the Client page of
the debug server.

Very occasionally gopls displays incorrect diagnostics or diagnositics
that won't go away.  It is possible that providing more complete
information will help us find the causes, at least when the debug
server is running.

Change-Id: I01f2bbbfeac86e7296f57f4a9aad8e1e658babfa
Reviewed-on: https://go-review.googlesource.com/c/tools/+/285252
Run-TryBot: Peter Weinberger <pjw@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Peter Weinberger <pjw@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>

internal/lsp/debug/serve.go

@@ -181,6 +181,7 @@ type Client struct {
 	Logfile      string
 	GoplsPath    string
 	ServerID     string
+	Service      protocol.Server
 }
 
 // A Server is an outgoing connection to a remote LSP server.
@@ -314,6 +315,16 @@ func (i *Instance) getInfo(r *http.Request) interface{} {
 	return template.HTML(buf.String())
 }
 
+func (i *Instance) AddService(s protocol.Server, session *cache.Session) {
+	for _, c := range i.State.clients {
+		if c.Session == session {
+			c.Service = s
+			return
+		}
+	}
+	stdlog.Printf("unable to find a Client to add the protocol.Server to")
+}
+
 func getMemory(r *http.Request) interface{} {
 	var m runtime.MemStats
 	runtime.ReadMemStats(&m)
@@ -785,6 +796,29 @@ Using session: <b>{{template "sessionlink" .Session.ID}}</b><br>
 {{if .DebugAddress}}Debug this client at: <a href="http://{{localAddress .DebugAddress}}">{{localAddress .DebugAddress}}</a><br>{{end}}
 Logfile: {{.Logfile}}<br>
 Gopls Path: {{.GoplsPath}}<br>
+<h2>Diagnostics</h2>
+{{/*Service: []protocol.Server; each server has map[uri]fileReports;
+	each fileReport: map[diagnosticSoure]diagnosticReport
+	diagnosticSource is one of 5 source
+	diagnosticReport: snapshotID and map[hash]*source.Diagnostic
+	sourceDiagnostic: struct {
+		Range    protocol.Range
+		Message  string
+		Source   string
+		Code     string
+		CodeHref string
+		Severity protocol.DiagnosticSeverity
+		Tags     []protocol.DiagnosticTag
+
+		Related []RelatedInformation
+	}
+	RelatedInformation: struct {
+		URI     span.URI
+		Range   protocol.Range
+		Message string
+	}
+	*/}}
+<ul>{{range $k, $v := .Service.Diagnostics}}<li>{{$k}}:<ol>{{range $v}}<li>{{.}}</li>{{end}}</ol></li>{{end}}</ul>
 {{end}}
 `))
 

internal/lsp/diagnostics.go

@@ -50,6 +50,23 @@ type fileReports struct {
 	reports       map[diagnosticSource]diagnosticReport
 }
 
+func (d diagnosticSource) String() string {
+	switch d {
+	case modSource:
+		return "FromSource"
+	case gcDetailsSource:
+		return "FromGCDetails"
+	case analysisSource:
+		return "FromAnalysis"
+	case typeCheckSource:
+		return "FromTypeChecking"
+	case orphanedSource:
+		return "FromOrphans"
+	default:
+		return fmt.Sprintf("From?%d?", d)
+	}
+}
+
 // hashDiagnostics computes a hash to identify diags.
 func hashDiagnostics(diags ...*source.Diagnostic) string {
 	source.SortDiagnostics(diags)
@@ -546,3 +563,34 @@ func (s *Server) shouldIgnoreError(ctx context.Context, snapshot source.Snapshot
 	})
 	return !hasGo
 }
+
+// Diagnostics formattedfor the debug server
+// (all the relevant fields of Server are private)
+// (The alternative is to export them)
+func (s *Server) Diagnostics() map[string][]string {
+	ans := make(map[string][]string)
+	s.diagnosticsMu.Lock()
+	defer s.diagnosticsMu.Unlock()
+	for k, v := range s.diagnostics {
+		fn := k.Filename()
+		for typ, d := range v.reports {
+			if len(d.diags) == 0 {
+				continue
+			}
+			for _, dx := range d.diags {
+				ans[fn] = append(ans[fn], auxStr(dx, d, typ))
+			}
+		}
+	}
+	return ans
+}
+
+func auxStr(v *source.Diagnostic, d diagnosticReport, typ diagnosticSource) string {
+	// Tags? RelatedInformation?
+	msg := fmt.Sprintf("(%s)%q(source:%q,code:%q,severity:%s,snapshot:%d,type:%s)",
+		v.Range, v.Message, v.Source, v.Code, v.Severity, d.snapshotID, typ)
+	for _, r := range v.Related {
+		msg += fmt.Sprintf(" [%s:%s,%q]", r.URI.Filename(), r.Range, r.Message)
+	}
+	return msg
+}

internal/lsp/lsprpc/lsprpc.go

@@ -61,6 +61,7 @@ func (s *StreamServer) ServeStream(ctx context.Context, conn jsonrpc2.Conn) erro
 	server := s.serverForTest
 	if server == nil {
 		server = lsp.NewServer(session, client)
+		debug.GetInstance(ctx).AddService(server, session)
 	}
 	// Clients may or may not send a shutdown message. Make sure the server is
 	// shut down.