From c8aedbf382b615059b922ba8ec6593069ad94e27 Mon Sep 17 00:00:00 2001
From: Asad Saeeduddin <masaeedu@gmail.com>
Date: Sat, 20 Feb 2016 17:40:39 -0500
Subject: [PATCH] Address PR feedback: expand ternary return into if block, add
 check to ensure proper options usage

---
 src/compiler/program.ts   |  4 ++++
 src/compiler/utilities.ts | 10 ++++++----
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index d41f34df0b3..ef190df6a4f 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -1670,6 +1670,10 @@ namespace ts {
                 }
             }
 
+            if (!options.declaration && options.declarationDir) {
+                programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Option_0_cannot_be_specified_without_specifying_option_1, "declarationDir", "declaration"));
+            }
+
             const languageVersion = options.target || ScriptTarget.ES3;
             const outFile = options.outFile || options.out;
 
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 40b5462888e..9c598da9069 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -2015,11 +2015,13 @@ namespace ts {
     export function getDeclarationEmitOutputFilePath(sourceFile: SourceFile, host: EmitHost) {
         const options = host.getCompilerOptions();
         const outputDir = options.declarationDir || options.outDir; // Prefer declaration folder if specified
-        return options.declaration ? removeFileExtension(
-            outputDir
+
+        if (options.declaration) {
+            const path = outputDir
                 ? getSourceFilePathInNewDir(sourceFile, host, outputDir)
-                : sourceFile.fileName
-        ) + ".d.ts" : undefined;
+                : sourceFile.fileName;
+            return removeFileExtension(path) + ".d.ts";
+        }
     }
 
     export function getEmitScriptTarget(compilerOptions: CompilerOptions) {