From 1d5749ef78ebfb8a15c86c9335f69b231aba7e50 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrewbranch@users.noreply.github.com>
Date: Wed, 22 Jan 2020 13:16:49 -0800
Subject: [PATCH] Fix local and exported type alias merging (#36237)

* Fix local and exported type alias merging

* Add baselines
---
 src/compiler/checker.ts                              |  3 ++-
 .../reference/typeAliasesDoNotMerge.errors.txt       | 12 ++++++++++++
 tests/baselines/reference/typeAliasesDoNotMerge.js   |  8 ++++++++
 .../reference/typeAliasesDoNotMerge.symbols          |  7 +++++++
 .../baselines/reference/typeAliasesDoNotMerge.types  |  7 +++++++
 .../types/typeAliases/typeAliasesDoNotMerge.ts       |  2 ++
 6 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/typeAliasesDoNotMerge.errors.txt
 create mode 100644 tests/baselines/reference/typeAliasesDoNotMerge.js
 create mode 100644 tests/baselines/reference/typeAliasesDoNotMerge.symbols
 create mode 100644 tests/baselines/reference/typeAliasesDoNotMerge.types
 create mode 100644 tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 9a5a7d5b36e..a6e33b763c3 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -29187,7 +29187,7 @@ namespace ts {
             }
         }
 
-        function checkExportsOnMergedDeclarations(node: Node): void {
+        function checkExportsOnMergedDeclarations(node: Declaration): void {
             if (!produceDiagnostics) {
                 return;
             }
@@ -32493,6 +32493,7 @@ namespace ts {
             checkGrammarDecoratorsAndModifiers(node);
 
             checkTypeNameIsReserved(node.name, Diagnostics.Type_alias_name_cannot_be_0);
+            checkExportsOnMergedDeclarations(node);
             checkTypeParameters(node.typeParameters);
             checkSourceElement(node.type);
             registerForUnusedIdentifiersCheck(node);
diff --git a/tests/baselines/reference/typeAliasesDoNotMerge.errors.txt b/tests/baselines/reference/typeAliasesDoNotMerge.errors.txt
new file mode 100644
index 00000000000..0f99dc6326a
--- /dev/null
+++ b/tests/baselines/reference/typeAliasesDoNotMerge.errors.txt
@@ -0,0 +1,12 @@
+tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge.ts(1,13): error TS2395: Individual declarations in merged declaration 'A' must be all exported or all local.
+tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge.ts(2,6): error TS2395: Individual declarations in merged declaration 'A' must be all exported or all local.
+
+
+==== tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge.ts (2 errors) ====
+    export type A = {}
+                ~
+!!! error TS2395: Individual declarations in merged declaration 'A' must be all exported or all local.
+    type A = {}
+         ~
+!!! error TS2395: Individual declarations in merged declaration 'A' must be all exported or all local.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/typeAliasesDoNotMerge.js b/tests/baselines/reference/typeAliasesDoNotMerge.js
new file mode 100644
index 00000000000..e9ec002f237
--- /dev/null
+++ b/tests/baselines/reference/typeAliasesDoNotMerge.js
@@ -0,0 +1,8 @@
+//// [typeAliasesDoNotMerge.ts]
+export type A = {}
+type A = {}
+
+
+//// [typeAliasesDoNotMerge.js]
+"use strict";
+exports.__esModule = true;
diff --git a/tests/baselines/reference/typeAliasesDoNotMerge.symbols b/tests/baselines/reference/typeAliasesDoNotMerge.symbols
new file mode 100644
index 00000000000..94fc3b56651
--- /dev/null
+++ b/tests/baselines/reference/typeAliasesDoNotMerge.symbols
@@ -0,0 +1,7 @@
+=== tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge.ts ===
+export type A = {}
+>A : Symbol(A, Decl(typeAliasesDoNotMerge.ts, 0, 0))
+
+type A = {}
+>A : Symbol(A, Decl(typeAliasesDoNotMerge.ts, 0, 0), Decl(typeAliasesDoNotMerge.ts, 0, 18))
+
diff --git a/tests/baselines/reference/typeAliasesDoNotMerge.types b/tests/baselines/reference/typeAliasesDoNotMerge.types
new file mode 100644
index 00000000000..d949c786def
--- /dev/null
+++ b/tests/baselines/reference/typeAliasesDoNotMerge.types
@@ -0,0 +1,7 @@
+=== tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge.ts ===
+export type A = {}
+>A : import("tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge").A
+
+type A = {}
+>A : import("tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge").A
+
diff --git a/tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge.ts b/tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge.ts
new file mode 100644
index 00000000000..2f5597e410c
--- /dev/null
+++ b/tests/cases/conformance/types/typeAliases/typeAliasesDoNotMerge.ts
@@ -0,0 +1,2 @@
+export type A = {}
+type A = {}