Fix relative path handling on Windows.

build_projects/dotnet-cli-build/MakeRelative.cs

@@ -17,21 +17,12 @@ public class MakeRelative : Task
         [Required]
         public string Path2 { get; set; }
 
-        public char SeparatorChar { get; set; }
-
         [Output]
         public ITaskItem RelativePath { get; set; }
 
         public override bool Execute()
         {
-            if (SeparatorChar == default(char))
-            {
-                SeparatorChar = Path.DirectorySeparatorChar;
-            }
-
-            var relativePath = GetRelativePath(Path1, Path2, SeparatorChar);
-
-            RelativePath = ToTaskItem(Path1, Path2, relativePath);
+            RelativePath = ToTaskItem(Path1, Path2, Path.GetRelativePath(Path1, Path2));
 
             return true;
         }
@@ -47,75 +38,5 @@ private static TaskItem ToTaskItem(string path1, string path2, string relativePa
 
             return framework;
         }
-
-        private static string GetRelativePath(string path1, string path2, char separator = default(char))
-        {
-
-            StringComparison compare;
-            if (CurrentPlatform.IsWindows)
-            {
-                compare = StringComparison.OrdinalIgnoreCase;
-                // check if paths are on the same volume
-                if (!string.Equals(Path.GetPathRoot(path1), Path.GetPathRoot(path2)))
-                {
-                    // on different volumes, "relative" path is just Path2
-                    return path2;
-                }
-            }
-            else
-            {
-                compare = StringComparison.Ordinal;
-            }
-
-            var index = 0;
-            var path1Segments = path1.Split(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
-            var path2Segments = path2.Split(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
-            // if path1 does not end with / it is assumed the end is not a directory
-            // we will assume that is isn't a directory by ignoring the last split
-            var len1 = path1Segments.Length - 1;
-            var len2 = path2Segments.Length;
-
-            // find largest common absolute path between both paths
-            var min = Math.Min(len1, len2);
-            while (min > index)
-            {
-                if (!string.Equals(path1Segments[index], path2Segments[index], compare))
-                {
-                    break;
-                }
-                // Handle scenarios where folder and file have same name (only if os supports same name for file and directory)
-                // e.g. /file/name /file/name/app
-                else if ((len1 == index && len2 > index + 1) || (len1 > index && len2 == index + 1))
-                {
-                    break;
-                }
-                ++index;
-            }
-
-            var path = "";
-
-            // check if path2 ends with a non-directory separator and if path1 has the same non-directory at the end
-            if (len1 + 1 == len2 && !string.IsNullOrEmpty(path1Segments[index]) &&
-                string.Equals(path1Segments[index], path2Segments[index], compare))
-            {
-                return path;
-            }
-
-            for (var i = index; len1 > i; ++i)
-            {
-                path += ".." + separator;
-            }
-            for (var i = index; len2 - 1 > i; ++i)
-            {
-                path += path2Segments[i] + separator;
-            }
-            // if path2 doesn't end with an empty string it means it ended with a non-directory name, so we add it back
-            if (!string.IsNullOrEmpty(path2Segments[len2 - 1]))
-            {
-                path += path2Segments[len2 - 1];
-            }
-
-            return path;
-        }
     }
 }

build_projects/dotnet-cli-build/dotnet-cli-build.csproj

@@ -14,6 +14,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.NETCore.App" Version="$(CLI_SharedFrameworkVersion)" />
     <PackageReference Include="Microsoft.Build" Version="$(CLI_MSBuild_Version)" />
     <PackageReference Include="Microsoft.CSharp" Version="4.0.1" />
     <PackageReference Include="System.Dynamic.Runtime" Version="4.0.11" />

src/Microsoft.DotNet.Cli.Utils/PathUtility.cs

@@ -151,7 +151,7 @@ public static string GetRelativePath(string path1, string path2, char separator,
             {
                 compare = StringComparison.OrdinalIgnoreCase;
                 // check if paths are on the same volume
-                if (!string.Equals(Path.GetPathRoot(path1), Path.GetPathRoot(path2)))
+                if (!string.Equals(Path.GetPathRoot(path1), Path.GetPathRoot(path2), compare))
                 {
                     // on different volumes, "relative" path is just path2
                     return path2;
@@ -273,7 +273,22 @@ public static string RemoveExtraPathSeparators(string path)
 
