From 487a30cc3a59c832f04f7354f2412d3f736da032 Mon Sep 17 00:00:00 2001
From: wixoa <wixoag@gmail.com>
Date: Fri, 17 Jan 2025 19:57:48 -0500
Subject: [PATCH] Fix var blocks creating an empty type named `var` (#2173)

---
 .../Compiler/DM/AST/DMAST.ObjectStatements.cs |  6 +++
 DMCompiler/Compiler/DM/DMParser.cs            | 41 ++++++++++++++-----
 DMCompiler/DM/Builders/DMCodeTreeBuilder.cs   |  2 +
 3 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/DMCompiler/Compiler/DM/AST/DMAST.ObjectStatements.cs b/DMCompiler/Compiler/DM/AST/DMAST.ObjectStatements.cs
index a0f4f9dd81..ff3d8319ec 100644
--- a/DMCompiler/Compiler/DM/AST/DMAST.ObjectStatements.cs
+++ b/DMCompiler/Compiler/DM/AST/DMAST.ObjectStatements.cs
@@ -7,6 +7,12 @@ namespace DMCompiler.Compiler.DM.AST;
 /// </summary>
 public abstract class DMASTStatement(Location location) : DMASTNode(location);
 
+/// <summary>
+/// Used when there was an error parsing a statement
+/// </summary>
+/// <remarks>Emit an error code before creating!</remarks>
+public sealed class DMASTInvalidStatement(Location location) : DMASTStatement(location);
+
 public sealed class DMASTObjectDefinition(Location location, DreamPath path, DMASTBlockInner? innerBlock)
     : DMASTStatement(location) {
     /// <summary> Unlike other Path variables stored by AST nodes, this path is guaranteed to be the real, absolute path of this object definition block. <br/>
diff --git a/DMCompiler/Compiler/DM/DMParser.cs b/DMCompiler/Compiler/DM/DMParser.cs
index c66199337f..2949029862 100644
--- a/DMCompiler/Compiler/DM/DMParser.cs
+++ b/DMCompiler/Compiler/DM/DMParser.cs
@@ -268,17 +268,28 @@ public DMASTFile File() {
                 return new DMASTProcDefinition(loc, CurrentPath, parameters.ToArray(), procBlock, types);
             }
 
-            //Object definition
-            if (Block() is { } block) {
-                Compiler.VerbosePrint($"Parsed object {CurrentPath}");
-                return new DMASTObjectDefinition(loc, CurrentPath, block);
-            }
-
             //Var definition(s)
             if (CurrentPath.FindElement("var") != -1) {
+                bool isIndented = false;
                 DreamPath varPath = CurrentPath;
                 List<DMASTObjectVarDefinition> varDefinitions = new();
 
+                var possibleNewline = Current();
+                if (Newline()) {
+                    if (Check(TokenType.DM_Indent)) {
+                        isIndented = true;
+                        DMASTPath? newVarPath = Path();
+                        if (newVarPath == null) {
+                            Emit(WarningCode.InvalidVarDefinition, "Expected a var definition");
+                            return new DMASTInvalidStatement(CurrentLoc);
+                        }
+
+                        varPath = CurrentPath.AddToPath(newVarPath.Path.PathString);
+                    } else {
+                        ReuseToken(possibleNewline);
+                    }
+                }
+
                 while (true) {
                     Whitespace();
 
@@ -304,24 +315,26 @@ public DMASTFile File() {
                     var varDef = new DMASTObjectVarDefinition(loc, varPath, value, valType);
 
                     varDefinitions.Add(varDef);
-                    if (Check(TokenType.DM_Comma)) {
+                    if (Check(TokenType.DM_Comma) || (isIndented && Newline())) {
                         Whitespace();
                         DMASTPath? newVarPath = Path();
 
                         if (newVarPath == null) {
                             Emit(WarningCode.InvalidVarDefinition, "Expected a var definition");
                             break;
-                        } else if (newVarPath.Path.Elements.Length > 1) { // TODO: This is valid DM
-                            Emit(WarningCode.BadToken, newVarPath.Location, "Invalid var name");
-                            break;
                         }
 
-                        varPath = CurrentPath.AddToPath("../" + newVarPath.Path.PathString);
+                        varPath = CurrentPath.AddToPath(
+                            isIndented ? newVarPath.Path.PathString
+                                       : "../" + newVarPath.Path.PathString);
                     } else {
                         break;
                     }
                 }
 
+                if (isIndented)
+                    Consume(TokenType.DM_Dedent, "Expected end of var block");
+
                 return (varDefinitions.Count == 1)
                     ? varDefinitions[0]
                     : new DMASTMultipleObjectVarDefinitions(loc, varDefinitions.ToArray());
@@ -336,6 +349,12 @@ public DMASTFile File() {
                 return new DMASTObjectVarOverride(loc, CurrentPath, value);
             }
 
+            //Object definition
+            if (Block() is { } block) {
+                Compiler.VerbosePrint($"Parsed object {CurrentPath}");
+                return new DMASTObjectDefinition(loc, CurrentPath, block);
+            }
+
             //Empty object definition
             Compiler.VerbosePrint($"Parsed object {CurrentPath} - empty");
             return new DMASTObjectDefinition(loc, CurrentPath, null);
diff --git a/DMCompiler/DM/Builders/DMCodeTreeBuilder.cs b/DMCompiler/DM/Builders/DMCodeTreeBuilder.cs
index c4b558c95d..612576368e 100644
--- a/DMCompiler/DM/Builders/DMCodeTreeBuilder.cs
+++ b/DMCompiler/DM/Builders/DMCodeTreeBuilder.cs
@@ -40,6 +40,8 @@ private void ProcessStatement(DMASTStatement statement, DreamPath currentType) {
         }
 
         switch (statement) {
+            case DMASTInvalidStatement:
+                break; // An error should have been emitted by whatever made this
             case DMASTObjectDefinition objectDefinition:
                 CodeTree.AddType(objectDefinition.Path);
                 if (objectDefinition.InnerBlock != null)