From 85d589431c5469117a1f0caece44c48bbdefcf38 Mon Sep 17 00:00:00 2001
From: Torben Fitschen <torben.fitschen@mayflower.de>
Date: Fri, 9 Sep 2016 11:07:23 +0200
Subject: [PATCH 1/2] Added detection for case sensitive file systems

---
 src/compiler/sys.ts | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index 437cf8e05ec06..171f44391030f 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -311,9 +311,19 @@ namespace ts {
                 return parseInt(process.version.charAt(1)) >= 4;
             }
 
+            function isFileSystemCaseSensitive(): boolean {
+                // win32\win64 are case insensitive platforms
+                if (platform === "win32" || platform === "win64") {
+                    return false;
+                }
+
+                const upperCaseFilename = _path.basename(__filename).toUpperCase();
+
+                return !fileExists(_path.join(_path.dirname(__filename), upperCaseFilename));
+            }
+
             const platform: string = _os.platform();
-            // win32\win64 are case insensitive platforms, MacOS (darwin) by default is also case insensitive
-            const useCaseSensitiveFileNames = platform !== "win32" && platform !== "win64" && platform !== "darwin";
+            const useCaseSensitiveFileNames = isFileSystemCaseSensitive();
 
             function readFile(fileName: string, encoding?: string): string {
                 if (!fileExists(fileName)) {

From 5cdbe773c6a89075cceb966474b6d6dba6869cf8 Mon Sep 17 00:00:00 2001
From: Vladimir Matveev <vladima@microsoft.com>
Date: Mon, 3 Oct 2016 14:42:06 -0700
Subject: [PATCH 2/2] guard against cases when current file name is already in
 uppercase

---
 src/compiler/sys.ts | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index ed89b9d161138..2d4fcd241aa04 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -316,10 +316,9 @@ namespace ts {
                 if (platform === "win32" || platform === "win64") {
                     return false;
                 }
-
-                const upperCaseFilename = _path.basename(__filename).toUpperCase();
-
-                return !fileExists(_path.join(_path.dirname(__filename), upperCaseFilename));
+                // convert current file name to upper case / lower case and check if file exists
+                // (guards against cases when name is already all uppercase or lowercase)
+                return !fileExists(__filename.toUpperCase()) || !fileExists(__filename.toLowerCase());
             }
 
             const platform: string = _os.platform();