WIP

src/compiler/checker.ts

@@ -1430,6 +1430,7 @@ namespace ts {
                         error(errorNode, diag, tsExtension, removeExtension(moduleName, tsExtension));
                     }
                     else {
+                        debugger;
                         error(errorNode, moduleNotFoundError, moduleName);
                     }
                 }

src/compiler/moduleNameResolver.ts

@@ -571,7 +571,7 @@ namespace ts {
     }
 
     function resolvedWithRealpath(resolved: Resolved, host: ModuleResolutionHost, traceEnabled: boolean): Resolved {
-        if (!host.realpath || resolved.extension !== Extension.Dts) {//(!false) {//(!host.realpath) { //TODO: Kill this fn
+        if (!false) {//if (!host.realpath || resolved.extension !== Extension.Dts) {//(!false) {//(!host.realpath) { //TODO: Kill this fn
             return resolved;
         }
 

src/compiler/program.ts

@@ -359,7 +359,10 @@ namespace ts {
         }
 
         //Keys must be real paths!!!
+        //above not quite true any more
         const filesByName = createFileMap<SourceFile>();
+        const symlinkedFiles = createFileMap<SourceFile>();
+
         // stores 'filename -> file association' ignoring case
         // used to track cases when two file names differ only in casing
         const filesByNameIgnoreCase = host.useCaseSensitiveFileNames() ? createFileMap<SourceFile>(fileName => fileName.toLowerCase()) : undefined;
@@ -578,6 +581,7 @@ namespace ts {
             for (let i = 0, len = newSourceFiles.length; i < len; i++) {
                 filesByName.set(filePaths[i], newSourceFiles[i]);
             }
+            //update symlinkedFiles too?
 
             files = newSourceFiles;
             fileProcessingDiagnostics = oldProgram.getFileProcessingDiagnostics();
@@ -686,13 +690,13 @@ namespace ts {
         }
 
         function getSourceFileByPath(path: Path): SourceFile { //path is logical
-            return filesByName.get(path); //realpath(path));
+            return filesByName.get(path) || symlinkedFiles.get(path); //realpath(path));
         }
 
         //neater
-        //function realpath(path: Path): Path {
-        //    return host.realpath ? (host.realpath(path) as Path) : path;
-        //}
+        function realpath(path: Path): Path {
+            return host.realpath ? (host.realpath(path) as Path) : path;
+        }
 
         function getDiagnosticsHelper(
             sourceFile: SourceFile,
@@ -1183,10 +1187,6 @@ namespace ts {
         }
         //name, move below findSourceFile
         function bar(file: SourceFile, fileName: string, path: Path, isDefaultLib: boolean, refFile?: SourceFile, refPos?: number, refEnd?: number) {
-            sourceFilesFoundSearchingNodeModules[path] = (currentNodeModulesDepth > 0);
-            //This sets file.path to the *realpath*
-            file.path = path;
-
             if (host.useCaseSensitiveFileNames()) {
                 // for case-sensitive file systems check if we've already seen some file with similar filename ignoring case
                 const existingFile = filesByNameIgnoreCase.get(path);
@@ -1220,8 +1220,13 @@ namespace ts {
         //!!!
         //fileName is a relative path, thus not a realpath.
         //does getCanonicalFileName need to be an input?
-        function findSourceFile(fileName: string, currentDirectory: string, getCanonicalFileName: (fileName: string) => string, isDefaultLib: boolean, refFile?: SourceFile, refPos?: number, refEnd?: number): SourceFile {
-            const path = toPath(fileName, currentDirectory, getCanonicalFileName); //realpath(...)
+        //TODO: fix up parameters -- resolution and fileName are redundatn
+        function findSourceFile(fileName: string, currentDirectory: string, getCanonicalFileName: (fileName: string) => string, isDefaultLib: boolean, refFile?: SourceFile, refPos?: number, refEnd?: number/*, resolution?: ResolvedModuleFull*/): SourceFile {
+            const originalPath = toPath(fileName, currentDirectory, getCanonicalFileName); //realpath(...)
+            //need resolution.isExternalLibraryImport...
+            const foundSearchingNodeModules = currentNodeModulesDepth > 0;
+                //Support `npm link` scenario -- use real path
+            const path = foundSearchingNodeModules ? realpath(originalPath) : originalPath;
             let fileFromFiles = filesByName.get(path);
             //This might be a symlink.
             //if (!fileFromFiles) {
@@ -1234,6 +1239,12 @@ namespace ts {
             //}
 
             if (fileFromFiles) {
+                //still might need to add realpath
+                //duplicate code
+                if (originalPath !== path) {
+                    symlinkedFiles.set(originalPath, fileFromFiles);
+                }
+
                 return foo(fileFromFiles, fileName, isDefaultLib, refFile, refPos, refEnd);
             }
 
