Support syntactic diagnostics in partial mode (#44859)

* Initial work to support syntactic diagnostics in partial mode.

* Test out 'syntacticDiagnosticsSync' requests.

* Added a 'geterr' test.

* Accepted baselines.

* Remove/clean up comments.

Author: DanielRosenwasser

src/server/session.ts

@@ -629,9 +629,7 @@ namespace ts.server {
         CommandNames.CompilerOptionsDiagnosticsFull,
         CommandNames.EncodedSemanticClassificationsFull,
         CommandNames.SemanticDiagnosticsSync,
-        CommandNames.SyntacticDiagnosticsSync,
         CommandNames.SuggestionDiagnosticsSync,
-        CommandNames.Geterr,
         CommandNames.GeterrForProject,
         CommandNames.Reload,
         CommandNames.ReloadProjects,
@@ -1055,7 +1053,7 @@ namespace ts.server {
 
                 const { fileName, project } = item;
 
-                // Ensure the project is upto date before checking if this file is present in the project
+                // Ensure the project is up to date before checking if this file is present in the project.
                 updateProjectIfDirty(project);
                 if (!project.containsFile(fileName, requireOpen)) {
                     return;
@@ -1066,6 +1064,11 @@ namespace ts.server {
                     return;
                 }
 
+                // Don't provide semantic diagnostics unless we're in full semantic mode.
+                if (project.projectService.serverMode !== LanguageServiceMode.Semantic) {
+                    goNext();
+                    return;
+                }
                 next.immediate(() => {
                     this.semanticCheck(fileName, project);
                     if (this.changeSeq !== seq) {
@@ -1074,13 +1077,12 @@ namespace ts.server {
 
                     if (this.getPreferences(fileName).disableSuggestions) {
                         goNext();
+                        return;
                     }
-                    else {
-                        next.immediate(() => {
-                            this.suggestionCheck(fileName, project);
-                            goNext();
-                        });
-                    }
+                    next.immediate(() => {
+                        this.suggestionCheck(fileName, project);
+                        goNext();
+                    });
                 });
             };
 

src/services/services.ts

@@ -1171,7 +1171,6 @@ namespace ts {
     }
 
     const invalidOperationsInPartialSemanticMode: readonly (keyof LanguageService)[] = [
-        "getSyntacticDiagnostics",
         "getSemanticDiagnostics",
         "getSuggestionDiagnostics",
         "getCompilerOptionsDiagnostics",

src/testRunner/unittests/tsserver/partialSemanticServer.ts

@@ -111,6 +111,46 @@ import { something } from "something";
             assert.isTrue(hasException);
         });
 
+        it("allows syntactic diagnostic commands", () => {
+            const file1: File = {
+                path: `${tscWatch.projectRoot}/a.ts`,
+                content: `if (a < (b + c) { }`
+            };
+            const configFile: File = {
+                path: `${tscWatch.projectRoot}/tsconfig.json`,
+                content: `{}`
+            };
+            const expectedErrorMessage = "')' expected.";
+
+            const host = createServerHost([file1, libFile, configFile]);
+            const session = createSession(host, {
+                serverMode: LanguageServiceMode.PartialSemantic,
+                useSingleInferredProject: true,
+                logger: createLoggerWithInMemoryLogs()
+            });
+
+            const service = session.getProjectService();
+            openFilesForSession([file1], session);
+            const request: protocol.SyntacticDiagnosticsSyncRequest = {
+                type: "request",
+                seq: 1,
+                command: protocol.CommandTypes.SyntacticDiagnosticsSync,
+                arguments: { file: file1.path }
+            };
+            const response = session.executeCommandSeq(request).response as protocol.SyntacticDiagnosticsSyncResponse["body"];
+            assert.isDefined(response);
+            assert.equal(response!.length, 1);
+            assert.equal((response![0] as protocol.Diagnostic).text, expectedErrorMessage);
+
+            const project = service.inferredProjects[0];
+            const diagnostics = project.getLanguageService().getSyntacticDiagnostics(file1.path);
+            assert.isTrue(diagnostics.length === 1);
+            assert.equal(diagnostics[0].messageText, expectedErrorMessage);
+
+            verifyGetErrRequest({ session, host, files: [file1], skip: [{ semantic: true, suggestion: true }] });
+            baselineTsserverLogs("partialSemanticServer", "syntactic diagnostics are returned with no error", session);
+        });
+
         it("should not include auto type reference directives", () => {
             const { host, session, file1 } = setup();
             const atTypes: File = {

tests/baselines/reference/tsserver/partialSemanticServer/syntactic-diagnostics-are-returned-with-no-error.js

@@ -0,0 +1,31 @@
+Provided types map file "/a/lib/typesMap.json" doesn't exist
+request:{"seq":0,"type":"request","command":"open","arguments":{"file":"/user/username/projects/myproject/a.ts"}}
+Plugins were requested but not running in environment that supports 'require'. Nothing will be loaded
+Starting updateGraphWorker: Project: /dev/null/inferredProject1*
+Finishing updateGraphWorker: Project: /dev/null/inferredProject1* Version: 1 structureChanged: true structureIsReused:: Not Elapsed:: *ms
+Project '/dev/null/inferredProject1*' (Inferred)
+	Files (2)
+	/a/lib/lib.d.ts
+	/user/username/projects/myproject/a.ts
+
+
+	a/lib/lib.d.ts
+	  Default library for target 'es5'
+	user/username/projects/myproject/a.ts
+	  Root file specified for compilation
+
+-----------------------------------------------
+Project '/dev/null/inferredProject1*' (Inferred)
+	Files (2)
+
+-----------------------------------------------
+Open files: 
+	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+		Projects: /dev/null/inferredProject1*
+response:{"responseRequired":false}
+request:{"type":"request","seq":1,"command":"syntacticDiagnosticsSync","arguments":{"file":"/user/username/projects/myproject/a.ts"}}
+response:{"response":[{"start":{"line":1,"offset":17},"end":{"line":1,"offset":18},"text":"')' expected.","code":1005,"category":"error"}],"responseRequired":true}
+request:{"command":"geterr","arguments":{"delay":0,"files":["/user/username/projects/myproject/a.ts"]},"seq":2,"type":"request"}
+response:{"responseRequired":false}
+Session does not support events: ignored event: {"seq":0,"type":"event","event":"syntaxDiag","body":{"file":"/user/username/projects/myproject/a.ts","diagnostics":[{"start":{"line":1,"offset":17},"end":{"line":1,"offset":18},"text":"')' expected.","code":1005,"category":"error"}]}}
+Session does not support events: ignored event: {"seq":0,"type":"event","event":"requestCompleted","body":{"request_seq":2}}