Add listFilesOnly command-line option

Msbuild currently uses a combination of `--listFiles` and `--noEmit` to
obtain a list of files to be consumed by tsc.  However, these two flags
don't suppress type checking, the results of which msbuild will never
consume.  This new switch gives msbuild a faster way to obtain the file
list.

Note: like `--noEmit`, doesn't make sense in build mode.

src/compiler/checker.ts

@@ -29651,7 +29651,7 @@ namespace ts {
 
         function checkCollisionWithArgumentsInGeneratedCode(node: SignatureDeclaration) {
             // no rest parameters \ declaration context \ overload - no codegen impact
-            if (languageVersion >= ScriptTarget.ES2015 || compilerOptions.noEmit || !hasRestParameter(node) || node.flags & NodeFlags.Ambient || nodeIsMissing((<FunctionLikeDeclaration>node).body)) {
+            if (languageVersion >= ScriptTarget.ES2015 || shouldSuppressEmit(compilerOptions) || !hasRestParameter(node) || node.flags & NodeFlags.Ambient || nodeIsMissing((<FunctionLikeDeclaration>node).body)) {
                 return;
             }
 
@@ -29726,7 +29726,7 @@ namespace ts {
 
         function checkCollisionWithRequireExportsInGeneratedCode(node: Node, name: Identifier) {
             // No need to check for require or exports for ES6 modules and later
-            if (moduleKind >= ModuleKind.ES2015 || compilerOptions.noEmit) {
+            if (moduleKind >= ModuleKind.ES2015 || shouldSuppressEmit(compilerOptions)) {
                 return;
             }
 
@@ -29749,7 +29749,7 @@ namespace ts {
         }
 
         function checkCollisionWithGlobalPromiseInGeneratedCode(node: Node, name: Identifier): void {
-            if (languageVersion >= ScriptTarget.ES2017 || compilerOptions.noEmit || !needCollisionCheckForIdentifier(node, name, "Promise")) {
+            if (languageVersion >= ScriptTarget.ES2017 || shouldSuppressEmit(compilerOptions) || !needCollisionCheckForIdentifier(node, name, "Promise")) {
                 return;
             }
 
@@ -35639,7 +35639,7 @@ namespace ts {
                 return grammarErrorOnNode(node.exclamationToken, Diagnostics.Definite_assignment_assertions_can_only_be_used_along_with_a_type_annotation);
             }
 
-            if (compilerOptions.module !== ModuleKind.ES2015 && compilerOptions.module !== ModuleKind.ESNext && compilerOptions.module !== ModuleKind.System && !compilerOptions.noEmit &&
+            if (compilerOptions.module !== ModuleKind.ES2015 && compilerOptions.module !== ModuleKind.ESNext && compilerOptions.module !== ModuleKind.System && !shouldSuppressEmit(compilerOptions) &&
                 !(node.parent.parent.flags & NodeFlags.Ambient) && hasModifier(node.parent.parent, ModifierFlags.Export)) {
                 checkESModuleMarker(node.name);
             }

src/compiler/commandLineParser.ts

@@ -216,6 +216,13 @@ namespace ts {
             isCommandLineOnly: true,
             description: Diagnostics.Print_the_final_configuration_instead_of_building
         },
+        {
+            name: "listFilesOnly",
+            type: "boolean",
+            category: Diagnostics.Command_line_Options,
+            isCommandLineOnly: true,
+            description: Diagnostics.Print_names_of_files_that_are_part_of_the_compilation_and_then_stop_processing
+        },
 
         // Basic
         {

src/compiler/diagnosticMessages.json

@@ -4311,6 +4311,10 @@
         "category": "Message",
         "code": 6502
     },
+    "Print names of files that are part of the compilation and then stop processing.": {
+        "category": "Message",
+        "code": 6503
+    },
 
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",

src/compiler/emitter.ts

@@ -332,7 +332,7 @@ namespace ts {
             // Write build information if applicable
             if (!buildInfoPath || targetSourceFile || emitSkipped) return;
             const program = host.getProgramBuildInfo();
-            if (host.isEmitBlocked(buildInfoPath) || compilerOptions.noEmit) {
+            if (host.isEmitBlocked(buildInfoPath) || shouldSuppressEmit(compilerOptions)) {
                 emitSkipped = true;
                 return;
             }
@@ -349,7 +349,7 @@ namespace ts {
             }
 