@@ -1249,7 +1260,15 @@ namespace ts {
             });
 
             filesByName.set(path, file);
+            if (originalPath !== path) {
+                //this is needed for getSourceFileByPath to work when given relative paths
+                symlinkedFiles.set(originalPath, file); //!!!
+            }
+
             if (file) {
+                //move these back inside `bar`?
+                sourceFilesFoundSearchingNodeModules[path] = foundSearchingNodeModules;
+                file.path = path;
                 bar(file, fileName, path, isDefaultLib, refFile, refPos, refEnd);
             }
 

src/compiler/utilities.ts

@@ -2551,7 +2551,7 @@ namespace ts {
      * Whether a file should be emitted in a non-`--outFile` case.
      * Don't emit if source file is a declaration file, or was located under node_modules
      */
-    function shouldEmitInDirectory(sourceFile: SourceFile, isSourceFileFromExternalLibrary: (file: SourceFile) => boolean): boolean {
+    export function shouldEmitInDirectory(sourceFile: SourceFile, isSourceFileFromExternalLibrary: (file: SourceFile) => boolean): boolean {
         return isNonDeclarationFile(sourceFile) && !isSourceFileFromExternalLibrary(sourceFile);
     }
 

src/harness/harness.ts

@@ -976,10 +976,10 @@ namespace Harness {
                 }
             }
 
-            //!!! Problem: this may not represent what the command line compiler actually does!!!
+            //!!! Problem: this may not represent what the command line compiler actually does!!! So test in real projects too!
             function getSourceFile(fileName: string) {
                 fileName = ts.normalizePath(fileName);
-                const path = ts.toPath(fileName, currentDirectory, getCanonicalFileName); //was realPath(...)
+                const path = realPath(fileName); //was realPath(...)
                 const fromMap = fileMap.get(path);
                 if (fromMap) {
                     return fromMap();
@@ -1002,7 +1002,7 @@ namespace Harness {
                         Harness.IO.newLine();
 
             //move
-            function realPath(f: ts.Path): ts.Path {
+            function realPath(f: string): ts.Path {
                 const path = ts.toPath(f, currentDirectory, getCanonicalFileName);
                 return realPathMap
                     ? (realPathMap.get(path) as ts.Path) || path

tests/baselines/reference/moduleResolutionWithSymlinks.js

@@ -17,6 +17,14 @@ let y: MyClass2;
 x = y;
 y = x;
 
+//// [/src/library-a/index.js]
+"use strict";
+var MyClass = (function () {
+    function MyClass() {
+    }
+    return MyClass;
+}());
+exports.MyClass = MyClass;
 //// [/src/library-b/index.js]
 "use strict";
 var library_a_1 = require("library-a");

tests/baselines/reference/moduleResolutionWithSymlinks_withOutDir.js

@@ -6,7 +6,7 @@
 export const x = 0;
 
 //// [app.ts]
-import { x } from './shared/abc';
+import { x } from "./shared/abc";
 x + 1;
 
 

tests/baselines/reference/moduleResolutionWithSymlinks_withOutDir.symbols

@@ -1,5 +1,5 @@
 === /src/app.ts ===
-import { x } from './shared/abc';
+import { x } from "./shared/abc";
 >x : Symbol(x, Decl(app.ts, 0, 8))
 
 x + 1;

tests/baselines/reference/moduleResolutionWithSymlinks_withOutDir.types

@@ -1,5 +1,5 @@
 === /src/app.ts ===
-import { x } from './shared/abc';
+import { x } from "./shared/abc";
 >x : 0
 
 x + 1;

tests/cases/compiler/moduleResolutionWithSymlinks.ts

@@ -1,4 +1,3 @@
-// Symlinks for '.ts' files are *not* resolved
 // @module: commonjs
 // @noImplicitReferences: true
 // @traceResolution: true

tests/cases/compiler/moduleResolutionWithSymlinks_withOutDir.ts

@@ -8,7 +8,7 @@
 export const x = 0;
 
 // @filename: /src/app.ts
-import { x } from './shared/abc';
+import { x } from "./shared/abc";
 x + 1;
 
 // @filename: /src/tsconfig.json