From 4a256abc8a18335f55f8ce21abea9f25c471823f Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Thu, 21 Feb 2019 10:42:38 -0800
Subject: [PATCH] Give a related span pointing to the implementation signature
 when reporting incompatibility.

---
 src/compiler/checker.ts              | 5 ++++-
 src/compiler/diagnosticMessages.json | 4 ++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 53ded49daed..958ceae0395 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -24448,7 +24448,10 @@ namespace ts {
                     const bodySignature = getSignatureFromDeclaration(bodyDeclaration);
                     for (const signature of signatures) {
                         if (!isImplementationCompatibleWithOverload(bodySignature, signature)) {
-                            error(signature.declaration, Diagnostics.This_overload_signature_is_not_compatible_with_its_implementation_signature);
+                            addRelatedInfo(
+                                error(signature.declaration, Diagnostics.This_overload_signature_is_not_compatible_with_its_implementation_signature),
+                                createDiagnosticForNode(bodyDeclaration, Diagnostics.The_implementation_signature_is_declared_here)
+                            );
                             break;
                         }
                     }
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index c0686d10db6..09b0f721292 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -2585,6 +2585,10 @@
         "category": "Error",
         "code": 2749
     },
+    "The implementation signature is declared here.": {
+        "category": "Error",
+        "code": 2750
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",