             // Make sure not to write js file and source map file if any of them cannot be written
-            if ((jsFilePath && host.isEmitBlocked(jsFilePath)) || compilerOptions.noEmit) {
+            if ((jsFilePath && host.isEmitBlocked(jsFilePath)) || shouldSuppressEmit(compilerOptions)) {
                 emitSkipped = true;
                 return;
             }
@@ -436,7 +436,7 @@ namespace ts {
                 onEmitNode: declarationTransform.emitNodeWithNotification,
                 substituteNode: declarationTransform.substituteNode,
             });
-            const declBlocked = (!!declarationTransform.diagnostics && !!declarationTransform.diagnostics.length) || !!host.isEmitBlocked(declarationFilePath) || !!compilerOptions.noEmit;
+            const declBlocked = (!!declarationTransform.diagnostics && !!declarationTransform.diagnostics.length) || !!host.isEmitBlocked(declarationFilePath) || !!shouldSuppressEmit(compilerOptions);
             emitSkipped = emitSkipped || declBlocked;
             if (!declBlocked || forceDtsEmit) {
                 Debug.assert(declarationTransform.transformed.length === 1, "Should only see one output from the decl transform");

src/compiler/program.ts

@@ -1560,6 +1560,7 @@ namespace ts {
         }
 
         function getDiagnosticsProducingTypeChecker() {
+            Debug.assert(!options.listFilesOnly || !!options.extendedDiagnostics);
             return diagnosticsProducingTypeChecker || (diagnosticsProducingTypeChecker = createTypeChecker(program, /*produceDiagnostics:*/ true));
         }
 
@@ -1582,11 +1583,11 @@ namespace ts {
         function emitWorker(program: Program, sourceFile: SourceFile | undefined, writeFileCallback: WriteFileCallback | undefined, cancellationToken: CancellationToken | undefined, emitOnlyDtsFiles?: boolean, customTransformers?: CustomTransformers, forceDtsEmit?: boolean): EmitResult {
             let declarationDiagnostics: readonly Diagnostic[] = [];
 
-            if (!forceDtsEmit) {
-                if (options.noEmit) {
-                    return { diagnostics: declarationDiagnostics, sourceMaps: undefined, emittedFiles: undefined, emitSkipped: true };
-                }
+            if (options.listFilesOnly || (!forceDtsEmit && shouldSuppressEmit(options))) {
+                return { diagnostics: declarationDiagnostics, sourceMaps: undefined, emittedFiles: undefined, emitSkipped: true };
+            }
 
+            if (!forceDtsEmit) {
                 // If the noEmitOnError flag is set, then check if we have any errors so far.  If so,
                 // immediately bail out.  Note that we pass 'undefined' for 'sourceFile' so that we
                 // get any preEmit diagnostics, not just the ones
@@ -2036,7 +2037,9 @@ namespace ts {
         }
 
         function getGlobalDiagnostics(): SortedReadonlyArray<Diagnostic> {
-            return rootNames.length ? sortAndDeduplicateDiagnostics(getDiagnosticsProducingTypeChecker().getGlobalDiagnostics().slice()) : emptyArray as any as SortedReadonlyArray<Diagnostic>;
+            return !options.listFilesOnly && rootNames.length
+                ? sortAndDeduplicateDiagnostics(getDiagnosticsProducingTypeChecker().getGlobalDiagnostics().slice())
+                : emptyArray as any as SortedReadonlyArray<Diagnostic>;
         }
 
         function getConfigFileParsingDiagnostics(): readonly Diagnostic[] {
@@ -3089,7 +3092,7 @@ namespace ts {
                     createDiagnosticForOptionName(Diagnostics.Option_0_cannot_be_specified_without_specifying_option_1_or_option_2, "emitDeclarationOnly", "declaration", "composite");
                 }
 
-                if (options.noEmit) {
+                if (shouldSuppressEmit(options)) {
                     createDiagnosticForOptionName(Diagnostics.Option_0_cannot_be_specified_with_option_1, "emitDeclarationOnly", "noEmit");
                 }
             }
@@ -3112,7 +3115,7 @@ namespace ts {
             }
 
             // If the emit is enabled make sure that every output file is unique and not overwriting any of the input files
-            if (!options.noEmit && !options.suppressOutputPathCheck) {
+            if (!shouldSuppressEmit(options) && !options.suppressOutputPathCheck) {
                 const emitHost = getEmitHost();
                 const emitFilesSeen = createMap<true>();
                 forEachEmittedFile(emitHost, (emitFileNames) => {
@@ -3181,7 +3184,7 @@ namespace ts {
         }
 
         function verifyProjectReferences() {
-            const buildInfoPath = !options.noEmit && !options.suppressOutputPathCheck ? getTsBuildInfoEmitOutputFilePath(options) : undefined;
+            const buildInfoPath = !shouldSuppressEmit(options) && !options.suppressOutputPathCheck ? getTsBuildInfoEmitOutputFilePath(options) : undefined;
             forEachProjectReference(projectReferences, resolvedProjectReferences, (resolvedRef, index, parent) => {
                 const ref = (parent ? parent.commandLine.projectReferences : projectReferences)![index];
                 const parentFile = parent && parent.sourceFile as JsonSourceFile;
@@ -3322,7 +3325,7 @@ namespace ts {
         }
 
         function isEmittedFile(file: string): boolean {
-            if (options.noEmit) {
+            if (shouldSuppressEmit(options)) {
                 return false;
             }
 

src/compiler/tsbuild.ts

@@ -167,6 +167,7 @@ namespace ts {
         /*@internal*/ preserveWatchOutput?: boolean;
         /*@internal*/ listEmittedFiles?: boolean;
         /*@internal*/ listFiles?: boolean;
+        /*@internal*/ listFilesOnly?: boolean;
         /*@internal*/ pretty?: boolean;
         incremental?: boolean;
 
