From 4d436828dda5a7b2fcebf6d1c6331e2972fb530a Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Date: Thu, 5 Apr 2018 09:37:26 -0700
Subject: [PATCH 1/2] Fix crash in type resolution in JS IIFEs

We recognise IIFEs as JS special assignment initialisers, but not as
containers otherwise. That means that IIFEs will not have a symbol
unless they have an *outside* assignment.

The permanent fix will be to make IIFEs a container, based on the
containership of the value that they return. This fix does not do that;
it just makes type resolution return undefined instead of crashing.
---
 src/compiler/checker.ts                            |  3 +++
 tests/baselines/reference/typeLookupInIIFE.symbols |  9 +++++++++
 tests/baselines/reference/typeLookupInIIFE.types   | 12 ++++++++++++
 tests/cases/conformance/salsa/typeLookupInIIFE.ts  |  9 +++++++++
 4 files changed, 33 insertions(+)
 create mode 100644 tests/baselines/reference/typeLookupInIIFE.symbols
 create mode 100644 tests/baselines/reference/typeLookupInIIFE.types
 create mode 100644 tests/cases/conformance/salsa/typeLookupInIIFE.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 076830b47f851..e370ca59ed8a6 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -2063,6 +2063,9 @@ namespace ts {
                     if (initializer) {
                         namespace = getSymbolOfNode(initializer);
                     }
+                    if (!namespace) {
+                        return undefined;
+                    }
                     if (namespace.valueDeclaration &&
                         isVariableDeclaration(namespace.valueDeclaration) &&
                         namespace.valueDeclaration.initializer &&
diff --git a/tests/baselines/reference/typeLookupInIIFE.symbols b/tests/baselines/reference/typeLookupInIIFE.symbols
new file mode 100644
index 0000000000000..1324328027428
--- /dev/null
+++ b/tests/baselines/reference/typeLookupInIIFE.symbols
@@ -0,0 +1,9 @@
+=== tests/cases/conformance/salsa/a.js ===
+// #22973
+var ns = (function() {})();
+>ns : Symbol(ns, Decl(a.js, 1, 3))
+
+/** @type {ns.NotFound} */
+var crash;
+>crash : Symbol(crash, Decl(a.js, 3, 3))
+
diff --git a/tests/baselines/reference/typeLookupInIIFE.types b/tests/baselines/reference/typeLookupInIIFE.types
new file mode 100644
index 0000000000000..83289c4b21413
--- /dev/null
+++ b/tests/baselines/reference/typeLookupInIIFE.types
@@ -0,0 +1,12 @@
+=== tests/cases/conformance/salsa/a.js ===
+// #22973
+var ns = (function() {})();
+>ns : void
+>(function() {})() : void
+>(function() {}) : () => void
+>function() {} : () => void
+
+/** @type {ns.NotFound} */
+var crash;
+>crash : any
+
diff --git a/tests/cases/conformance/salsa/typeLookupInIIFE.ts b/tests/cases/conformance/salsa/typeLookupInIIFE.ts
new file mode 100644
index 0000000000000..52b76db639252
--- /dev/null
+++ b/tests/cases/conformance/salsa/typeLookupInIIFE.ts
@@ -0,0 +1,9 @@
+// @noEmit: true
+// @allowJs: true
+// @checkJs: true
+// @noImplicitAny: true
+// @Filename: a.js
+// #22973
+var ns = (function() {})();
+/** @type {ns.NotFound} */
+var crash;

From da781ba5be99ebc9a2c7f3fd6bf569800c8686be Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Date: Thu, 5 Apr 2018 09:45:40 -0700
Subject: [PATCH 2/2] Comment the IIFE-fix line

---
 src/compiler/checker.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index e370ca59ed8a6..811dbdcbc3d25 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -2063,6 +2063,7 @@ namespace ts {
                     if (initializer) {
                         namespace = getSymbolOfNode(initializer);
                     }
+                    // Currently, IIFEs may not have a symbol and we don't know about their contents. Give up in this case.
                     if (!namespace) {
                         return undefined;
                     }