Fix static vars trying to reference local vars, and add pragma

DMCompiler/Compiler/CompilerError.cs

@@ -50,6 +50,7 @@ public enum WarningCode {
     PointlessScopeOperator = 2209,
     PointlessPositionalArgument = 2210,
     ProcArgumentGlobal = 2211, // Prepending "/" on a proc arg (e.g. "/proc/example(/var/foo)" makes the arg a global var. Ref https://www.byond.com/forum/post/2830750
+    AmbiguousVarStatic = 2212, // Referencing a static variable when an instance variable with the same name exists
     MalformedRange = 2300,
     InvalidRange = 2301,
     InvalidSetStatement = 2302,

DMCompiler/DM/Builders/DMExpressionBuilder.cs

@@ -554,13 +554,16 @@ private static DMExpression BuildIdentifier(DMASTIdentifier identifier, DMObject
                 }
 
                 var field = dmObject.GetVariable(name);
-                if (field != null) {
+                if (field != null && CurrentScopeMode == ScopeMode.Normal) {
                     return new Field(identifier.Location, field, field.ValType);
                 }
 
                 var globalId = proc?.GetGlobalVariableId(name) ?? dmObject.GetGlobalVariableId(name);
 
                 if (globalId != null) {
+                    if (field is not null)
+                        DMCompiler.Emit(WarningCode.AmbiguousVarStatic, identifier.Location, $"Static var definition cannot reference instance variable \"{name}\" but a global exists");
+
                     var globalVar = DMObjectTree.Globals[globalId.Value];
                     var global = new GlobalField(identifier.Location, globalVar.Type, globalId.Value, globalVar.ValType);
                     return global;

DMCompiler/DM/Builders/DMProcBuilder.cs

@@ -350,8 +350,11 @@ public void ProcessStatementSpawn(DMASTProcStatementSpawn statementSpawn) {
             proc.AddLabel(afterSpawnLabel);
         }
 
+        /// <remarks>
+        /// Global/static var declarations are handled by <see cref="DMCodeTree.ProcGlobalVarNode" />
+        /// </remarks>
         public void ProcessStatementVarDeclaration(DMASTProcStatementVarDeclaration varDeclaration) {
-            if (varDeclaration.IsGlobal) { return; } //Currently handled by DMObjectBuilder
+            if (varDeclaration.IsGlobal) { return; }
 
             DMExpression value;
             if (varDeclaration.Value != null) {

DMCompiler/DMStandard/DefaultPragmaConfig.dm

@@ -32,6 +32,7 @@
 #pragma SuspiciousSwitchCase warning
 #pragma PointlessPositionalArgument warning
 #pragma ProcArgumentGlobal warning // Ref BYOND issue https://www.byond.com/forum/post/2830750
+#pragma AmbiguousVarStatic warning // https://github.com/OpenDreamProject/OpenDream/issues/997
 // NOTE: The next few pragmas are for OpenDream's experimental type checker
 // This feature is still in development, elevating these pragmas outside of local testing is discouraged
 // An RFC to finalize this feature is coming soon(TM)
@@ -48,7 +49,7 @@
 #pragma EmptyBlock notice
 #pragma EmptyProc disabled // NOTE: If you enable this in OD's default pragma config file, it will emit for OD's DMStandard. Put it in your codebase's pragma config file.
 #pragma UnsafeClientAccess disabled // NOTE: Only checks for unsafe accesses like "client.foobar" and doesn't consider if the client was already null-checked earlier in the proc
-#pragma AssignmentInConditional warning 
+#pragma AssignmentInConditional warning
 #pragma PickWeightedSyntax disabled
 #pragma AmbiguousInOrder warning
 #pragma RuntimeSearchOperator disabled