From 3c8732fab1cdc524c1cf3a506bda871b09842199 Mon Sep 17 00:00:00 2001
From: Charles Pierce <cpierce.grad@gmail.com>
Date: Wed, 10 May 2017 17:26:47 -0700
Subject: [PATCH 1/2] Prevent Duplicate String Literal Completions

---
 src/services/completions.ts                   | 23 +++++++++++--------
 .../fourslash/completionForStringLiteral12.ts | 10 ++++++++
 2 files changed, 24 insertions(+), 9 deletions(-)
 create mode 100644 tests/cases/fourslash/completionForStringLiteral12.ts

diff --git a/src/services/completions.ts b/src/services/completions.ts
index 318c02683ff..948d7349419 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -221,11 +221,12 @@ namespace ts.Completions {
     function getStringLiteralCompletionEntriesFromCallExpression(argumentInfo: SignatureHelp.ArgumentListInfo, typeChecker: TypeChecker): CompletionInfo | undefined {
         const candidates: Signature[] = [];
         const entries: CompletionEntry[] = [];
+        const uniques = createMap<string>();
 
         typeChecker.getResolvedSignature(argumentInfo.invocation, candidates);
 
         for (const candidate of candidates) {
-            addStringLiteralCompletionsFromType(typeChecker.getParameterType(candidate, argumentInfo.argumentIndex), entries, typeChecker);
+            addStringLiteralCompletionsFromType(typeChecker.getParameterType(candidate, argumentInfo.argumentIndex), entries, typeChecker, uniques);
         }
 
         if (entries.length) {
@@ -258,7 +259,7 @@ namespace ts.Completions {
         return undefined;
     }
 
-    function addStringLiteralCompletionsFromType(type: Type, result: Push<CompletionEntry>, typeChecker: TypeChecker): void {
+    function addStringLiteralCompletionsFromType(type: Type, result: Push<CompletionEntry>, typeChecker: TypeChecker, uniques = createMap<string>()): void {
         if (type && type.flags & TypeFlags.TypeParameter) {
             type = typeChecker.getBaseConstraintOfType(type);
         }
@@ -267,16 +268,20 @@ namespace ts.Completions {
         }
         if (type.flags & TypeFlags.Union) {
             for (const t of (<UnionType>type).types) {
-                addStringLiteralCompletionsFromType(t, result, typeChecker);
+                addStringLiteralCompletionsFromType(t, result, typeChecker, uniques);
             }
         }
         else if (type.flags & TypeFlags.StringLiteral) {
-            result.push({
-                name: (<LiteralType>type).text,
-                kindModifiers: ScriptElementKindModifier.none,
-                kind: ScriptElementKind.variableElement,
-                sortText: "0"
-            });
+            const name = (<LiteralType>type).text;
+            if (!uniques.get(name)) {
+                uniques.set(name, name);
+                result.push({
+                    name,
+                    kindModifiers: ScriptElementKindModifier.none,
+                    kind: ScriptElementKind.variableElement,
+                    sortText: "0"
+                });
+            }
         }
     }
 
diff --git a/tests/cases/fourslash/completionForStringLiteral12.ts b/tests/cases/fourslash/completionForStringLiteral12.ts
new file mode 100644
index 00000000000..22bb2f00a43
--- /dev/null
+++ b/tests/cases/fourslash/completionForStringLiteral12.ts
@@ -0,0 +1,10 @@
+/// <reference path='fourslash.ts' />
+
+////function foo(x: "bla"): void;
+////function foo(x: "bla"): void;
+////function foo(x: string) {}
+////foo("/**/")
+
+goTo.marker();
+verify.completionListContains("bla");
+verify.completionListCount(1);

From cff19ab3d3fc2cb8d405a9c435b364b5b81985c8 Mon Sep 17 00:00:00 2001
From: Charles Pierce <cpierce.grad@gmail.com>
Date: Thu, 11 May 2017 10:42:25 -0700
Subject: [PATCH 2/2] Switch map to be used as a set rather than a map

---
 src/services/completions.ts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/services/completions.ts b/src/services/completions.ts
index 948d7349419..e850bfb4496 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -221,7 +221,7 @@ namespace ts.Completions {
     function getStringLiteralCompletionEntriesFromCallExpression(argumentInfo: SignatureHelp.ArgumentListInfo, typeChecker: TypeChecker): CompletionInfo | undefined {
         const candidates: Signature[] = [];
         const entries: CompletionEntry[] = [];
-        const uniques = createMap<string>();
+        const uniques = createMap<true>();
 
         typeChecker.getResolvedSignature(argumentInfo.invocation, candidates);
 
@@ -259,7 +259,7 @@ namespace ts.Completions {
         return undefined;
     }
 
-    function addStringLiteralCompletionsFromType(type: Type, result: Push<CompletionEntry>, typeChecker: TypeChecker, uniques = createMap<string>()): void {
+    function addStringLiteralCompletionsFromType(type: Type, result: Push<CompletionEntry>, typeChecker: TypeChecker, uniques = createMap<true>()): void {
         if (type && type.flags & TypeFlags.TypeParameter) {
             type = typeChecker.getBaseConstraintOfType(type);
         }
@@ -273,8 +273,8 @@ namespace ts.Completions {
         }
         else if (type.flags & TypeFlags.StringLiteral) {
             const name = (<LiteralType>type).text;
-            if (!uniques.get(name)) {
-                uniques.set(name, name);
+            if (!uniques.has(name)) {
+                uniques.set(name, true);
                 result.push({
                     name,
                     kindModifiers: ScriptElementKindModifier.none,