From 845c06692394ea828f24b0264c9a3958d4f6b577 Mon Sep 17 00:00:00 2001
From: Andy <anhans@microsoft.com>
Date: Fri, 3 Nov 2017 17:46:19 -0700
Subject: [PATCH] Check for unused locals in commonjs modules (#19612)

---
 src/compiler/checker.ts                              |  2 +-
 .../reference/commonJsUnusedLocals.errors.txt        |  9 +++++++++
 .../baselines/reference/commonJsUnusedLocals.symbols |  9 +++++++++
 tests/baselines/reference/commonJsUnusedLocals.types | 12 ++++++++++++
 tests/cases/compiler/commonJsUnusedLocals.ts         |  8 ++++++++
 5 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/commonJsUnusedLocals.errors.txt
 create mode 100644 tests/baselines/reference/commonJsUnusedLocals.symbols
 create mode 100644 tests/baselines/reference/commonJsUnusedLocals.types
 create mode 100644 tests/cases/compiler/commonJsUnusedLocals.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index b598be408c1..e2e45b2ccb0 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -23158,7 +23158,7 @@ namespace ts {
 
                 checkDeferredNodes();
 
-                if (isExternalModule(node)) {
+                if (isExternalOrCommonJsModule(node)) {
                     registerForUnusedIdentifiersCheck(node);
                 }
 
diff --git a/tests/baselines/reference/commonJsUnusedLocals.errors.txt b/tests/baselines/reference/commonJsUnusedLocals.errors.txt
new file mode 100644
index 00000000000..b8e2159d432
--- /dev/null
+++ b/tests/baselines/reference/commonJsUnusedLocals.errors.txt
@@ -0,0 +1,9 @@
+/a.js(1,7): error TS6133: 'x' is declared but its value is never read.
+
+
+==== /a.js (1 errors) ====
+    const x = 0;
+          ~
+!!! error TS6133: 'x' is declared but its value is never read.
+    exports.y = 1;
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/commonJsUnusedLocals.symbols b/tests/baselines/reference/commonJsUnusedLocals.symbols
new file mode 100644
index 00000000000..08155bc4d26
--- /dev/null
+++ b/tests/baselines/reference/commonJsUnusedLocals.symbols
@@ -0,0 +1,9 @@
+=== /a.js ===
+const x = 0;
+>x : Symbol(x, Decl(a.js, 0, 5))
+
+exports.y = 1;
+>exports.y : Symbol(y, Decl(a.js, 0, 12))
+>exports : Symbol(y, Decl(a.js, 0, 12))
+>y : Symbol(y, Decl(a.js, 0, 12))
+
diff --git a/tests/baselines/reference/commonJsUnusedLocals.types b/tests/baselines/reference/commonJsUnusedLocals.types
new file mode 100644
index 00000000000..e792ad8e782
--- /dev/null
+++ b/tests/baselines/reference/commonJsUnusedLocals.types
@@ -0,0 +1,12 @@
+=== /a.js ===
+const x = 0;
+>x : 0
+>0 : 0
+
+exports.y = 1;
+>exports.y = 1 : 1
+>exports.y : number
+>exports : typeof "/a"
+>y : number
+>1 : 1
+
diff --git a/tests/cases/compiler/commonJsUnusedLocals.ts b/tests/cases/compiler/commonJsUnusedLocals.ts
new file mode 100644
index 00000000000..d1b51aa245b
--- /dev/null
+++ b/tests/cases/compiler/commonJsUnusedLocals.ts
@@ -0,0 +1,8 @@
+// @noUnusedLocals: true
+// @allowJs: true
+// @checkJs: true
+// @noEmit: true
+
+// @Filename: /a.js
+const x = 0;
+exports.y = 1;