Merge pull request microsoft#12667 from bb/patch-1

Normalize 'basePath' in 'parseJsonConfigFileContent'

Author: mhegazy

src/compiler/commandLineParser.ts

@@ -842,6 +842,7 @@ namespace ts {
       */
     export function parseJsonConfigFileContent(json: any, host: ParseConfigHost, basePath: string, existingOptions: CompilerOptions = {}, configFileName?: string, resolutionStack: Path[] = [], extraFileExtensions: FileExtensionInfo[] = []): ParsedCommandLine {
         const errors: Diagnostic[] = [];
+        basePath = normalizeSlashes(basePath);
         const getCanonicalFileName = createGetCanonicalFileName(host.useCaseSensitiveFileNames);
         const resolvedPath = toPath(configFileName || "", basePath, getCanonicalFileName);
         if (resolutionStack.indexOf(resolvedPath) >= 0) {