From 67f55aabd7d330a792c08d84563d29db87c4788a Mon Sep 17 00:00:00 2001
From: Eli Barzilay <eli@barzilay.org>
Date: Mon, 22 Feb 2021 18:30:17 -0500
Subject: [PATCH] Extend the `MetaProperty` check to work for `new.target` too

---
 src/compiler/checker.ts                       |  6 ++--
 .../baselines/reference/newTargetNarrowing.js | 21 ++++++++++++
 .../reference/newTargetNarrowing.symbols      | 24 +++++++++++++
 .../reference/newTargetNarrowing.types        | 34 +++++++++++++++++++
 .../es6/newTarget/newTargetNarrowing.ts       | 12 +++++++
 5 files changed, 93 insertions(+), 4 deletions(-)
 create mode 100644 tests/baselines/reference/newTargetNarrowing.js
 create mode 100644 tests/baselines/reference/newTargetNarrowing.symbols
 create mode 100644 tests/baselines/reference/newTargetNarrowing.types
 create mode 100644 tests/cases/conformance/es6/newTarget/newTargetNarrowing.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 8bcd277cd1e..2237fe2cda0 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -21322,10 +21322,8 @@ namespace ts {
             switch (source.kind) {
                 case SyntaxKind.MetaProperty:
                     return target.kind === SyntaxKind.MetaProperty
-                        && (source as MetaProperty).keywordToken === SyntaxKind.ImportKeyword
-                        && (target as MetaProperty).keywordToken === SyntaxKind.ImportKeyword
-                        && (source as MetaProperty).name.escapedText === "meta"
-                        && (target as MetaProperty).name.escapedText === "meta";
+                        && (source as MetaProperty).keywordToken === (target as MetaProperty).keywordToken
+                        && (source as MetaProperty).name.escapedText === (target as MetaProperty).name.escapedText;
                 case SyntaxKind.Identifier:
                 case SyntaxKind.PrivateIdentifier:
                     return target.kind === SyntaxKind.Identifier && getResolvedSymbol(<Identifier>source) === getResolvedSymbol(<Identifier>target) ||
diff --git a/tests/baselines/reference/newTargetNarrowing.js b/tests/baselines/reference/newTargetNarrowing.js
new file mode 100644
index 00000000000..357955aa906
--- /dev/null
+++ b/tests/baselines/reference/newTargetNarrowing.js
@@ -0,0 +1,21 @@
+//// [newTargetNarrowing.ts]
+function foo(x: true) { }
+
+function f() {
+  if (new.target.marked === true) {
+    foo(new.target.marked);
+  }
+}
+
+f.marked = true;
+
+
+//// [newTargetNarrowing.js]
+"use strict";
+function foo(x) { }
+function f() {
+    if (new.target.marked === true) {
+        foo(new.target.marked);
+    }
+}
+f.marked = true;
diff --git a/tests/baselines/reference/newTargetNarrowing.symbols b/tests/baselines/reference/newTargetNarrowing.symbols
new file mode 100644
index 00000000000..ed180bbc059
--- /dev/null
+++ b/tests/baselines/reference/newTargetNarrowing.symbols
@@ -0,0 +1,24 @@
+=== tests/cases/conformance/es6/newTarget/newTargetNarrowing.ts ===
+function foo(x: true) { }
+>foo : Symbol(foo, Decl(newTargetNarrowing.ts, 0, 0))
+>x : Symbol(x, Decl(newTargetNarrowing.ts, 0, 13))
+
+function f() {
+>f : Symbol(f, Decl(newTargetNarrowing.ts, 0, 25), Decl(newTargetNarrowing.ts, 6, 1))
+
+  if (new.target.marked === true) {
+>new.target.marked : Symbol(f.marked, Decl(newTargetNarrowing.ts, 6, 1))
+>marked : Symbol(f.marked, Decl(newTargetNarrowing.ts, 6, 1))
+
+    foo(new.target.marked);
+>foo : Symbol(foo, Decl(newTargetNarrowing.ts, 0, 0))
+>new.target.marked : Symbol(f.marked, Decl(newTargetNarrowing.ts, 6, 1))
+>marked : Symbol(f.marked, Decl(newTargetNarrowing.ts, 6, 1))
+  }
+}
+
+f.marked = true;
+>f.marked : Symbol(f.marked, Decl(newTargetNarrowing.ts, 6, 1))
+>f : Symbol(f, Decl(newTargetNarrowing.ts, 0, 25), Decl(newTargetNarrowing.ts, 6, 1))
+>marked : Symbol(f.marked, Decl(newTargetNarrowing.ts, 6, 1))
+
diff --git a/tests/baselines/reference/newTargetNarrowing.types b/tests/baselines/reference/newTargetNarrowing.types
new file mode 100644
index 00000000000..df118a4982d
--- /dev/null
+++ b/tests/baselines/reference/newTargetNarrowing.types
@@ -0,0 +1,34 @@
+=== tests/cases/conformance/es6/newTarget/newTargetNarrowing.ts ===
+function foo(x: true) { }
+>foo : (x: true) => void
+>x : true
+>true : true
+
+function f() {
+>f : typeof f
+
+  if (new.target.marked === true) {
+>new.target.marked === true : boolean
+>new.target.marked : boolean
+>new.target : typeof f
+>target : any
+>marked : boolean
+>true : true
+
+    foo(new.target.marked);
+>foo(new.target.marked) : void
+>foo : (x: true) => void
+>new.target.marked : true
+>new.target : typeof f
+>target : any
+>marked : true
+  }
+}
+
+f.marked = true;
+>f.marked = true : true
+>f.marked : boolean
+>f : typeof f
+>marked : boolean
+>true : true
+
diff --git a/tests/cases/conformance/es6/newTarget/newTargetNarrowing.ts b/tests/cases/conformance/es6/newTarget/newTargetNarrowing.ts
new file mode 100644
index 00000000000..b17ada373e3
--- /dev/null
+++ b/tests/cases/conformance/es6/newTarget/newTargetNarrowing.ts
@@ -0,0 +1,12 @@
+// @target: es6
+// @strict: true
+
+function foo(x: true) { }
+
+function f() {
+  if (new.target.marked === true) {
+    foo(new.target.marked);
+  }
+}
+
+f.marked = true;