From 6dcf3cf75696d79a7f422ab8a7f423bc36352aed Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Tue, 10 Nov 2015 12:06:25 -0800
Subject: [PATCH 01/11] Add case sensitivity-check, only error on failure when
 outDir is specified and resource based paths are found

---
 src/compiler/program.ts | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 8f031a4de43..aee66834a11 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -888,7 +888,7 @@ namespace ts {
 
         function computeCommonSourceDirectory(sourceFiles: SourceFile[]): string {
             let commonPathComponents: string[];
-            forEach(files, sourceFile => {
+            const failed = forEach(files, sourceFile => {
                 // Each file contributes into common source file path
                 if (isDeclarationFile(sourceFile)) {
                     return;
@@ -903,11 +903,12 @@ namespace ts {
                     return;
                 }
 
+                const caseSensitive = host.useCaseSensitiveFileNames();
                 for (let i = 0, n = Math.min(commonPathComponents.length, sourcePathComponents.length); i < n; i++) {
-                    if (commonPathComponents[i] !== sourcePathComponents[i]) {
+                    if (caseSensitive ? commonPathComponents[i] !== sourcePathComponents[i] : commonPathComponents[i].toLocaleLowerCase() !== sourcePathComponents[i].toLocaleLowerCase()) {
                         if (i === 0) {
-                            programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Cannot_find_the_common_subdirectory_path_for_the_input_files));
-                            return;
+                            // Failed to find any common path component
+                            return true;
                         }
 
                         // New common path found that is 0 -> i-1
@@ -922,6 +923,11 @@ namespace ts {
                 }
             });
 
+            // A common path can not be found when paths span multiple drives on windows, for example
+            if (failed) {
+                return "";
+            }
+
             if (!commonPathComponents) { // Can happen when all input files are .d.ts files
                 return currentDirectory;
             }
@@ -1045,6 +1051,10 @@ namespace ts {
                 else {
                     // Compute the commonSourceDirectory from the input files
                     commonSourceDirectory = computeCommonSourceDirectory(files);
+                    // If we failed to find a good common directory, but outDir is specified and at least one of our files is on a windows drive/URL/other resource, add a failure
+                    if (options.outDir && commonSourceDirectory === "" && forEach(files, file => getRootLength(file.fileName) > 1)) {
+                            programDiagnostics.add(createCompilerDiagnostic(Diagnostics.Cannot_find_the_common_subdirectory_path_for_the_input_files));
+                    }
                 }
 
                 if (commonSourceDirectory && commonSourceDirectory[commonSourceDirectory.length - 1] !== directorySeparator) {

From 97d170b388102bded0fdd68384c3a43b4f871fe6 Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Tue, 10 Nov 2015 13:10:44 -0800
Subject: [PATCH 02/11] Support to tests for absolute paths, add common src dir
 edgecase tests

---
 src/harness/compilerRunner.ts                 | 22 ++++++-------------
 tests/baselines/reference/commonSourceDir1.js | 13 +++++++++++
 .../reference/commonSourceDir1.symbols        |  8 +++++++
 .../reference/commonSourceDir1.types          |  8 +++++++
 .../reference/commonSourceDir2.errors.txt     |  9 ++++++++
 tests/baselines/reference/commonSourceDir2.js | 12 ++++++++++
 tests/baselines/reference/commonSourceDir3.js | 12 ++++++++++
 .../reference/commonSourceDir3.symbols        |  8 +++++++
 .../reference/commonSourceDir3.types          |  8 +++++++
 .../reference/commonSourceDir4.errors.txt     |  9 ++++++++
 tests/baselines/reference/commonSourceDir4.js | 12 ++++++++++
 tests/cases/compiler/commonSourceDir1.ts      |  6 +++++
 tests/cases/compiler/commonSourceDir2.ts      |  6 +++++
 tests/cases/compiler/commonSourceDir3.ts      |  6 +++++
 tests/cases/compiler/commonSourceDir4.ts      |  7 ++++++
 15 files changed, 131 insertions(+), 15 deletions(-)
 create mode 100644 tests/baselines/reference/commonSourceDir1.js
 create mode 100644 tests/baselines/reference/commonSourceDir1.symbols
 create mode 100644 tests/baselines/reference/commonSourceDir1.types
 create mode 100644 tests/baselines/reference/commonSourceDir2.errors.txt
 create mode 100644 tests/baselines/reference/commonSourceDir2.js
 create mode 100644 tests/baselines/reference/commonSourceDir3.js
 create mode 100644 tests/baselines/reference/commonSourceDir3.symbols
 create mode 100644 tests/baselines/reference/commonSourceDir3.types
 create mode 100644 tests/baselines/reference/commonSourceDir4.errors.txt
 create mode 100644 tests/baselines/reference/commonSourceDir4.js
 create mode 100644 tests/cases/compiler/commonSourceDir1.ts
 create mode 100644 tests/cases/compiler/commonSourceDir2.ts
 create mode 100644 tests/cases/compiler/commonSourceDir3.ts
 create mode 100644 tests/cases/compiler/commonSourceDir4.ts

