From 98f8ec5d5a3bdf4e59bf87686125f14519314657 Mon Sep 17 00:00:00 2001
From: Jason Freeman <jfreeman@microsoft.com>
Date: Tue, 7 Oct 2014 15:36:55 -0700
Subject: [PATCH 1/3] Fix crash when getting member completion for an object
 literal

---
 src/services/services.ts | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/services/services.ts b/src/services/services.ts
index e4d28f4700f..b4522849e2a 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -2144,9 +2144,16 @@ module ts {
             }
 
             // TODO: this is a hack for now, we need a proper walking mechanism to verify that we have the correct node
-            var mappedNode = getTouchingToken(sourceFile, TypeScript.end(node) - 1);
-            if (isPunctuation(mappedNode.kind)) {
-                mappedNode = mappedNode.parent;
+            var precedingToken = findTokenOnLeftOfPosition(sourceFile, TypeScript.end(node));
+            var mappedNode: Node;
+            if (!precedingToken) {
+                mappedNode = sourceFile;
+            }
+            else if (isPunctuation(precedingToken.kind)) {
+                mappedNode = precedingToken.parent;
+            }
+            else {
+                mappedNode = precedingToken;
             }
 
             Debug.assert(mappedNode, "Could not map a Fidelity node to an AST node");

From a8a1fa27d85440f5dce5648275472a0dd0ab5386 Mon Sep 17 00:00:00 2001
From: Mohamed Hegazy <mhegazy@microsoft.com>
Date: Wed, 8 Oct 2014 15:47:30 -0700
Subject: [PATCH 2/3] Try to pick a good signature, if no signature matches

---
 src/compiler/checker.ts                         | 17 ++++++++++++++++-
 src/compiler/types.ts                           |  3 ++-
 ...bjectLiteralThatIsParameterOfFunctionCall.ts | 11 +++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)
 create mode 100644 tests/cases/fourslash/completionListInObjectLiteralThatIsParameterOfFunctionCall.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 33d4008885d..4a05021ce15 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -4508,8 +4508,23 @@ module ts {
             }
             else {
                 error(node, Diagnostics.Supplied_parameters_do_not_match_any_signature_of_call_target);
-                return resolveErrorCall(node);
             }
+
+            // No signature was applicable. We have already reported the errors for the invalid signature.
+            // If this is a type resolution session, e.g. Language Service, try to get better information that anySignature.
+            // Pick the first candidate that matches the arity. This way we can get a contextual type for cases like:
+            //  declare function f(a: { xa: number; xb: number; });
+            //  f({ |
+            if (!fullTypeCheck) {
+                if (candidates.length) {
+                    for (var i = 0; i < candidates.length; i++) {
+                        if (signatureHasCorrectArity(node, candidates[i])) {
+                            return candidates[i];
+                        }
+                    }
+                }
+            }
+
             return resolveErrorCall(node);
 
             // The candidate list orders groups in reverse, but within a group signatures are kept in declaration order
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index da2cb9099c2..ee6ad334b3d 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -1204,7 +1204,8 @@ module ts {
         }
 
         public static toString(parts: SymbolDisplayPart[]) {
-            return parts.map(p => p.text).join("");
+            var result = map(parts, p => p.text);
+            return result ? result.join("") : "";
         }
     }
 
diff --git a/tests/cases/fourslash/completionListInObjectLiteralThatIsParameterOfFunctionCall.ts b/tests/cases/fourslash/completionListInObjectLiteralThatIsParameterOfFunctionCall.ts
new file mode 100644
index 00000000000..9dcf7456226
--- /dev/null
+++ b/tests/cases/fourslash/completionListInObjectLiteralThatIsParameterOfFunctionCall.ts
@@ -0,0 +1,11 @@
+/// <reference path='fourslash.ts'/>
+
+////function f(a: { xa: number; xb: number; }) { }
+////var xc;
+////f({
+////    /**/
+
+goTo.marker()
+verify.memberListContains('xa');
+verify.memberListContains('xb');
+verify.memberListCount(2);
\ No newline at end of file

From 2e9a20f8ce59289a5603385bc71538a2b09613d1 Mon Sep 17 00:00:00 2001
From: Mohamed Hegazy <mhegazy@microsoft.com>
Date: Wed, 8 Oct 2014 17:29:14 -0700
Subject: [PATCH 3/3] Respond to code review comments

---
 src/compiler/checker.ts | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 4a05021ce15..68011b586f2 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -4516,11 +4516,9 @@ module ts {
             //  declare function f(a: { xa: number; xb: number; });
             //  f({ |
             if (!fullTypeCheck) {
-                if (candidates.length) {
-                    for (var i = 0; i < candidates.length; i++) {
-                        if (signatureHasCorrectArity(node, candidates[i])) {
-                            return candidates[i];
-                        }
+                for (var i = 0, n = candidates.length; i < n; i++) {
+                    if (signatureHasCorrectArity(node, candidates[i])) {
+                        return candidates[i];
                     }
                 }
             }