From bb615ac3f9ef30589f1afe8a4487de8938108660 Mon Sep 17 00:00:00 2001
From: Alexander T <alexander.v.tarasyuk@gmail.com>
Date: Fri, 11 May 2018 13:47:44 +0300
Subject: [PATCH 1/2] Add declarationDir to excludeSpec

---
 src/compiler/commandLineParser.ts | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index f648bddefe9a7..d9bfc93b78d65 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1607,10 +1607,13 @@ namespace ts {
                     createCompilerDiagnosticOnlyIfJson(Diagnostics.Compiler_option_0_requires_a_value_of_type_1, "exclude", "Array");
                 }
             }
-            else {
-                const outDir = raw.compilerOptions && raw.compilerOptions.outDir;
-                if (outDir) {
-                    excludeSpecs = [outDir];
+            else if (raw.compilerOptions) {
+                const outDir = raw.compilerOptions.outDir;
+                const declarationDir = raw.compilerOptions.declarationDir;
+                const excludeDirs = [outDir, declarationDir].filter(dir => dir);
+
+                if (excludeDirs.length) {
+                    excludeSpecs = excludeDirs;
                 }
             }
 

From 60d39d7f18d831706e2b067d5a8079cdd023291a Mon Sep 17 00:00:00 2001
From: Alexader <alexander.v.tarasyuk@gmail.com>
Date: Fri, 11 May 2018 21:27:40 +0300
Subject: [PATCH 2/2] add tests

---
 src/compiler/commandLineParser.ts        |  5 ++---
 src/harness/unittests/tsconfigParsing.ts | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index d9bfc93b78d65..8b963409ab6ad 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1610,10 +1610,9 @@ namespace ts {
             else if (raw.compilerOptions) {
                 const outDir = raw.compilerOptions.outDir;
                 const declarationDir = raw.compilerOptions.declarationDir;
-                const excludeDirs = [outDir, declarationDir].filter(dir => dir);
 
-                if (excludeDirs.length) {
-                    excludeSpecs = excludeDirs;
+                if (outDir || declarationDir) {
+                    excludeSpecs = [outDir, declarationDir].filter(d => !!d);
                 }
             }
 
diff --git a/src/harness/unittests/tsconfigParsing.ts b/src/harness/unittests/tsconfigParsing.ts
index f1b4d5265816b..7a47481b88d3f 100644
--- a/src/harness/unittests/tsconfigParsing.ts
+++ b/src/harness/unittests/tsconfigParsing.ts
@@ -217,6 +217,29 @@ namespace ts {
             assertParseFileList(tsconfigWithExclude, "tsconfig.json", rootDir, allFiles, allFiles);
         });
 
+        it("exclude declarationDir unless overridden", () => {
+            const tsconfigWithoutExclude =
+            `{
+                "compilerOptions": {
+                    "declarationDir": "declarations"
+                }
+            }`;
+            const tsconfigWithExclude =
+            `{
+                "compilerOptions": {
+                    "declarationDir": "declarations"
+                },
+                "exclude": [ "types" ]
+            }`;
+
+            const rootDir = "/";
+            const allFiles = ["/declarations/a.d.ts", "/a.ts"];
+            const expectedFiles = ["/a.ts"];
+
+            assertParseFileList(tsconfigWithoutExclude, "tsconfig.json", rootDir, allFiles, expectedFiles);
+            assertParseFileList(tsconfigWithExclude, "tsconfig.json", rootDir, allFiles, allFiles);
+        });
+
         it("implicitly exclude common package folders", () => {
             assertParseFileList(
                 `{}`,