Merge pull request #5583 from DustinCampbell/issue-2638

Fix indentation when pressing ENTER in a partially completed from clause of a query expression

src/EditorFeatures/CSharpTest/Formatting/Indentation/SmartIndenterTests.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System.Linq;
-using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
-using Microsoft.CodeAnalysis.Editor.UnitTests;
 using Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces;
 using Microsoft.CodeAnalysis.Formatting.Rules;
-using Microsoft.CodeAnalysis.Text;
 using Microsoft.VisualStudio.Text;
 using Roslyn.Test.Utilities;
 using Xunit;
@@ -2531,6 +2528,29 @@ class UserViewModel
                 expectedIndentation: 25);
         }
 
+        [WorkItem(5495, "https://github.com/dotnet/roslyn/issues/5495")]
+        [Fact, Trait(Traits.Feature, Traits.Features.SmartIndent)]
+        public void AfterPartialFromClause()
+        {
+            var code = @"
+using System.Linq;
+
+class C
+{
+    void M()
+    {
+        var q = from x
+
+    }
+}
+";
+
+            AssertSmartIndent(
+                code,
+                indentationLine: 8,
+                expectedIndentation: 16);
+        }
+
         private static void AssertSmartIndentInProjection(string markup, int expectedIndentation, CSharpParseOptions options = null)
         {
             var optionsSet = options != null

src/Workspaces/CSharp/Portable/Formatting/Rules/QueryExpressionFormattingRule.cs

@@ -26,6 +26,36 @@ public override void AddSuppressOperations(List<SuppressOperation> list, SyntaxN
             }
         }
 
+        private void AddIndentBlockOperationsForFromClause(List<IndentBlockOperation> list, FromClauseSyntax fromClause)
+        {
+            // Only add the indent block operation if the 'in' keyword is present. Otherwise, we'll get the following:
+            //
+            //     from x
+            //         in args
+            //
+            // Rather than:
+            //
+            //     from x
+            //     in args
+            //
+            // However, we want to get the following result if the 'in' keyword is present to allow nested queries
+            // to be formatted properly.
+            //
+            //     from x in
+            //         args
+
+            if (fromClause.InKeyword.IsMissing)
+            {
+                return;
+            }
+
+            var baseToken = fromClause.FromKeyword;
+            var startToken = fromClause.Expression.GetFirstToken(includeZeroWidth: true);
+            var endToken = fromClause.Expression.GetLastToken(includeZeroWidth: true);
+
+            AddIndentBlockOperation(list, baseToken, startToken, endToken);
+        }
+
         public override void AddIndentBlockOperations(List<IndentBlockOperation> list, SyntaxNode node, OptionSet optionSet, NextAction<IndentBlockOperation> nextOperation)
         {
             nextOperation.Invoke(list);
@@ -33,19 +63,15 @@ public override void AddIndentBlockOperations(List<IndentBlockOperation> list, S
             var queryExpression = node as QueryExpressionSyntax;
             if (queryExpression != null)
             {
-                var firstToken = queryExpression.FromClause.Expression.GetFirstToken(includeZeroWidth: true);
-                var lastToken = queryExpression.FromClause.Expression.GetLastToken(includeZeroWidth: true);
-                AddIndentBlockOperation(list, queryExpression.FromClause.FromKeyword, firstToken, lastToken);
+                AddIndentBlockOperationsForFromClause(list, queryExpression.FromClause);
 
-                for (int i = 0; i < queryExpression.Body.Clauses.Count; i++)
+                foreach (var queryClause in queryExpression.Body.Clauses)
                 {
                     // if it is nested query expression
-                    var fromClause = queryExpression.Body.Clauses[i] as FromClauseSyntax;
+                    var fromClause = queryClause as FromClauseSyntax;
                     if (fromClause != null)
                     {
-                        firstToken = fromClause.Expression.GetFirstToken(includeZeroWidth: true);
-                        lastToken = fromClause.Expression.GetLastToken(includeZeroWidth: true);
-                        AddIndentBlockOperation(list, fromClause.FromKeyword, firstToken, lastToken);
+                        AddIndentBlockOperationsForFromClause(list, fromClause);
                     }
                 }