Merge pull request #15260 from Microsoft/Fix15200

Fix #15200: Query for semantic errors on .js files with '@ts-check' with no config file

src/compiler/program.ts

@@ -908,6 +908,13 @@ namespace ts {
 
         function getSemanticDiagnosticsForFileNoCache(sourceFile: SourceFile, cancellationToken: CancellationToken): Diagnostic[] {
             return runWithCancellationToken(() => {
+                // If skipLibCheck is enabled, skip reporting errors if file is a declaration file.
+                // If skipDefaultLibCheck is enabled, skip reporting errors if file contains a
+                // '/// <reference no-default-lib="true"/>' directive.
+                if (options.skipLibCheck && sourceFile.isDeclarationFile || options.skipDefaultLibCheck && sourceFile.hasNoDefaultLib) {
+                    return emptyArray;
+                }
+
                 const typeChecker = getDiagnosticsProducingTypeChecker();
 
                 Debug.assert(!!sourceFile.bindDiagnostics);

src/harness/unittests/tsserverProjectSystem.ts

@@ -3204,6 +3204,122 @@ namespace ts.projectSystem {
             const errorResult = <protocol.Diagnostic[]>session.executeCommand(dTsFileGetErrRequest).response;
             assert.isTrue(errorResult.length === 0);
         });
+
+        it("should not report bind errors for declaration files with skipLibCheck=true", () => {
+            const jsconfigFile = {
+                path: "/a/jsconfig.json",
+                content: "{}"
+            };
+            const jsFile = {
+                path: "/a/jsFile.js",
+                content: "let x = 1;"
+            };
+            const dTsFile1 = {
+                path: "/a/dTsFile1.d.ts",
+                content: `
+                declare var x: number;`
+            };
+            const dTsFile2 = {
+                path: "/a/dTsFile2.d.ts",
+                content: `
+                declare var x: string;`
+            };
+            const host = createServerHost([jsconfigFile, jsFile, dTsFile1, dTsFile2]);
+            const session = createSession(host);
+            openFilesForSession([jsFile], session);
+
+            const dTsFile1GetErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
+                CommandNames.SemanticDiagnosticsSync,
+                { file: dTsFile1.path }
+            );
+            const error1Result = <protocol.Diagnostic[]>session.executeCommand(dTsFile1GetErrRequest).response;
+            assert.isTrue(error1Result.length === 0);
+
+             const dTsFile2GetErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
+                CommandNames.SemanticDiagnosticsSync,
+                { file: dTsFile2.path }
+            );
+            const error2Result = <protocol.Diagnostic[]>session.executeCommand(dTsFile2GetErrRequest).response;
+            assert.isTrue(error2Result.length === 0);
+        });
+
+        it("should report semanitc errors for loose JS files with '// @ts-check' and skipLibCheck=true", () => {
+            const jsFile = {
+                path: "/a/jsFile.js",
+                content: `
+                // @ts-check
+                let x = 1;
+                x === "string";`
+            };
+
+            const host = createServerHost([jsFile]);
+            const session = createSession(host);
+            openFilesForSession([jsFile], session);
+
+            const getErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
+                CommandNames.SemanticDiagnosticsSync,
+                { file: jsFile.path }
+            );
+            const errorResult = <protocol.Diagnostic[]>session.executeCommand(getErrRequest).response;
+            assert.isTrue(errorResult.length === 1);
+            assert.equal(errorResult[0].code, Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2.code);
+        });
+
+        it("should report semanitc errors for configured js project with '// @ts-check' and skipLibCheck=true", () => {
+            const jsconfigFile = {
+                path: "/a/jsconfig.json",
+                content: "{}"
+            };
+
+            const jsFile = {
+                path: "/a/jsFile.js",
+                content: `
+                // @ts-check
+                let x = 1;
+                x === "string";`
+            };
+
+            const host = createServerHost([jsconfigFile, jsFile]);
+            const session = createSession(host);
+            openFilesForSession([jsFile], session);
+
+            const getErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
+                CommandNames.SemanticDiagnosticsSync,
+                { file: jsFile.path }
+            );
+            const errorResult = <protocol.Diagnostic[]>session.executeCommand(getErrRequest).response;
+            assert.isTrue(errorResult.length === 1);
+            assert.equal(errorResult[0].code, Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2.code);
+        });
+
+        it("should report semanitc errors for configured js project with checkJs=true and skipLibCheck=true", () => {
+            const jsconfigFile = {
+                path: "/a/jsconfig.json",
+                content: JSON.stringify({
+                    compilerOptions: {
+                        checkJs: true,
+                        skipLibCheck: true
+                    },
+                })
+            };
+            const jsFile = {
+                path: "/a/jsFile.js",
+                content: `let x = 1;
+                x === "string";`
+            };
+
+            const host = createServerHost([jsconfigFile, jsFile]);
+            const session = createSession(host);
+            openFilesForSession([jsFile], session);
+
+            const getErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
+                CommandNames.SemanticDiagnosticsSync,
+                { file: jsFile.path }
+            );
+            const errorResult = <protocol.Diagnostic[]>session.executeCommand(getErrRequest).response;
+            assert.isTrue(errorResult.length === 1);
+            assert.equal(errorResult[0].code, Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2.code);
+        });
     });
 