             foreach (var component in components)
             {
-                if (!string.IsNullOrEmpty(component))
+                if (string.IsNullOrEmpty(component))
+                {
+                    continue;
+                }
+
+                if (string.IsNullOrEmpty(result))
+                {
+                    result = component;
+
+                    // On Windows, manually append a separator for drive references because Path.Combine won't do so
+                    if (result.EndsWith(":") && RuntimeEnvironment.OperatingSystemPlatform == Platform.Windows)
+                    {
+                        result += Path.DirectorySeparatorChar;
+                    }
+                }
+                else
                 {
                     result = Path.Combine(result, component);
                 }

src/dotnet/MsbuildProject.cs

@@ -256,7 +256,7 @@ private IEnumerable<string> GetIncludeAlternativesForRemoval(string reference)
 
             string fullPath = Path.GetFullPath(reference);
             ret.Add(fullPath);
-            ret.Add(PathUtility.GetRelativePath(ProjectDirectory, fullPath));
+            ret.Add(Path.GetRelativePath(ProjectDirectory, fullPath));
 
             return ret;
         }

src/dotnet/SlnFileExtensions.cs

@@ -23,7 +23,7 @@ public static void AddProject(this SlnFile slnFile, string fullProjectPath)
                 throw new ArgumentException();
             }
 
-            var relativeProjectPath = PathUtility.GetRelativePath(
+            var relativeProjectPath = Path.GetRelativePath(
                 PathUtility.EnsureTrailingSlash(slnFile.BaseDirectory),
                 fullProjectPath);
 

src/dotnet/commands/dotnet-add/dotnet-add-reference/Program.cs

@@ -91,7 +91,7 @@ public override int Execute()
             }
 
             var relativePathReferences = _appliedCommand.Arguments.Select((r) =>
-                                                                              PathUtility.GetRelativePath(msbuildProj.ProjectDirectory, Path.GetFullPath(r)))
+                                                                              Path.GetRelativePath(msbuildProj.ProjectDirectory, Path.GetFullPath(r)))
                                                         .ToList();
 
             int numberOfAddedReferences = msbuildProj.AddProjectToProjectReferences(

src/dotnet/commands/dotnet-sln/remove/Program.cs

@@ -41,7 +41,7 @@ public override int Execute()
             SlnFile slnFile = SlnFileFactory.CreateFromFileOrDirectory(_fileOrDirectory);
 
             var relativeProjectPaths = _appliedCommand.Arguments.Select(p =>
-                                                                            PathUtility.GetRelativePath(
+                                                                            Path.GetRelativePath(
                                                                                 PathUtility.EnsureTrailingSlash(slnFile.BaseDirectory),
                                                                                 Path.GetFullPath(p)))
                                                       .ToList();

test/Microsoft.DotNet.Cli.Utils.Tests/PathUtilityTests.cs

@@ -0,0 +1,34 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Microsoft.DotNet.Tools.Common;
+using Microsoft.DotNet.Tools.Test.Utilities;
+using Xunit;
+
+namespace Microsoft.DotNet.Cli.Utils
+{
+    public class PathUtilityTests : TestBase
+    {
+        /// <summary>
+        /// Tests that PathUtility.GetRelativePath treats drive references as case insensitive on Windows.
+        /// </summary>
+        [WindowsOnlyFact]
+        public void GetRelativePathWithCaseInsensitiveDrives()
+        {
+            Assert.Equal(@"bar\", PathUtility.GetRelativePath(@"C:\foo\", @"C:\foo\bar\"));
+            Assert.Equal(@"Bar\Baz\", PathUtility.GetRelativePath(@"c:\foo\", @"C:\Foo\Bar\Baz\"));
+            Assert.Equal(@"baz\Qux\", PathUtility.GetRelativePath(@"C:\fOO\bar\", @"c:\foo\BAR\baz\Qux\"));
+            Assert.Equal(@"d:\foo\", PathUtility.GetRelativePath(@"C:\foo\", @"d:\foo\"));
+        }
+
+        /// <summary>
+        /// Tests that PathUtility.RemoveExtraPathSeparators works correctly with drive references on Windows.
+        /// </summary>
+        [WindowsOnlyFact]
+        public void RemoveExtraPathSeparatorsWithDrives()
+        {
+            Assert.Equal(@"c:\foo\bar\baz\", PathUtility.RemoveExtraPathSeparators(@"c:\\\foo\\\\bar\baz\\"));
+            Assert.Equal(@"D:\QUX\", PathUtility.RemoveExtraPathSeparators(@"D:\\\\\QUX\"));
+        }
+    }
+}