From 7fbacb495d4b2641af5be36784ba470290d43d62 Mon Sep 17 00:00:00 2001
From: GlassBricks <24237065+GlassBricks@users.noreply.github.com>
Date: Thu, 23 Jun 2022 16:06:40 -0700
Subject: [PATCH] Fix #1295

---
 src/transformation/utils/function-context.ts     | 11 +++++++++--
 test/unit/functions/noImplicitSelfOption.spec.ts | 12 ++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/transformation/utils/function-context.ts b/src/transformation/utils/function-context.ts
index 3a74bce80..896f7e373 100644
--- a/src/transformation/utils/function-context.ts
+++ b/src/transformation/utils/function-context.ts
@@ -79,8 +79,15 @@ export function getDeclarationContextType(
 
     // When using --noImplicitSelf and the signature is defined in a file targeted by the program apply the @noSelf rule.
     const options = program.getCompilerOptions() as CompilerOptions;
-    if (options.noImplicitSelf && program.getSourceFile(signatureDeclaration.getSourceFile().fileName) !== undefined) {
-        return ContextType.Void;
+    if (options.noImplicitSelf) {
+        const sourceFile = program.getSourceFile(signatureDeclaration.getSourceFile().fileName);
+        if (
+            sourceFile !== undefined &&
+            !program.isSourceFileDefaultLibrary(sourceFile) &&
+            !program.isSourceFileFromExternalLibrary(sourceFile)
+        ) {
+            return ContextType.Void;
+        }
     }
 
     // Walk up to find @noSelf or @noSelfInFile
diff --git a/test/unit/functions/noImplicitSelfOption.spec.ts b/test/unit/functions/noImplicitSelfOption.spec.ts
index b68a1ebc9..b2fbdd7d0 100644
--- a/test/unit/functions/noImplicitSelfOption.spec.ts
+++ b/test/unit/functions/noImplicitSelfOption.spec.ts
@@ -35,6 +35,18 @@ test.each(["\\", "/"])("transpileFiles handles paths with noImplicitSelf and %s
     }
 });
 
+test("noImplicitSelf does not affect functions in default libraries", () => {
+    util.testFunction`
+        const array = [1, 2, 3];
+        const items = array.filter(x => x > 1); // array.filter is in external library
+        return items;
+    `
+        .setOptions({
+            noImplicitSelf: true,
+        })
+        .expectToMatchJsResult();
+});
+
 test("enables noSelfInFile behavior for methods", () => {
     util.testFunction`
         class FooBar {