     describe("non-existing directories listed in config file input array", () => {

src/server/session.ts

@@ -25,15 +25,26 @@ namespace ts.server {
         return ((1e9 * seconds) + nanoseconds) / 1000000.0;
     }
 
-    function shouldSkipSemanticCheck(project: Project) {
-        if (project.projectKind === ProjectKind.Inferred || project.projectKind === ProjectKind.External) {
-            return project.isJsOnlyProject();
-        }
-        else {
-            // For configured projects, require that skipLibCheck be set also
-            const options = project.getCompilerOptions();
-            return options.skipLibCheck && !options.checkJs && project.isJsOnlyProject();
+    function isDeclarationFileInJSOnlyNonConfiguredProject(project: Project, file: NormalizedPath) {
+        // Checking for semantic diagnostics is an expensive process. We want to avoid it if we
+        // know for sure it is not needed.
+        // For instance, .d.ts files injected by ATA automatically do not produce any relevant
+        // errors to a JS- only project.
+        //
+        // Note that configured projects can set skipLibCheck (on by default in jsconfig.json) to
+        // disable checking for declaration files. We only need to verify for inferred projects (e.g.
+        // miscellaneous context in VS) and external projects(e.g.VS.csproj project) with only JS
+        // files.
+        //
+        // We still want to check .js files in a JS-only inferred or external project (e.g. if the
+        // file has '// @ts-check').
+
+        if ((project.projectKind === ProjectKind.Inferred || project.projectKind === ProjectKind.External) &&
+            project.isJsOnlyProject()) {
+            const scriptInfo = project.getScriptInfoForNormalizedPath(file);
+            return scriptInfo && !scriptInfo.isJavaScript();
         }
+        return false;
     }
 
     interface FileStart {
@@ -489,7 +500,7 @@ namespace ts.server {
         private semanticCheck(file: NormalizedPath, project: Project) {
             try {
                 let diags: Diagnostic[] = [];
-                if (!shouldSkipSemanticCheck(project)) {
+                if (!isDeclarationFileInJSOnlyNonConfiguredProject(project, file)) {
                     diags = project.getLanguageService().getSemanticDiagnostics(file);
                 }
 
@@ -597,7 +608,7 @@ namespace ts.server {
 
         private getDiagnosticsWorker(args: protocol.FileRequestArgs, isSemantic: boolean, selector: (project: Project, file: string) => Diagnostic[], includeLinePosition: boolean) {
             const { project, file } = this.getFileAndProject(args);
-            if (isSemantic && shouldSkipSemanticCheck(project)) {
+            if (isSemantic && isDeclarationFileInJSOnlyNonConfiguredProject(project, file)) {
                 return [];
             }
             const scriptInfo = project.getScriptInfoForNormalizedPath(file);

tests/cases/compiler/noDefaultLib.ts

@@ -1,3 +1,4 @@
+// @skipDefaultLibCheck: false
 /// <reference no-default-lib="true"/>
 var x;
 

tests/cases/compiler/variableDeclarationInStrictMode1.ts

@@ -1,2 +1,3 @@
+// @skipDefaultLibCheck: false
 "use strict";
 var eval;