allow backslashes in fileName argument of the transpile function

Author: vladima

src/services/services.ts

@@ -1866,7 +1866,7 @@ namespace ts {
         let sourceMapText: string;
         // Create a compilerHost object to allow the compiler to read and write files
         let compilerHost: CompilerHost = {
-            getSourceFile: (fileName, target) => fileName === inputFileName ? sourceFile : undefined,
+            getSourceFile: (fileName, target) => fileName === normalizeSlashes(inputFileName) ? sourceFile : undefined,
             writeFile: (name, text, writeByteOrderMark) => {
                 if (fileExtensionIs(name, ".map")) {
                     Debug.assert(sourceMapText === undefined, `Unexpected multiple source map outputs for the file '${name}'`);

tests/cases/unittests/transpile.ts

@@ -64,8 +64,8 @@ module ts {
             let transpileModuleResultWithSourceMap = transpileModule(input, transpileOptions);
             assert.isTrue(transpileModuleResultWithSourceMap.sourceMapText !== undefined);
 
-            let expectedSourceMapFileName = removeFileExtension(transpileOptions.fileName) + ".js.map";
-            let expectedSourceMappingUrlLine = `//# sourceMappingURL=${expectedSourceMapFileName}`;           
+            let expectedSourceMapFileName = removeFileExtension(getBaseFileName(normalizeSlashes(transpileOptions.fileName))) + ".js.map";
+            let expectedSourceMappingUrlLine = `//# sourceMappingURL=${expectedSourceMapFileName}`;
 
             if (testSettings.expectedOutput !== undefined) {
                 assert.equal(transpileModuleResultWithSourceMap.outputText, testSettings.expectedOutput + expectedSourceMappingUrlLine);    
@@ -270,5 +270,9 @@ var x = 0;`,
                     expectedOutput: output
                 });
         });
+
+        it("Supports backslashes in file name", () => {
+            test("var x", { expectedOutput: "var x;\r\n", options: { fileName: "a\\b.ts" }});
+        });
     });
 }