From 968082a864a767e1f994bfeda300611054707de6 Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk@outlook.com>
Date: Wed, 19 Jun 2024 03:24:22 +0300
Subject: [PATCH] fix(58801): "Move to file" on global code unnecessarily
 imports/exports, generates invalid code (#58811)

---
 src/services/refactors/moveToFile.ts          |  6 ++++-
 ...ile_global.ts => moveToNewFile_global1.ts} |  0
 .../cases/fourslash/moveToNewFile_global2.ts  | 26 +++++++++++++++++++
 .../cases/fourslash/moveToNewFile_global3.ts  | 25 ++++++++++++++++++
 4 files changed, 56 insertions(+), 1 deletion(-)
 rename tests/cases/fourslash/{moveToNewFile_global.ts => moveToNewFile_global1.ts} (100%)
 create mode 100644 tests/cases/fourslash/moveToNewFile_global2.ts
 create mode 100644 tests/cases/fourslash/moveToNewFile_global3.ts

diff --git a/src/services/refactors/moveToFile.ts b/src/services/refactors/moveToFile.ts
index 286b9c2a89533..8f94d31327d4e 100644
--- a/src/services/refactors/moveToFile.ts
+++ b/src/services/refactors/moveToFile.ts
@@ -891,7 +891,7 @@ export function getUsageInfo(oldFile: SourceFile, toMove: readonly Statement[],
     const unusedImportsFromOldFile = new Set<Symbol>();
     for (const statement of toMove) {
         forEachReference(statement, checker, (symbol, isValidTypeOnlyUseSite) => {
-            if (!symbol.declarations) {
+            if (!symbol.declarations || isGlobalType(checker, symbol)) {
                 return;
             }
             if (existingTargetLocals.has(skipAlias(symbol, checker))) {
@@ -952,6 +952,10 @@ export function getUsageInfo(oldFile: SourceFile, toMove: readonly Statement[],
     }
 }
 
+function isGlobalType(checker: TypeChecker, symbol: Symbol) {
+    return !!checker.resolveName(symbol.name, /*location*/ undefined, SymbolFlags.Type, /*excludeGlobals*/ false);
+}
+
 function makeUniqueFilename(proposedFilename: string, extension: string, inDirectory: string, host: LanguageServiceHost): string {
     let newFilename = proposedFilename;
     for (let i = 1;; i++) {
diff --git a/tests/cases/fourslash/moveToNewFile_global.ts b/tests/cases/fourslash/moveToNewFile_global1.ts
similarity index 100%
rename from tests/cases/fourslash/moveToNewFile_global.ts
rename to tests/cases/fourslash/moveToNewFile_global1.ts
diff --git a/tests/cases/fourslash/moveToNewFile_global2.ts b/tests/cases/fourslash/moveToNewFile_global2.ts
new file mode 100644
index 0000000000000..86c1514bb2a00
--- /dev/null
+++ b/tests/cases/fourslash/moveToNewFile_global2.ts
@@ -0,0 +1,26 @@
+/// <reference path='fourslash.ts' />
+
+// @Filename: /a.ts
+////interface String {
+////    reverse(): string;
+////}
+////
+////[|String.prototype.reverse = function (): string {
+////    return this.split("").reverse().join("");
+////}|]
+
+verify.moveToNewFile({
+    newFileContents: {
+        "/a.ts":
+`interface String {
+    reverse(): string;
+}
+
+`,
+        "/newFile.ts":
+`String.prototype.reverse = function(): string {
+    return this.split("").reverse().join("");
+};
+`,
+    }
+});
diff --git a/tests/cases/fourslash/moveToNewFile_global3.ts b/tests/cases/fourslash/moveToNewFile_global3.ts
new file mode 100644
index 0000000000000..6de098af2c561
--- /dev/null
+++ b/tests/cases/fourslash/moveToNewFile_global3.ts
@@ -0,0 +1,25 @@
+/// <reference path='fourslash.ts' />
+
+// @Filename: /a.ts
+////[|// this file extends the string prototype
+////interface String {
+////    reverse(): string;
+////}
+////String.prototype.reverse = function(): string {
+////    return this.split("").reverse().join("");
+////};|]
+
+verify.moveToNewFile({
+    newFileContents: {
+        "/a.ts": "",
+        "/String.ts":
+`// this file extends the string prototype
+interface String {
+    reverse(): string;
+}
+String.prototype.reverse = function(): string {
+    return this.split("").reverse().join("");
+};
+`,
+    }
+});