Remove getDefaultLibFilename from the LS host interface as its result is never honored by the LS.

The LS operate only on a fixed list of files initialized by the host's getScriptFileNames(), if a file is not in this list, it will not be queried from the host, rather considered a missing file. Thus the result of getDefaultLibFilename()is either in the list, or will be ignored.

src/harness/harnessLanguageService.ts

@@ -217,10 +217,6 @@ module Harness.LanguageService {
             return "";
         }
 
-        public getDefaultLibFilename(): string {
-            return "";
-        }
-
         public getScriptFileNames(): string {
             var fileNames: string[] = [];
             ts.forEachKey(this.fileNameToScript, (fileName) => { fileNames.push(fileName); });

src/services/services.ts

@@ -853,7 +853,6 @@ module ts {
         getLocalizedDiagnosticMessages?(): any;
         getCancellationToken?(): CancellationToken;
         getCurrentDirectory(): string;
-        getDefaultLibFilename(options: CompilerOptions): string;
         log? (s: string): void;
         trace? (s: string): void;
         error? (s: string): void;
@@ -1964,21 +1963,14 @@ module ts {
 
         function createCompilerHost(): CompilerHost {
             return {
-                getSourceFile: (filename, languageVersion) => {
-                    return getSourceFile(filename);
-                },
+                getSourceFile: getSourceFile,
                 getCancellationToken: () => cancellationToken,
-                getCanonicalFileName: (filename) => useCaseSensitivefilenames ? filename : filename.toLowerCase(),
+                getCanonicalFileName: filename => useCaseSensitivefilenames ? filename : filename.toLowerCase(),
                 useCaseSensitiveFileNames: () => useCaseSensitivefilenames,
                 getNewLine: () => "\r\n",
-                getDefaultLibFilename: (options): string => {
-                    return host.getDefaultLibFilename(options);
-                },
-                writeFile: (filename, data, writeByteOrderMark) => {
-                },
-                getCurrentDirectory: (): string => {
-                    return host.getCurrentDirectory();
-                }
+                getDefaultLibFilename: getDefaultLibraryFilename,
+                writeFile: (filename, data, writeByteOrderMark) => { },
+                getCurrentDirectory: () => host.getCurrentDirectory()
             };
         }
 

src/services/shims.ts

@@ -55,7 +55,6 @@ module ts {
         getLocalizedDiagnosticMessages(): string;
         getCancellationToken(): CancellationToken;
         getCurrentDirectory(): string;
-        getDefaultLibFilename(options: string): string;
     }
 
     ///
@@ -275,10 +274,6 @@ module ts {
             return this.shimHost.getCancellationToken();
         }
 
-        public getDefaultLibFilename(options: CompilerOptions): string {
-            return this.shimHost.getDefaultLibFilename(JSON.stringify(options));
-        }
-
         public getCurrentDirectory(): string {
             return this.shimHost.getCurrentDirectory();
         }