diff --git a/src/harness/compilerRunner.ts b/src/harness/compilerRunner.ts
index 848f229f109..f7bb23527dd 100644
--- a/src/harness/compilerRunner.ts
+++ b/src/harness/compilerRunner.ts
@@ -45,14 +45,10 @@ class CompilerBaselineRunner extends RunnerBase {
             // Mocha holds onto the closure environment of the describe callback even after the test is done.
             // Everything declared here should be cleared out in the "after" callback.
             let justName: string;
-            let content: string;
-            let testCaseContent: { settings: Harness.TestCaseParser.CompilerSettings; testUnitData: Harness.TestCaseParser.TestUnitData[]; };
 
-            let units: Harness.TestCaseParser.TestUnitData[];
             let tcSettings: Harness.TestCaseParser.CompilerSettings;
 
             let lastUnit: Harness.TestCaseParser.TestUnitData;
-            let rootDir: string;
 
             let result: Harness.Compiler.CompilerResult;
             let program: ts.Program;
@@ -65,12 +61,12 @@ class CompilerBaselineRunner extends RunnerBase {
 
             before(() => {
                 justName = fileName.replace(/^.*[\\\/]/, ""); // strips the fileName from the path.
-                content = Harness.IO.readFile(fileName);
-                testCaseContent = Harness.TestCaseParser.makeUnitsFromTest(content, fileName);
-                units = testCaseContent.testUnitData;
+                const content = Harness.IO.readFile(fileName);
+                const testCaseContent = Harness.TestCaseParser.makeUnitsFromTest(content, fileName);
+                const units = testCaseContent.testUnitData;
                 tcSettings = testCaseContent.settings;
                 lastUnit = units[units.length - 1];
-                rootDir = lastUnit.originalFilePath.indexOf("conformance") === -1 ? "tests/cases/compiler/" : lastUnit.originalFilePath.substring(0, lastUnit.originalFilePath.lastIndexOf("/")) + "/";
+                const rootDir = lastUnit.originalFilePath.indexOf("conformance") === -1 ? "tests/cases/compiler/" : lastUnit.originalFilePath.substring(0, lastUnit.originalFilePath.lastIndexOf("/")) + "/";
                 harnessCompiler = Harness.Compiler.getCompiler();
                 // We need to assemble the list of input files for the compiler and other related files on the 'filesystem' (ie in a multi-file test)
                 // If the last file in a test uses require or a triple slash reference we'll assume all other files will be brought in via references,
@@ -78,16 +74,16 @@ class CompilerBaselineRunner extends RunnerBase {
                 toBeCompiled = [];
                 otherFiles = [];
                 if (/require\(/.test(lastUnit.content) || /reference\spath/.test(lastUnit.content)) {
-                    toBeCompiled.push({ unitName: rootDir + lastUnit.name, content: lastUnit.content });
+                    toBeCompiled.push({ unitName: ts.isRootedDiskPath(lastUnit.name) ? lastUnit.name : rootDir + lastUnit.name, content: lastUnit.content });
                     units.forEach(unit => {
                         if (unit.name !== lastUnit.name) {
-                            otherFiles.push({ unitName: rootDir + unit.name, content: unit.content });
+                            otherFiles.push({ unitName: ts.isRootedDiskPath(unit.name) ? unit.name : rootDir + unit.name, content: unit.content });
                         }
                     });
                 }
                 else {
                     toBeCompiled = units.map(unit => {
-                        return { unitName: rootDir + unit.name, content: unit.content };
+                        return { unitName: ts.isRootedDiskPath(unit.name) ? unit.name : rootDir + unit.name, content: unit.content };
                     });
                 }
 
