From 6e74f7ee11ae47fb2481dd07b998bc523aec75a5 Mon Sep 17 00:00:00 2001
From: Ryan Cavanaugh <RyanCavanaugh@users.noreply.github.com>
Date: Wed, 6 Dec 2017 15:58:50 -0800
Subject: [PATCH] Fix #20523

---
 src/services/codefixes/inferFromUsage.ts               | 5 +++++
 tests/cases/fourslash/incompleteFunctionCallCodefix.ts | 9 +++++++++
 2 files changed, 14 insertions(+)
 create mode 100644 tests/cases/fourslash/incompleteFunctionCallCodefix.ts

diff --git a/src/services/codefixes/inferFromUsage.ts b/src/services/codefixes/inferFromUsage.ts
index 9782619d41d..d7bfd1b621f 100644
--- a/src/services/codefixes/inferFromUsage.ts
+++ b/src/services/codefixes/inferFromUsage.ts
@@ -148,6 +148,11 @@ namespace ts.codefix {
             containingFunction.parameters.map(p => isIdentifier(p.name) ? inferTypeForVariableFromUsage(p.name, sourceFile, program, cancellationToken) : undefined);
         if (!types) return undefined;
 
+        // We didn't actually find a set of type inference positions matching each parameter position
+        if (containingFunction.parameters.length !== types.length) {
+            return undefined;
+        }
+        
         const textChanges = arrayFrom(mapDefinedIterator(zipToIterator(containingFunction.parameters, types), ([parameter, type]) =>
             type && !parameter.type && !parameter.initializer ? makeChange(containingFunction, parameter.end, type, program) : undefined));
         return textChanges.length ? { declaration: parameterDeclaration, textChanges } : undefined;
diff --git a/tests/cases/fourslash/incompleteFunctionCallCodefix.ts b/tests/cases/fourslash/incompleteFunctionCallCodefix.ts
new file mode 100644
index 00000000000..007eaa20f7f
--- /dev/null
+++ b/tests/cases/fourslash/incompleteFunctionCallCodefix.ts
@@ -0,0 +1,9 @@
+/// <reference path='fourslash.ts' />
+
+// @noImplicitAny: true
+//// function f(/*1*/x) {
+//// }
+//// f(
+
+verify.not.codeFixAvailable([]);
+