Fix self reference package with casing

Author: sheetalkamat

src/compiler/moduleNameResolver.ts

@@ -2249,7 +2249,7 @@ namespace ts {
                 if ((extensions === Extensions.TypeScript || extensions === Extensions.JavaScript || extensions === Extensions.Json)
                     && (state.compilerOptions.declarationDir || state.compilerOptions.outDir)
                     && finalPath.indexOf("/node_modules/") === -1
-                    && (state.compilerOptions.configFile ? startsWith(toAbsolutePath(state.compilerOptions.configFile.fileName), scope.packageDirectory) : true)
+                    && (state.compilerOptions.configFile ? containsPath(scope.packageDirectory, toAbsolutePath(state.compilerOptions.configFile.fileName), !useCaseSensitiveFileNames()) : true)
                 ) {
                     // So that all means we'll only try these guesses for files outside `node_modules` in a directory where the `package.json` and `tsconfig.json` are siblings.
                     // Even with all that, we still don't know if the root of the output file structure will be (relative to the package file)
@@ -2310,7 +2310,7 @@ namespace ts {
                     for (const commonSourceDirGuess of commonSourceDirGuesses) {
                         const candidateDirectories = getOutputDirectoriesForBaseDirectory(commonSourceDirGuess);
                         for (const candidateDir of candidateDirectories) {
-                            if (startsWith(finalPath, candidateDir)) {
+                            if (containsPath(candidateDir, finalPath, !useCaseSensitiveFileNames())) {
                                 // The matched export is looking up something in either the out declaration or js dir, now map the written path back into the source dir and source extension
                                 const pathFragment = finalPath.slice(candidateDir.length + 1); // +1 to also remove directory seperator
                                 const possibleInputBase = combinePaths(commonSourceDirGuess, pathFragment);

tests/baselines/reference/tscWatch/forceConsistentCasingInFileNames/self-name-package-reference.js

@@ -35,28 +35,19 @@ Found 'package.json' at '/users/name/projects/web/package.json'.
 ======== Resolving module '@this/package' from '/Users/name/projects/web/index.ts'. ========
 Module resolution kind is not specified, using 'NodeNext'.
 File '/users/name/projects/web/package.json' exists according to earlier cached lookups.
-File '/users/name/projects/web/index.ts' exist - use it as a name resolution result.
-Resolving real path for '/users/name/projects/web/index.ts', result '/Users/name/projects/web/index.ts'.
-======== Module name '@this/package' was successfully resolved to '/users/name/projects/web/index.ts'. ========
+File '/Users/name/projects/web/index.ts' exist - use it as a name resolution result.
+Resolving real path for '/Users/name/projects/web/index.ts', result '/Users/name/projects/web/index.ts'.
+======== Module name '@this/package' was successfully resolved to '/Users/name/projects/web/index.ts'. ========
 File '/a/lib/package.json' does not exist.
 File '/a/package.json' does not exist.
 File '/package.json' does not exist.
-index.ts:1:21 - error TS1149: File name '/users/name/projects/web/index.ts' differs from already included file name '/Users/name/projects/web/index.ts' only in casing.
-  The file is in the program because:
-    Matched by default include pattern '**/*'
-    Imported via "@this/package" from file '/Users/name/projects/web/index.ts'
-  File is ECMAScript module because '/users/name/projects/web/package.json' has field "type" with value "module"
-
-1 import * as me from "@this/package";
-                      ~~~~~~~~~~~~~~~
-
 ../../../../a/lib/lib.esnext.full.d.ts
   Default library for target 'esnext'
 index.ts
   Matched by default include pattern '**/*'
   Imported via "@this/package" from file 'index.ts'
   File is ECMAScript module because 'package.json' has field "type" with value "module"
-[[90m12:00:36 AM[0m] Found 1 error. Watching for file changes.
+[[90m12:00:36 AM[0m] Found 0 errors. Watching for file changes.