@@ -104,12 +100,8 @@ class CompilerBaselineRunner extends RunnerBase {
                 // Mocha holds onto the closure environment of the describe callback even after the test is done.
                 // Therefore we have to clean out large objects after the test is done.
                 justName = undefined;
-                content = undefined;
-                testCaseContent = undefined;
-                units = undefined;
                 tcSettings = undefined;
                 lastUnit = undefined;
-                rootDir = undefined;
                 result = undefined;
                 program = undefined;
                 options = undefined;
diff --git a/tests/baselines/reference/commonSourceDir1.js b/tests/baselines/reference/commonSourceDir1.js
new file mode 100644
index 00000000000..68833aed49d
--- /dev/null
+++ b/tests/baselines/reference/commonSourceDir1.js
@@ -0,0 +1,13 @@
+//// [tests/cases/compiler/commonSourceDir1.ts] ////
+
+//// [bar.ts]
+var x: number;
+
+//// [baz.ts]
+var y: number;
+
+
+//// [bar.js]
+var x;
+//// [baz.js]
+var y;
diff --git a/tests/baselines/reference/commonSourceDir1.symbols b/tests/baselines/reference/commonSourceDir1.symbols
new file mode 100644
index 00000000000..9248e0c97af
--- /dev/null
+++ b/tests/baselines/reference/commonSourceDir1.symbols
@@ -0,0 +1,8 @@
+=== A:/foo/bar.ts ===
+var x: number;
+>x : Symbol(x, Decl(bar.ts, 0, 3))
+
+=== A:/foo/baz.ts ===
+var y: number;
+>y : Symbol(y, Decl(baz.ts, 0, 3))
+
diff --git a/tests/baselines/reference/commonSourceDir1.types b/tests/baselines/reference/commonSourceDir1.types
new file mode 100644
index 00000000000..6c9864c02cc
--- /dev/null
+++ b/tests/baselines/reference/commonSourceDir1.types
@@ -0,0 +1,8 @@
+=== A:/foo/bar.ts ===
+var x: number;
+>x : number
+
+=== A:/foo/baz.ts ===
+var y: number;
+>y : number
+
diff --git a/tests/baselines/reference/commonSourceDir2.errors.txt b/tests/baselines/reference/commonSourceDir2.errors.txt
new file mode 100644
index 00000000000..85bcf5d9c72
--- /dev/null
+++ b/tests/baselines/reference/commonSourceDir2.errors.txt
@@ -0,0 +1,9 @@
+error TS5009: Cannot find the common subdirectory path for the input files.
+
+
+!!! error TS5009: Cannot find the common subdirectory path for the input files.
+==== A:/foo/bar.ts (0 errors) ====
+    var x: number;
+    
+==== B:/foo/baz.ts (0 errors) ====
+    var y: number;
\ No newline at end of file
diff --git a/tests/baselines/reference/commonSourceDir2.js b/tests/baselines/reference/commonSourceDir2.js
new file mode 100644
index 00000000000..cf263b51fb6
--- /dev/null
+++ b/tests/baselines/reference/commonSourceDir2.js
@@ -0,0 +1,12 @@
+//// [tests/cases/compiler/commonSourceDir2.ts] ////
+
+//// [bar.ts]
+var x: number;
+
+//// [baz.ts]
+var y: number;
+
+//// [bar.js]
+var x;
+//// [baz.js]
+var y;
diff --git a/tests/baselines/reference/commonSourceDir3.js b/tests/baselines/reference/commonSourceDir3.js
new file mode 100644
index 00000000000..0535d51f4bf
--- /dev/null
+++ b/tests/baselines/reference/commonSourceDir3.js
@@ -0,0 +1,12 @@
+//// [tests/cases/compiler/commonSourceDir3.ts] ////
+
+//// [bar.ts]
+var x: number;
+
+//// [baz.ts]
+var y: number;
+
+//// [bar.js]
+var x;
+//// [baz.js]
