Fix out of bounds panic when tsconfig "files" contains duplicates

internal/tsoptions/parsedcommandline.go

@@ -37,6 +37,7 @@ type ParsedCommandLine struct {
 	resolvedProjectReferencePaths     []string
 	resolvedProjectReferencePathsOnce sync.Once
 
+	literalFileNamesLen int
 	fileNamesByPath     map[tspath.Path]string // maps file names to their paths, used for quick lookups
 	fileNamesByPathOnce sync.Once
 }
@@ -217,7 +218,7 @@ func (p *ParsedCommandLine) WildcardDirectories() map[string]bool {
 // Normalized file names explicitly specified in `files`
 func (p *ParsedCommandLine) LiteralFileNames() []string {
 	if p != nil && p.ConfigFile != nil {
-		return p.FileNames()[0:len(p.ConfigFile.configFileSpecs.validatedFilesSpec)]
+		return p.FileNames()[0:p.literalFileNamesLen]
 	}
 	return nil
 }
@@ -349,13 +350,14 @@ func (p *ParsedCommandLine) GetMatchedIncludeSpec(fileName string) (string, bool
 
 func (p *ParsedCommandLine) ReloadFileNamesOfParsedCommandLine(fs vfs.FS) *ParsedCommandLine {
 	parsedConfig := *p.ParsedConfig
-	parsedConfig.FileNames = getFileNamesFromConfigSpecs(
+	fileNames, literalFileNamesLen := getFileNamesFromConfigSpecs(
 		*p.ConfigFile.configFileSpecs,
 		p.GetCurrentDirectory(),
 		p.CompilerOptions(),
 		fs,
 		p.extraFileExtensions,
 	)
+	parsedConfig.FileNames = fileNames
 	parsedCommandLine := ParsedCommandLine{
 		ParsedConfig:        &parsedConfig,
 		ConfigFile:          p.ConfigFile,
@@ -365,6 +367,7 @@ func (p *ParsedCommandLine) ReloadFileNamesOfParsedCommandLine(fs vfs.FS) *Parse
 		comparePathsOptions: p.comparePathsOptions,
 		wildcardDirectories: p.wildcardDirectories,
 		extraFileExtensions: p.extraFileExtensions,
+		literalFileNamesLen: literalFileNamesLen,
 	}
 	return &parsedCommandLine
 }

internal/tsoptions/parsedcommandline_test.go

@@ -111,6 +111,28 @@ func TestParsedCommandLine(t *testing.T) {
 					"/dev/b.ts",
 				})
 			})
+
+			t.Run("duplicates", func(t *testing.T) {
+				t.Parallel()
+				parsedCommandLine := tsoptionstest.GetParsedCommandLine(
+					t,
+					`{
+						"files": [
+							"a.ts",
+							"a.ts",
+							"b.ts",
+						]
+					}`,
+					files,
+					"/dev",
+					/*useCaseSensitiveFileNames*/ true,
+				)
+
+				assert.DeepEqual(t, parsedCommandLine.LiteralFileNames(), []string{
+					"/dev/a.ts",
+					"/dev/b.ts",
+				})
+			})
 		})
 
 		t.Run("with literal include list", func(t *testing.T) {

internal/tsoptions/tsconfigparsing.go

@@ -1269,9 +1269,9 @@ func parseJsonConfigFileContentWorker(
 		sourceFile.configFileSpecs = &configFileSpecs
 	}
 
-	getFileNames := func(basePath string) []string {
+	getFileNames := func(basePath string) ([]string, int) {
 		parsedConfigOptions := parsedConfig.options
-		fileNames := getFileNamesFromConfigSpecs(configFileSpecs, basePath, parsedConfigOptions, host.FS(), extraFileExtensions)
+		fileNames, literalFileNamesLen := getFileNamesFromConfigSpecs(configFileSpecs, basePath, parsedConfigOptions, host.FS(), extraFileExtensions)
 		if shouldReportNoInputFiles(fileNames, canJsonReportNoInputFiles(rawConfig), resolutionStack) {
 			includeSpecs := configFileSpecs.includeSpecs
 			excludeSpecs := configFileSpecs.excludeSpecs
@@ -1283,7 +1283,7 @@ func parseJsonConfigFileContentWorker(
 			}
 			errors = append(errors, ast.NewCompilerDiagnostic(diagnostics.No_inputs_were_found_in_config_file_0_Specified_include_paths_were_1_and_exclude_paths_were_2, configFileName, core.Must(core.StringifyJson(includeSpecs, "", "")), core.Must(core.StringifyJson(excludeSpecs, "", ""))))
 		}
-		return fileNames
+		return fileNames, literalFileNamesLen
 	}
 
 	getProjectReferences := func(basePath string) []*core.ProjectReference {
@@ -1310,12 +1310,13 @@ func parseJsonConfigFileContentWorker(
 		return projectReferences
 	}
 
+	fileNames, literalFileNamesLen := getFileNames(basePathForFileNames)
 	return &ParsedCommandLine{
 		ParsedConfig: &core.ParsedOptions{
 			CompilerOptions: parsedConfig.options,
 			TypeAcquisition: parsedConfig.typeAcquisition,
 			// WatchOptions:      nil,
-			FileNames:         getFileNames(basePathForFileNames),
+			FileNames:         fileNames,
 			ProjectReferences: getProjectReferences(basePathForFileNames),
 		},
 		ConfigFile: sourceFile,
@@ -1327,6 +1328,7 @@ func parseJsonConfigFileContentWorker(
 			UseCaseSensitiveFileNames: host.FS().UseCaseSensitiveFileNames(),
 			CurrentDirectory:          basePathForFileNames,
 		},
+		literalFileNamesLen: literalFileNamesLen,
 	}
 }
 
@@ -1608,7 +1610,7 @@ func getFileNamesFromConfigSpecs(
 	options *core.CompilerOptions,
 	host vfs.FS,
 	extraFileExtensions []FileExtensionInfo,
-) []string {
+) ([]string, int) {
 	extraFileExtensions = []FileExtensionInfo{}
 	basePath = tspath.NormalizePath(basePath)
 	keyMappper := func(value string) string { return tspath.GetCanonicalFileName(value, host.UseCaseSensitiveFileNames()) }
@@ -1696,7 +1698,7 @@ func getFileNamesFromConfigSpecs(
 	for file := range wildCardJsonFileMap.Values() {
 		files = append(files, file)
 	}
-	return files
+	return files, literalFileMap.Size()
 }
 
 func GetSupportedExtensions(compilerOptions *core.CompilerOptions, extraFileExtensions []FileExtensionInfo) [][]string {