@@ -1923,7 +1924,7 @@ namespace ts {
     }
 
     function isOutputFile(state: SolutionBuilderState, fileName: string, configFile: ParsedCommandLine) {
-        if (configFile.options.noEmit) return false;
+        if (shouldSuppressEmit(configFile.options)) return false;
 
         // ts or tsx files are not output
         if (!fileExtensionIs(fileName, Extension.Dts) &&

src/compiler/types.ts

@@ -4951,6 +4951,7 @@ namespace ts {
         lib?: string[];
         /*@internal*/listEmittedFiles?: boolean;
         /*@internal*/listFiles?: boolean;
+        /*@internal*/listFilesOnly?: boolean;
         locale?: string;
         mapRoot?: string;
         maxNodeModuleJsDepth?: number;

src/compiler/utilities.ts

@@ -7619,6 +7619,14 @@ namespace ts {
         return option.strictFlag ? getStrictOptionValue(options, option.name as StrictOptionName) : options[option.name];
     }
 
+    export function shouldSuppressEmit(options: CompilerOptions): boolean {
+        return !!options.noEmit || !!options.listFilesOnly;
+    }
+
+    export function shouldListFiles(options: CompilerOptions): boolean {
+        return !!options.listFiles || !!options.listFilesOnly;
+    }
+
     export function hasZeroOrOneAsteriskCharacter(str: string): boolean {
         let seenAsterisk = false;
         for (let i = 0; i < str.length; i++) {
@@ -8339,7 +8347,8 @@ namespace ts {
         // 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.
-        return (options.skipLibCheck && sourceFile.isDeclarationFile ||
+        return options.listFilesOnly ||
+            (options.skipLibCheck && sourceFile.isDeclarationFile ||
             options.skipDefaultLibCheck && sourceFile.hasNoDefaultLib) ||
             host.isSourceOfProjectReferenceRedirect(sourceFile.fileName);
     }

src/compiler/watch.ts

@@ -129,7 +129,7 @@ namespace ts {
     }
 
     export function listFiles(program: ProgramToEmitFilesAndReportErrors, writeFileName: (s: string) => void) {
-        if (program.getCompilerOptions().listFiles) {
+        if (shouldListFiles(program.getCompilerOptions())) {
             forEach(program.getSourceFiles(), file => {
                 writeFileName(file.fileName);
             });

src/testRunner/unittests/config/commandLineParsing.ts

@@ -446,6 +446,23 @@ namespace ts {
                 });
         });
 
+        it("parse build with listFilesOnly ", () => {
+            // --lib es6 0.ts
+            assertParseResult(["--listFilesOnly"],
+                {
+                    errors: [{
+                        messageText:"Unknown build option '--listFilesOnly'.",
+                        category: Diagnostics.Unknown_build_option_0.category,
+                        code: Diagnostics.Unknown_build_option_0.code,
+                        file: undefined,
+                        start: undefined,
+                        length: undefined,
+                    }],
+                    projects: ["."],
+                    buildOptions: {}
+                });
+        });
+
         it("Parse multiple flags with input projects at the end", () => {
             // --lib es5,es2015.symbol.wellknown --target es5 0.ts
             assertParseResult(["--force", "--verbose", "src", "tests"],

src/tsc/executeCommandLine.ts

@@ -207,6 +207,11 @@ namespace ts {
             return sys.exit(ExitStatus.Success);
         }
 
+        if (commandLine.options.watch && commandLine.options.listFilesOnly) {
+            reportDiagnostic(createCompilerDiagnostic(Diagnostics.Options_0_and_1_cannot_be_combined, "watch", "listFilesOnly"));
+            return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
+        }
+
         if (commandLine.options.project) {
             if (commandLine.fileNames.length !== 0) {
                 reportDiagnostic(createCompilerDiagnostic(Diagnostics.Option_project_cannot_be_mixed_with_source_files_on_a_command_line));

tests/baselines/reference/showConfig/Shows tsconfig for single option/listFilesOnly/tsconfig.json

@@ -0,0 +1,5 @@
+{
+    "compilerOptions": {
+        "listFilesOnly": true
+    }
+}

tests/cases/fourslash/listFilesOnly.ts

@@ -0,0 +1,10 @@
+/// <reference path='fourslash.ts' />
+
+// @listFilesOnly: true
+
+// @Filename: a.js
+////const x = 1;
+
+// Just want to see that no baseline is emitted
+
+verify.noErrors();