+var y;
diff --git a/tests/baselines/reference/commonSourceDir3.symbols b/tests/baselines/reference/commonSourceDir3.symbols
new file mode 100644
index 00000000000..b8783523dfd
--- /dev/null
+++ b/tests/baselines/reference/commonSourceDir3.symbols
@@ -0,0 +1,8 @@
+=== A:/foo/bar.ts ===
+var x: number;
+>x : Symbol(x, Decl(bar.ts, 0, 3))
+
+=== a:/foo/baz.ts ===
+var y: number;
+>y : Symbol(y, Decl(baz.ts, 0, 3))
+
diff --git a/tests/baselines/reference/commonSourceDir3.types b/tests/baselines/reference/commonSourceDir3.types
new file mode 100644
index 00000000000..a0b95275897
--- /dev/null
+++ b/tests/baselines/reference/commonSourceDir3.types
@@ -0,0 +1,8 @@
+=== A:/foo/bar.ts ===
+var x: number;
+>x : number
+
+=== a:/foo/baz.ts ===
+var y: number;
+>y : number
+
diff --git a/tests/baselines/reference/commonSourceDir4.errors.txt b/tests/baselines/reference/commonSourceDir4.errors.txt
new file mode 100644
index 00000000000..f3493504e4d
--- /dev/null
+++ b/tests/baselines/reference/commonSourceDir4.errors.txt
@@ -0,0 +1,9 @@
+error TS5009: Cannot find the common subdirectory path for the input files.
+
+
+!!! error TS5009: Cannot find the common subdirectory path for the input files.
+==== A:/foo/bar.ts (0 errors) ====
+    var x: number;
+    
+==== a:/foo/baz.ts (0 errors) ====
+    var y: number;
\ No newline at end of file
diff --git a/tests/baselines/reference/commonSourceDir4.js b/tests/baselines/reference/commonSourceDir4.js
new file mode 100644
index 00000000000..2f2af9f68b2
--- /dev/null
+++ b/tests/baselines/reference/commonSourceDir4.js
@@ -0,0 +1,12 @@
+//// [tests/cases/compiler/commonSourceDir4.ts] ////
+
+//// [bar.ts]
+var x: number;
+
+//// [baz.ts]
+var y: number;
+
+//// [bar.js]
+var x;
+//// [baz.js]
+var y;
diff --git a/tests/cases/compiler/commonSourceDir1.ts b/tests/cases/compiler/commonSourceDir1.ts
new file mode 100644
index 00000000000..1a178ac0226
--- /dev/null
+++ b/tests/cases/compiler/commonSourceDir1.ts
@@ -0,0 +1,6 @@
+// @outDir: A:/
+// @Filename: A:/foo/bar.ts
+var x: number;
+
+// @Filename: A:/foo/baz.ts
+var y: number;
diff --git a/tests/cases/compiler/commonSourceDir2.ts b/tests/cases/compiler/commonSourceDir2.ts
new file mode 100644
index 00000000000..68dab0727a3
--- /dev/null
+++ b/tests/cases/compiler/commonSourceDir2.ts
@@ -0,0 +1,6 @@
+// @outDir: A:/
+// @Filename: A:/foo/bar.ts
+var x: number;
+
+// @Filename: B:/foo/baz.ts
+var y: number;
\ No newline at end of file
diff --git a/tests/cases/compiler/commonSourceDir3.ts b/tests/cases/compiler/commonSourceDir3.ts
new file mode 100644
index 00000000000..cc42eb8f267
--- /dev/null
+++ b/tests/cases/compiler/commonSourceDir3.ts
@@ -0,0 +1,6 @@
+// @outDir: A:/
+// @Filename: A:/foo/bar.ts
+var x: number;
+
+// @Filename: a:/foo/baz.ts
+var y: number;
\ No newline at end of file
diff --git a/tests/cases/compiler/commonSourceDir4.ts b/tests/cases/compiler/commonSourceDir4.ts
new file mode 100644
index 00000000000..41ee7a0344a
--- /dev/null
+++ b/tests/cases/compiler/commonSourceDir4.ts
@@ -0,0 +1,7 @@
+// @useCaseSensitiveFileNames: true
+// @outDir: A:/
+// @Filename: A:/foo/bar.ts
+var x: number;
+
+// @Filename: a:/foo/baz.ts
+var y: number;
\ No newline at end of file

