From 9f9825a4f062d9e6b61858acc8394a51653ef9ee Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Date: Thu, 25 Feb 2021 15:21:41 -0800
Subject: [PATCH] Fix: checkAliasSymbol crash when checking for @deprecated

It's possible that we shouldn't be creating symbol with no declarations
from non-homomorphic mapped types, but for 4.2, the right fix is to make
the @deprecated-check in checkAliasSymbol ensure that
target.declarations is defined.
---
 src/compiler/checker.ts                       |  2 +-
 .../reference/importPropertyFromMappedType.js | 16 ++++++++++++++
 .../importPropertyFromMappedType.symbols      | 21 +++++++++++++++++++
 .../importPropertyFromMappedType.types        | 17 +++++++++++++++
 .../compiler/importPropertyFromMappedType.ts  | 11 ++++++++++
 5 files changed, 66 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/importPropertyFromMappedType.js
 create mode 100644 tests/baselines/reference/importPropertyFromMappedType.symbols
 create mode 100644 tests/baselines/reference/importPropertyFromMappedType.types
 create mode 100644 tests/cases/compiler/importPropertyFromMappedType.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 8f159f198fbb1..1ef57f9b843c9 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -37124,7 +37124,7 @@ namespace ts {
                     error(node, Diagnostics.Re_exporting_a_type_when_the_isolatedModules_flag_is_provided_requires_using_export_type);
                 }
 
-                if (isImportSpecifier(node) && every(target.declarations, d => !!(getCombinedNodeFlags(d) & NodeFlags.Deprecated))) {
+                if (isImportSpecifier(node) && target.declarations?.every(d => !!(getCombinedNodeFlags(d) & NodeFlags.Deprecated))) {
                     addDeprecatedSuggestion(node.name, target.declarations, symbol.escapedName as string);
                 }
             }
diff --git a/tests/baselines/reference/importPropertyFromMappedType.js b/tests/baselines/reference/importPropertyFromMappedType.js
new file mode 100644
index 0000000000000..ec31897f0f20b
--- /dev/null
+++ b/tests/baselines/reference/importPropertyFromMappedType.js
@@ -0,0 +1,16 @@
+//// [tests/cases/compiler/importPropertyFromMappedType.ts] ////
+
+//// [errors.d.ts]
+export = createHttpError;
+declare const createHttpError: createHttpError.NamedConstructors;
+declare namespace createHttpError {
+    type NamedConstructors =  { [P in 'NotFound']: unknown;}
+}
+
+//// [main.ts]
+import { NotFound } from './errors'
+
+
+//// [main.js]
+"use strict";
+exports.__esModule = true;
diff --git a/tests/baselines/reference/importPropertyFromMappedType.symbols b/tests/baselines/reference/importPropertyFromMappedType.symbols
new file mode 100644
index 0000000000000..2b847049346d3
--- /dev/null
+++ b/tests/baselines/reference/importPropertyFromMappedType.symbols
@@ -0,0 +1,21 @@
+=== tests/cases/compiler/errors.d.ts ===
+export = createHttpError;
+>createHttpError : Symbol(createHttpError, Decl(errors.d.ts, 1, 13), Decl(errors.d.ts, 1, 65))
+
+declare const createHttpError: createHttpError.NamedConstructors;
+>createHttpError : Symbol(createHttpError, Decl(errors.d.ts, 1, 13), Decl(errors.d.ts, 1, 65))
+>createHttpError : Symbol(createHttpError, Decl(errors.d.ts, 1, 13), Decl(errors.d.ts, 1, 65))
+>NamedConstructors : Symbol(createHttpError.NamedConstructors, Decl(errors.d.ts, 2, 35))
+
+declare namespace createHttpError {
+>createHttpError : Symbol(createHttpError, Decl(errors.d.ts, 1, 13), Decl(errors.d.ts, 1, 65))
+
+    type NamedConstructors =  { [P in 'NotFound']: unknown;}
+>NamedConstructors : Symbol(NamedConstructors, Decl(errors.d.ts, 2, 35))
+>P : Symbol(P, Decl(errors.d.ts, 3, 33))
+}
+
+=== tests/cases/compiler/main.ts ===
+import { NotFound } from './errors'
+>NotFound : Symbol(NotFound, Decl(main.ts, 0, 8))
+
diff --git a/tests/baselines/reference/importPropertyFromMappedType.types b/tests/baselines/reference/importPropertyFromMappedType.types
new file mode 100644
index 0000000000000..7cd7b0278aa92
--- /dev/null
+++ b/tests/baselines/reference/importPropertyFromMappedType.types
@@ -0,0 +1,17 @@
+=== tests/cases/compiler/errors.d.ts ===
+export = createHttpError;
+>createHttpError : createHttpError.NamedConstructors
+
+declare const createHttpError: createHttpError.NamedConstructors;
+>createHttpError : createHttpError.NamedConstructors
+>createHttpError : any
+
+declare namespace createHttpError {
+    type NamedConstructors =  { [P in 'NotFound']: unknown;}
+>NamedConstructors : NamedConstructors
+}
+
+=== tests/cases/compiler/main.ts ===
+import { NotFound } from './errors'
+>NotFound : unknown
+
diff --git a/tests/cases/compiler/importPropertyFromMappedType.ts b/tests/cases/compiler/importPropertyFromMappedType.ts
new file mode 100644
index 0000000000000..ad80aba2d0a50
--- /dev/null
+++ b/tests/cases/compiler/importPropertyFromMappedType.ts
@@ -0,0 +1,11 @@
+// #
+
+// @filename: errors.d.ts
+export = createHttpError;
+declare const createHttpError: createHttpError.NamedConstructors;
+declare namespace createHttpError {
+    type NamedConstructors =  { [P in 'NotFound']: unknown;}
+}
+
+// @filename: main.ts
+import { NotFound } from './errors'