Don't crash in MSBuildWorkspace on malformed paths

src/Workspaces/Core/MSBuild/MSBuild/MSBuildProjectLoader.Worker.cs

@@ -408,10 +408,16 @@ private IEnumerable<AnalyzerReference> ResolveAnalyzerReferences(CommandLineArgu
 
                 foreach (var path in commandLineArgs.AnalyzerReferences.Select(r => r.FilePath))
                 {
-                    var fullPath = Path.GetFullPath(path);
-                    if (File.Exists(fullPath))
+                    string fullPath;
+
+                    if (PathUtilities.IsAbsolute(path))
                     {
-                        analyzerLoader.AddDependencyLocation(fullPath);
+                        fullPath = FileUtilities.TryNormalizeAbsolutePath(path);
+
+                        if (fullPath != null && File.Exists(fullPath))
+                        {
+                            analyzerLoader.AddDependencyLocation(fullPath);
+                        }
                     }
                 }
 

src/Workspaces/Core/MSBuild/MSBuild/PathResolver.cs

@@ -65,7 +65,7 @@ public bool TryGetAbsoluteProjectPath(string path, string baseDirectory, Diagnos
             return true;
         }
 
-        private string GetAbsolutePath(string path, string baseDirectory)
-            => Path.GetFullPath(FileUtilities.ResolveRelativePath(path, baseDirectory) ?? path);
+        private static string GetAbsolutePath(string path, string baseDirectory)
+            => FileUtilities.NormalizeAbsolutePath(FileUtilities.ResolveRelativePath(path, baseDirectory) ?? path);
     }
 }

src/Workspaces/Core/MSBuild/MSBuild/ProjectFile/CommandLineArgumentReader.cs

@@ -118,8 +118,9 @@ protected string GetDocumentFilePath(MSB.Framework.ITaskItem documentItem)
 
         protected string GetAbsolutePath(string path)
         {
-            var directoryPath = PathUtilities.GetDirectoryName(Project.FullPath);
-            return Path.GetFullPath(FileUtilities.ResolveRelativePath(path, directoryPath) ?? path);
+            var baseDirectory = PathUtilities.GetDirectoryName(Project.FullPath);
+            var absolutePath = FileUtilities.ResolveRelativePath(path, baseDirectory) ?? path;
+            return FileUtilities.TryNormalizeAbsolutePath(absolutePath) ?? absolutePath;
         }
 
         protected void ReadAdditionalFiles()

src/Workspaces/Core/MSBuild/MSBuild/ProjectFile/ProjectFile.cs

@@ -199,7 +199,7 @@ private string GetAbsolutePathRelativeToProject(string path)
         {
             // TODO (tomat): should we report an error when drive-relative path (e.g. "C:goo.cs") is encountered?
             var absolutePath = FileUtilities.ResolveRelativePath(path, _projectDirectory) ?? path;
-            return Path.GetFullPath(absolutePath);
+            return FileUtilities.TryNormalizeAbsolutePath(absolutePath) ?? absolutePath;
         }
 
         private string GetDocumentFilePath(MSB.Framework.ITaskItem documentItem)
@@ -234,27 +234,31 @@ protected static string GetDocumentLogicalPath(MSB.Framework.ITaskItem documentI
             }
             else
             {
-                var result = documentItem.ItemSpec;
-                if (Path.IsPathRooted(result))
+                var filePath = documentItem.ItemSpec;
+
+                if (!PathUtilities.IsAbsolute(filePath))
                 {
-                    // If we have an absolute path, there are two possibilities:
-                    result = Path.GetFullPath(result);
-
-                    // If the document is within the current project directory (or subdirectory), then the logical path is the relative path 
-                    // from the project's directory.
-                    if (result.StartsWith(projectDirectory, StringComparison.OrdinalIgnoreCase))
-                    {
-                        result = result.Substring(projectDirectory.Length);
-                    }
-                    else
-                    {
-                        // if the document lies outside the project's directory (or subdirectory) then place it logically at the root of the project.
-                        // if more than one document ends up with the same logical name then so be it (the workspace will survive.)
-                        return Path.GetFileName(result);
-                    }
+                    return filePath;
                 }
 
-                return result;
+                var normalizedPath = FileUtilities.TryNormalizeAbsolutePath(filePath);
+                if (normalizedPath == null)
+                {
+                    return filePath;
+                }
+
+                // If the document is within the current project directory (or subdirectory), then the logical path is the relative path 
+                // from the project's directory.
+                if (normalizedPath.StartsWith(projectDirectory, StringComparison.OrdinalIgnoreCase))
+                {
+                    return normalizedPath.Substring(projectDirectory.Length);
+                }
+                else
+                {
+                    // if the document lies outside the project's directory (or subdirectory) then place it logically at the root of the project.
+                    // if more than one document ends up with the same logical name then so be it (the workspace will survive.)
+                    return PathUtilities.GetFileName(normalizedPath);
+                }
             }
         }
 

src/Workspaces/MSBuildTest/MSBuildWorkspaceTests.cs

@@ -3597,6 +3597,8 @@ public async Task TestOpenProjectAsync_MalformedAdditionalFilePath()
 
                 // Project should open without an exception being thrown.
                 Assert.NotNull(project);
+
+                Assert.Contains(project.AdditionalDocuments, doc => doc.Name == "TEST::");
             }
         }