From a1cf51faacf18f4a3f91530688ec2c77fefd698d Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Tue, 10 Nov 2015 13:25:09 -0800
Subject: [PATCH 03/11] use canonical filename function

---
 src/compiler/program.ts | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index aee66834a11..03305dd368d 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -894,7 +894,7 @@ namespace ts {
                     return;
                 }
 
-                const sourcePathComponents = getNormalizedPathComponents(sourceFile.fileName, currentDirectory);
+                const sourcePathComponents = getNormalizedPathComponents(getCanonicalFileName(sourceFile.fileName), currentDirectory);
                 sourcePathComponents.pop(); // The base file name is not part of the common directory path
 
                 if (!commonPathComponents) {
@@ -903,9 +903,8 @@ namespace ts {
                     return;
                 }
 
-                const caseSensitive = host.useCaseSensitiveFileNames();
                 for (let i = 0, n = Math.min(commonPathComponents.length, sourcePathComponents.length); i < n; i++) {
-                    if (caseSensitive ? commonPathComponents[i] !== sourcePathComponents[i] : commonPathComponents[i].toLocaleLowerCase() !== sourcePathComponents[i].toLocaleLowerCase()) {
+                    if (commonPathComponents[i] !== sourcePathComponents[i]) {
                         if (i === 0) {
                             // Failed to find any common path component
                             return true;

From ebd7d2d93e914819f1b15b4e7e75d7da3905adad Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Tue, 10 Nov 2015 16:48:08 -0800
Subject: [PATCH 04/11] extract method

---
 src/harness/compilerRunner.ts | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/harness/compilerRunner.ts b/src/harness/compilerRunner.ts
index f7bb23527dd..4a599e96812 100644
--- a/src/harness/compilerRunner.ts
+++ b/src/harness/compilerRunner.ts
@@ -40,6 +40,10 @@ class CompilerBaselineRunner extends RunnerBase {
         this.basePath += "/" + this.testSuiteName;
     }
 
+    private makeUnitName(name: string, root: string) {
+        return ts.isRootedDiskPath(name) ? name : (root + name);
+    };
+            
     public checkTestCodeOutput(fileName: string) {
         describe("compiler tests for " + fileName, () => {
             // Mocha holds onto the closure environment of the describe callback even after the test is done.
@@ -74,16 +78,16 @@ class CompilerBaselineRunner extends RunnerBase {
                 toBeCompiled = [];
                 otherFiles = [];
                 if (/require\(/.test(lastUnit.content) || /reference\spath/.test(lastUnit.content)) {
-                    toBeCompiled.push({ unitName: ts.isRootedDiskPath(lastUnit.name) ? lastUnit.name : rootDir + lastUnit.name, content: lastUnit.content });
+                    toBeCompiled.push({ unitName: this.makeUnitName(lastUnit.name, rootDir), content: lastUnit.content });
                     units.forEach(unit => {
                         if (unit.name !== lastUnit.name) {
-                            otherFiles.push({ unitName: ts.isRootedDiskPath(unit.name) ? unit.name : rootDir + unit.name, content: unit.content });
+                            otherFiles.push({ unitName: this.makeUnitName(unit.name, rootDir), content: unit.content });
                         }
                     });
                 }
                 else {
                     toBeCompiled = units.map(unit => {
-                        return { unitName: ts.isRootedDiskPath(unit.name) ? unit.name : rootDir + unit.name, content: unit.content };
+                        return { unitName: this.makeUnitName(unit.name, rootDir), content: unit.content };
                     });
                 }
 

From 5ea25ba9a09f5a9860b92093012a3cedd32bf664 Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Wed, 11 Nov 2015 10:57:32 -0800
Subject: [PATCH 05/11] remove whitespace

---
 src/harness/compilerRunner.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/harness/compilerRunner.ts b/src/harness/compilerRunner.ts
index 4a599e96812..011b10e4e6b 100644
--- a/src/harness/compilerRunner.ts
+++ b/src/harness/compilerRunner.ts
@@ -43,7 +43,7 @@ class CompilerBaselineRunner extends RunnerBase {
     private makeUnitName(name: string, root: string) {
         return ts.isRootedDiskPath(name) ? name : (root + name);
     };
-            
+
     public checkTestCodeOutput(fileName: string) {
         describe("compiler tests for " + fileName, () => {
             // Mocha holds onto the closure environment of the describe callback even after the test is done.

