Disabling ordering when using count() operator in Linq statement gene…

…ration. Closes GH-2580

src/LinqTests/Operators/any_operator.cs

@@ -41,6 +41,18 @@ public void naked_any_hit()
         theSession.Query<Target>().Any().ShouldBeTrue();
     }
 
+    [Fact]
+    public async Task any_should_ignore_order()
+    {
+        theSession.Store(new Target { Number = 1 });
+        theSession.Store(new Target { Number = 2 });
+        theSession.Store(new Target { Number = 3 });
+        theSession.Store(new Target { Number = 4 });
+        await theSession.SaveChangesAsync();
+
+        (await theSession.Query<Target>().OrderBy(x => x.Number).AnyAsync()).ShouldBeTrue();
+    }
+
     [Fact]
     public void any_hit_with_only_one_document()
     {

src/LinqTests/Operators/count_operator.cs

@@ -21,6 +21,18 @@ public void count_without_any_where()
         theSession.Query<Target>().Count().ShouldBe(4);
     }
 
+    [Fact]
+    public async Task count_ignores_order_by()
+    {
+        theSession.Store(new Target { Number = 1 });
+        theSession.Store(new Target { Number = 2 });
+        theSession.Store(new Target { Number = 3 });
+        theSession.Store(new Target { Number = 4 });
+        await theSession.SaveChangesAsync();
+
+        (await theSession.Query<Target>().OrderBy(x => x.Number).CountAsync()).ShouldBe(4);
+    }
+
     [Fact]
     public void long_count_without_any_where()
     {

src/Marten/Linq/CollectionUsage.Compilation.cs

@@ -254,6 +254,10 @@ internal void ProcessSingleValueModeIfAny(SelectorStatement statement)
                     break;
 
                 case Marten.Linq.Parsing.SingleValueMode.Count:
+                    // Invalid to be using OrderBy() while also using Count() in
+                    // PostgreSQL. Thank you Hot Chocolate.
+                    statement.Ordering.Expressions.Clear();
+
                     if (statement.IsDistinct)
                     {
                         throw new NotImplementedException("Not yet");