From c5e6913edea3da168929732c8ee0ba75de0f661c Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Thu, 25 Apr 2019 15:44:23 -0700
Subject: [PATCH] Add grammar error on quoted constructors for TS 3.5

---
 src/compiler/checker.ts                       |  3 +++
 src/compiler/diagnosticMessages.json          |  6 ++++-
 .../quotedConstructors.ts                     | 24 +++++++------------
 3 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index ce56db4b962f4..da002607ed82c 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -31468,6 +31468,9 @@ namespace ts {
                         return grammarErrorAtPos(node, node.end - 1, ";".length, Diagnostics._0_expected, "{");
                     }
                 }
+                else if (isClassLike(node.parent) && isStringLiteral(node.name) && node.name.text === "constructor" && (!compilerOptions.target || compilerOptions.target < ScriptTarget.ES5)) {
+                    return grammarErrorOnNode(node.name, Diagnostics.Quoted_constructors_have_previously_been_interpreted_as_methods_which_is_incorrect_In_TypeScript_3_6_they_will_be_correctly_parsed_as_constructors_In_the_meantime_consider_using_constructor_to_write_a_constructor_or_constructor_to_write_a_method);
+                }
                 if (checkGrammarForGenerator(node)) {
                     return true;
                 }
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index a78e89f42beb3..34d093caea23a 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -2959,7 +2959,7 @@
         "category": "Error",
         "code": 4104
     },
-    
+
     "The current host does not support the '{0}' option.": {
         "category": "Error",
         "code": 5001
@@ -4954,5 +4954,9 @@
     "No value exists in scope for the shorthand property '{0}'. Either declare one or provide an initializer." :{
         "category": "Error",
         "code": 18004
+    },
+    "Quoted constructors have previously been interpreted as methods, which is incorrect. In TypeScript 3.6, they will be correctly parsed as constructors. In the meantime, consider using 'constructor()' to write a constructor, or '[\"constructor\"]()' to write a method.": {
+        "category": "Error",
+        "code": 96000
     }
 }
diff --git a/tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts b/tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts
index e0564ba73ec54..3ab45c72810cd 100644
--- a/tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts
+++ b/tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts
@@ -1,23 +1,17 @@
 class C {
-    x: number;
-    "constructor"() {
-        this.x = 0;
-    }
+    "constructor"() {} // Error in 3.5
 }
-(new C).constructor(); // Error
 
 class D {
-    x: number;
-    'constructor'() {
-        this.x = 0;
-    }
+    'constructor'() {} // Error in 3.5
 }
-(new C).constructor(); // Error
 
 class E {
-    x: number;
-    ['constructor']() {
-        this.x = 0;
-    }
+    ['constructor']() {}
 }
-(new E).constructor();
+
+new class {
+    "constructor"() {} // Error in 3.5
+};
+
+var o = { "constructor"() {} };