From b24f8f35b762e6239454f4ab7431c2ab57086e43 Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Thu, 12 Nov 2015 14:09:51 -0800
Subject: [PATCH 06/11] go go go

---
 tests/cases/compiler/commonSourceDir3.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/cases/compiler/commonSourceDir3.ts b/tests/cases/compiler/commonSourceDir3.ts
index cc42eb8f267..54b6e8c89b7 100644
--- a/tests/cases/compiler/commonSourceDir3.ts
+++ b/tests/cases/compiler/commonSourceDir3.ts
@@ -1,3 +1,4 @@
+// @useCaseSensitiveFileNames: false
 // @outDir: A:/
 // @Filename: A:/foo/bar.ts
 var x: number;

From 5bcf8611210e5e988bb6317def16389a71b2074c Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Thu, 12 Nov 2015 15:58:11 -0800
Subject: [PATCH 07/11] use relative path from current directory

---
 src/compiler/program.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 3981d5a2421..28c51ce2f3a 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -947,7 +947,9 @@ namespace ts {
                 return currentDirectory;
             }
 
-            return getNormalizedPathFromPathComponents(commonPathComponents);
+            const path = getNormalizedPathFromPathComponents(commonPathComponents);
+            const relativePath = convertToRelativePath(path, currentDirectory, getCanonicalFileName);
+            return relativePath;
         }
 
         function checkSourceFilesBelongToPath(sourceFiles: SourceFile[], rootDirectory: string): boolean {

From ecd4435986be2e0e2ff9492ca524a2af7f2ebf02 Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Thu, 12 Nov 2015 16:22:35 -0800
Subject: [PATCH 08/11] Go all the way back to the original solution

---
 src/compiler/program.ts | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 3fb432d9668..1f0096e7f6e 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -910,7 +910,7 @@ namespace ts {
                     return;
                 }
 
-                const sourcePathComponents = getNormalizedPathComponents(getCanonicalFileName(sourceFile.fileName), currentDirectory);
+                const sourcePathComponents = getNormalizedPathComponents(sourceFile.fileName, currentDirectory);
                 sourcePathComponents.pop(); // The base file name is not part of the common directory path
 
                 if (!commonPathComponents) {
@@ -919,8 +919,9 @@ namespace ts {
                     return;
                 }
 
+                const caseSensitive = host.useCaseSensitiveFileNames();
                 for (let i = 0, n = Math.min(commonPathComponents.length, sourcePathComponents.length); i < n; i++) {
-                    if (commonPathComponents[i] !== sourcePathComponents[i]) {
+                    if (caseSensitive ? commonPathComponents[i] !== sourcePathComponents[i] : commonPathComponents[i].toLocaleLowerCase() !== sourcePathComponents[i].toLocaleLowerCase()) {
                         if (i === 0) {
                             // Failed to find any common path component
                             return true;
@@ -947,9 +948,7 @@ namespace ts {
                 return currentDirectory;
             }
 
-            const path = getNormalizedPathFromPathComponents(commonPathComponents);
-            const relativePath = convertToRelativePath(path, currentDirectory, getCanonicalFileName);
-            return relativePath;
+            return getNormalizedPathFromPathComponents(commonPathComponents);
         }
 
         function checkSourceFilesBelongToPath(sourceFiles: SourceFile[], rootDirectory: string): boolean {

From ff95731507bcf831f7339d25f72c37cc6c12fdd4 Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Fri, 13 Nov 2015 16:49:16 -0800
Subject: [PATCH 09/11] :S

---
 src/harness/compilerRunner.ts | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/src/harness/compilerRunner.ts b/src/harness/compilerRunner.ts
index 0785faccdf2..16616505c4e 100644
--- a/src/harness/compilerRunner.ts
+++ b/src/harness/compilerRunner.ts
@@ -50,9 +50,8 @@ class CompilerBaselineRunner extends RunnerBase {
             // Everything declared here should be cleared out in the "after" callback.
             let justName: string;
 
