test(tsc): Symlinked projects or the ones with symlinked parents should work

tsc/internal/execute/tsctests/tscbuild_test.go

@@ -9,6 +9,8 @@ import (
 	"time"
 
 	"github.com/microsoft/TypeScript/tsc/internal/core"
+	"github.com/microsoft/TypeScript/tsc/internal/execute"
+	"github.com/microsoft/TypeScript/tsc/internal/execute/tsc"
 	"github.com/microsoft/TypeScript/tsc/internal/testutil/contentmappertest"
 	"github.com/microsoft/TypeScript/tsc/internal/testutil/harnessutil"
 	"github.com/microsoft/TypeScript/tsc/internal/testutil/stringtestutil"
@@ -4788,3 +4790,110 @@ func TestBuildProjectReferenceRedirectWithMultipleSubProjects(t *testing.T) {
 		test.run(t, "projectReferenceRedirect")
 	}
 }
+
+func TestBuildWithSymlinkedCurrentDirectory(t *testing.T) {
+	t.Parallel()
+
+	buildFiles := func(root string) FileMap {
+		return FileMap{
+			root + "/lib/tsconfig.json": stringtestutil.Dedent(`
+				{
+					"compilerOptions": { "composite": true, "outDir": "./dist", "rootDir": "./" },
+					"include": ["./index.ts"]
+				}`),
+			root + "/lib/package.json": stringtestutil.Dedent(`
+				{
+					"name": "lib",
+					"version": "1.0.0",
+					"type": "module",
+					"exports": { ".": "./index.ts" }
+				}`),
+			root + "/lib/index.ts": stringtestutil.Dedent(`
+				declare const Something: unique symbol;
+				export interface Duration {
+					readonly [Something]: "Duration";
+				}
+				export declare const dur2: Duration;`),
+			root + "/app/tsconfig.json": stringtestutil.Dedent(`
+				{
+					"compilerOptions": { "composite": true, "outDir": "./dist", "rootDir": "./" },
+					"include": ["./index.ts"],
+					"references": [{ "path": "../lib" }]
+				}`),
+			root + "/app/index.ts": stringtestutil.Dedent(`
+				import type { Duration } from "lib";
+				export declare const dur1: Duration`),
+			root + "/app/node_modules/lib": vfstest.Symlink(root + "/lib"),
+			root + "/check.ts": stringtestutil.Dedent(`
+				import { dur1 } from "app";
+				import { dur2 } from "lib";
+
+				console.log(dur1 === dur2)`),
+			root + "/tsconfig.json": stringtestutil.Dedent(`
+				{
+					"include": ["check.ts"],
+					"references": [{ "path": "./lib" }, { "path": "./app" }],
+					"compilerOptions": {
+						"composite": true,
+						"noEmit": true,
+						"paths": { "lib": ["./lib/index.ts"], "app": ["./app/index.ts"] }
+					}
+				}`),
+		}
+	}
+
+	withLinks := func(files FileMap, links map[string]string) FileMap {
+		for path, target := range links {
+			files[path] = vfstest.Symlink(target)
+		}
+		return files
+	}
+
+	for _, test := range []struct {
+		name  string
+		files FileMap
+		cwd   string
+	}{
+		{
+			name:  "real path",
+			files: buildFiles("/home/alice/workspaces/project"),
+			cwd:   "/home/alice/workspaces/project",
+		},
+		{
+			name: "current directory is the symlink",
+			files: withLinks(buildFiles("/home/alice/workspaces/project"), map[string]string{
+				"/home/alice/workspaces/symlinked": "/home/alice/workspaces/project",
+			}),
+			cwd: "/home/alice/workspaces/symlinked",
+		},
+		{
+			name: "parent directory is the symlink",
+			files: withLinks(buildFiles("/home/bob/projects/playground-app"), map[string]string{
+				"/home/alice/projects": "/home/bob/projects",
+			}),
+			cwd: "/home/alice/projects/playground-app",
+		},
+		{
+			name: "symlinked ancestor reached through a symlink chain",
+			files: withLinks(buildFiles("/home/bob/projects/playground-app"), map[string]string{
+				"/home/alice/aliased":        "/home/bob/projects",
+				"/home/alice/nested/aliased": "/home/alice/aliased",
+			}),
+			cwd: "/home/alice/nested/aliased/playground-app",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+			sys := newTestSys(&tscInput{files: test.files, cwd: test.cwd}, false)
+			result := execute.CommandLine(t.Context(), sys, []string{"-b"}, sys)
+			assert.Equal(
+				t,
+				result.Status,
+				tsc.ExitStatusSuccess,
+				"building via %s should succeed:\n%s",
+				test.cwd,
+				sys.currentWrite.String(),
+			)
+		})
+	}
+}

tsc/internal/vfs/vfstest/vfstest.go

@@ -605,14 +605,13 @@ func (m *MapFS) Remove(path string) error {
 func (m *MapFS) Chtimes(path string, aTime time.Time, mTime time.Time) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
-	canonical := m.getCanonicalPath(path)
-	canonicalString := string(canonical)
-	fileInfo := m.m[canonicalString]
-	if fileInfo == nil {
-		// file does not exist
-		return fs.ErrNotExist
+
+	// Like [os.Chtimes], follow symlinks, including symlinked parent directories.
+	file, _, err := m.getFollowingSymlinks(m.getCanonicalPath(path))
+	if err != nil {
+		return err
 	}
-	fileInfo.ModTime = mTime
+	file.ModTime = mTime
 	return nil
 }
 

tsc/internal/vfs/vfstest/vfstest_test.go

@@ -9,6 +9,7 @@ import (
 	"sync"
 	"testing"
 	"testing/fstest"
+	"time"
 	"unicode/utf16"
 
 	"github.com/microsoft/TypeScript/tsc/internal/testutil"
@@ -658,6 +659,27 @@ func TestWritableFSSymlink(t *testing.T) {
 	assert.Equal(t, content, "hello, world")
 }
 
+func TestChtimesFollowsSymlinks(t *testing.T) {
+	t.Parallel()
+
+	fsys := FromMap(map[string]any{
+		"/some/dir/a.ts": "hello, world",
+		"/some/dirlink":  Symlink("/some/dir"),
+		"/real.ts":       "hello, world",
+		"/link.ts":       Symlink("/real.ts"),
+	}, false)
+
+	modified := time.Unix(123, 0)
+
+	assert.NilError(t, fsys.Chtimes("/some/dirlink/a.ts", modified, modified))
+	assert.Equal(t, fsys.Stat("/some/dir/a.ts").ModTime(), modified)
+
+	assert.NilError(t, fsys.Chtimes("/link.ts", modified, modified))
+	assert.Equal(t, fsys.Stat("/real.ts").ModTime(), modified)
+
+	assert.ErrorIs(t, fsys.Chtimes("/missing.ts", modified, modified), fs.ErrNotExist)
+}
+
 func TestWritableFSSymlinkChain(t *testing.T) {
 	t.Parallel()