Dealing with literal boolean values in complex WHERE clauses. Closes G…

…H-2850

src/LinqTests/Bugs/Bug_2850_missed_field_reducing.cs

@@ -0,0 +1,31 @@
+using System.Linq;
+using System.Threading.Tasks;
+using Marten;
+using Marten.Testing.Documents;
+using Marten.Testing.Harness;
+using Shouldly;
+
+namespace LinqTests.Bugs;
+
+public class Bug_2850_missed_field_reducing : BugIntegrationContext
+{
+    public async Task RunQuery(bool include, int resultCount)
+    {
+        var results = await theSession.Query<Target>().Where(x => include || !x.Flag).CountAsync();
+        results.ShouldBe(resultCount);
+    }
+
+    [Fact]
+    public async Task pass_bool_into_query()
+    {
+        await theStore.Advanced.Clean.DeleteDocumentsByTypeAsync(typeof(Target));
+
+        var targets = Target.GenerateRandomData(100).ToArray();
+        await theStore.BulkInsertAsync(targets);
+
+        var count = targets.Count(x => x.Flag);
+
+        await RunQuery(true, 100);
+        await RunQuery(false, 100 - count);
+    }
+}

src/Marten/Linq/Parsing/WhereClauseParser.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq.Expressions;
 using Marten.Exceptions;
 using Marten.Linq.Members;
@@ -49,6 +50,13 @@ protected override Expression VisitMember(MemberExpression node)
     {
         if (node.Type == typeof(bool))
         {
+            // Check if it's a literal field. See https://github.com/JasperFx/marten/issues/2850
+            if (node.TryToParseConstant(out var constant))
+            {
+                _holder.Register(constant.Value.Equals(true) ? new WhereFragment("true") : new WhereFragment("false"));
+                return null;
+            }
+
             var field = _members.MemberFor(node);
             if (field is IBooleanField b)
             {
@@ -65,18 +73,6 @@ protected override Expression VisitMember(MemberExpression node)
         return base.VisitMember(node);
     }
 
-    private IQueryableMember? findHoldingMember(SimpleExpression? @object, SimpleExpression[] arguments)
-    {
-        if (@object?.Member != null) return @object.Member;
-
-        foreach (var argument in arguments)
-        {
-            if (argument.Member != null) return argument.Member;
-        }
-
-        return null;
-    }
-
     protected override Expression VisitMethodCall(MethodCallExpression node)
     {
         var parser = _options.Linq.FindMethodParser(node);
@@ -162,6 +158,10 @@ protected override Expression VisitUnary(UnaryExpression node)
 
             return returnValue;
         }
+        else if (node.NodeType == ExpressionType.OrElse)
+        {
+            Debug.WriteLine(node);
+        }
 
         return null;
     }