-            let tcSettings: Harness.TestCaseParser.CompilerSettings;
-
             let lastUnit: Harness.TestCaseParser.TestUnitData;
+            let tcSettings: Harness.TestCaseParser.CompilerSettings;
 
             let result: Harness.Compiler.CompilerResult;
             let program: ts.Program;
@@ -67,7 +66,7 @@ class CompilerBaselineRunner extends RunnerBase {
                 const content = Harness.IO.readFile(fileName);
                 const testCaseContent = Harness.TestCaseParser.makeUnitsFromTest(content, fileName);
                 const units = testCaseContent.testUnitData;
-                harnessSettings = testCaseContent.settings;
+                const tcSettings = testCaseContent.settings;
                 lastUnit = units[units.length - 1];
                 const rootDir = lastUnit.originalFilePath.indexOf("conformance") === -1 ? "tests/cases/compiler/" : lastUnit.originalFilePath.substring(0, lastUnit.originalFilePath.lastIndexOf("/")) + "/";
                 // We need to assemble the list of input files for the compiler and other related files on the 'filesystem' (ie in a multi-file test)
@@ -90,7 +89,7 @@ class CompilerBaselineRunner extends RunnerBase {
                 }
 
                 const output = Harness.Compiler.HarnessCompiler.compileFiles(
-                    toBeCompiled, otherFiles, harnessSettings, /* options */ undefined, /* currentDirectory */ undefined);
+                    toBeCompiled, otherFiles, tcSettings, /* options */ undefined, /* currentDirectory */ undefined);
 
                 options = output.options;
                 result = output.result;
@@ -101,7 +100,6 @@ class CompilerBaselineRunner extends RunnerBase {
                 // Mocha holds onto the closure environment of the describe callback even after the test is done.
                 // Therefore we have to clean out large objects after the test is done.
                 justName = undefined;
-                harnessSettings = undefined;
                 lastUnit = undefined;
                 result = undefined;
                 program = undefined;
@@ -178,7 +176,7 @@ class CompilerBaselineRunner extends RunnerBase {
 
                         const declFileCompilationResult =
                             Harness.Compiler.HarnessCompiler.compileDeclarationFiles(
-                                toBeCompiled, otherFiles, result, harnessSettings, options, /* currentDirectory */ undefined);
+                                toBeCompiled, otherFiles, result, tcSettings, options, /* currentDirectory */ undefined);
 
                         if (declFileCompilationResult && declFileCompilationResult.declResult.errors.length) {
                             jsCode += "\r\n\r\n//// [DtsFileErrors]\r\n";

From bfdb2d0fc98a2966b3564dde62860f93d87f0dac Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Fri, 13 Nov 2015 16:57:17 -0800
Subject: [PATCH 10/11] and somehow all that caused was a lint error

---
 src/harness/compilerRunner.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/harness/compilerRunner.ts b/src/harness/compilerRunner.ts
index 16616505c4e..dbe22beabcf 100644
--- a/src/harness/compilerRunner.ts
+++ b/src/harness/compilerRunner.ts
@@ -66,7 +66,7 @@ class CompilerBaselineRunner extends RunnerBase {
                 const content = Harness.IO.readFile(fileName);
                 const testCaseContent = Harness.TestCaseParser.makeUnitsFromTest(content, fileName);
                 const units = testCaseContent.testUnitData;
-                const tcSettings = testCaseContent.settings;
+                tcSettings = testCaseContent.settings;
                 lastUnit = units[units.length - 1];
                 const rootDir = lastUnit.originalFilePath.indexOf("conformance") === -1 ? "tests/cases/compiler/" : lastUnit.originalFilePath.substring(0, lastUnit.originalFilePath.lastIndexOf("/")) + "/";
                 // We need to assemble the list of input files for the compiler and other related files on the 'filesystem' (ie in a multi-file test)

From a989595044bf942cef77360e7225622f464e4a6b Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Tue, 17 Nov 2015 11:24:17 -0800
Subject: [PATCH 11/11] use getCanonicalFileName on path fragments as in other
 utility methods

---
 src/compiler/program.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 80f793cb50f..dc31dfb5213 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -919,9 +919,8 @@ namespace ts {
                     return;
                 }
 
-                const caseSensitive = host.useCaseSensitiveFileNames();
                 for (let i = 0, n = Math.min(commonPathComponents.length, sourcePathComponents.length); i < n; i++) {
-                    if (caseSensitive ? commonPathComponents[i] !== sourcePathComponents[i] : commonPathComponents[i].toLocaleLowerCase() !== sourcePathComponents[i].toLocaleLowerCase()) {
+                    if (getCanonicalFileName(commonPathComponents[i]) !== getCanonicalFileName(sourcePathComponents[i])) {
                         if (i === 0) {
                             // Failed to find any common path component
                             return true;