Add generation of the /editorconfig switch to the build tasks

src/Compilers/Core/MSBuildTask/ManagedCompiler.cs

@@ -133,6 +133,12 @@ public bool PublicSign
             get { return _store.GetOrDefault(nameof(PublicSign), false); }
         }
 
+        public ITaskItem[] EditorConfigFiles
+        {
+            set { _store[nameof(EditorConfigFiles)] = value; }
+            get { return (ITaskItem[])_store[nameof(EditorConfigFiles)]; }
+        }
+
         public bool EmitDebugInformation
         {
             set { _store[nameof(EmitDebugInformation)] = value; }
@@ -736,6 +742,7 @@ internal void AddResponseFileCommandsForSwitchesSinceInitialReleaseThatAreNeeded
 
             AddFeatures(commandLine, Features);
             AddEmbeddedFilesToCommandLine(commandLine);
+            AddEditorConfigFilesToCommandLine(commandLine);
         }
 
         /// <summary>
@@ -800,6 +807,20 @@ private void AddEmbeddedFilesToCommandLine(CommandLineBuilderExtension commandLi
             }
         }
 
+        /// <summary>
+        /// Adds a "/editorconfig:" switch to the command line for each .editorconfig file.
+        /// </summary>
+        private void AddEditorConfigFilesToCommandLine(CommandLineBuilderExtension commandLine)
+        {
+            if (EditorConfigFiles != null)
+            {
+                foreach (ITaskItem editorConfigFile in EditorConfigFiles)
+                {
+                    commandLine.AppendSwitchIfNotNull("/editorconfig:", editorConfigFile.ItemSpec);
+                }
+            }
+        }
+
         /// <summary>
         /// Configure the debug switches which will be placed on the compiler command-line.
         /// The matrix of debug type and symbol inputs and the desired results is as follows:

src/Compilers/Core/MSBuildTaskTests/CscTests.cs

@@ -286,5 +286,19 @@ public void Embed()
             csc.EmbeddedFiles = MSBuildUtil.CreateTaskItems();
             Assert.Equal(@"/debug:portable /out:test.exe test.cs", csc.GenerateResponseFileContents());
         }
+
+        [Fact]
+        public void EditorConfig()
+        {
+            var csc = new Csc();
+            csc.Sources = MSBuildUtil.CreateTaskItems("test.cs");
+            csc.EditorConfigFiles = MSBuildUtil.CreateTaskItems(".editorconfig");
+            Assert.Equal(@"/out:test.exe /editorconfig:.editorconfig test.cs", csc.GenerateResponseFileContents());
+
+            csc = new Csc();
+            csc.Sources = MSBuildUtil.CreateTaskItems("test.cs", "subdir\\test.cs");
+            csc.EditorConfigFiles = MSBuildUtil.CreateTaskItems(".editorconfig", "subdir\\.editorconfig");
+            Assert.Equal(@"/out:test.exe /editorconfig:.editorconfig /editorconfig:subdir\.editorconfig test.cs subdir\test.cs", csc.GenerateResponseFileContents());
+        }
     }
 }

src/Compilers/Core/MSBuildTaskTests/VbcTests.cs

@@ -283,5 +283,19 @@ public void Embed()
             vbc.EmbeddedFiles = MSBuildUtil.CreateTaskItems();
             Assert.Equal(@"/optionstrict:custom /debug:portable /out:test.exe test.vb", vbc.GenerateResponseFileContents());
         }
+
+        [Fact]
+        public void EditorConfig()
+        {
+            var vbc = new Vbc();
+            vbc.Sources = MSBuildUtil.CreateTaskItems("test.vb");
+            vbc.EditorConfigFiles = MSBuildUtil.CreateTaskItems(".editorconfig");
+            Assert.Equal(@"/optionstrict:custom /out:test.exe /editorconfig:.editorconfig test.vb", vbc.GenerateResponseFileContents());
+
+            vbc = new Vbc();
+            vbc.Sources = MSBuildUtil.CreateTaskItems("test.vb", "subdir\\test.vb");
+            vbc.EditorConfigFiles = MSBuildUtil.CreateTaskItems(".editorconfig", "subdir\\.editorconfig");
+            Assert.Equal(@"/optionstrict:custom /out:test.exe /editorconfig:.editorconfig /editorconfig:subdir\.editorconfig test.vb subdir\test.vb", vbc.GenerateResponseFileContents());
+        }
     }
 }