From e1e538183ac75bf51cab8ad47616b927fe84b6de Mon Sep 17 00:00:00 2001
From: Shpakh-MSFT <10427420+Shpakh-MSFT@users.noreply.github.com>
Date: Fri, 1 Nov 2024 06:11:10 -0700
Subject: [PATCH] =?UTF-8?q?Added=20new=20method=20on=20IExternalRule=20to?=
 =?UTF-8?q?=20help=20with=20invariantexpression=20ch=E2=80=A6=20(#2725)?=
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On an effort to remove null rule binding, we need the ability to have an
option to apply null binding before doing the check if binding is null.
This change adds a new method on IExternalRule to help with that.
---
 .../Microsoft.PowerFx.Core/App/Controls/IExternalRule.cs      | 3 +++
 src/libraries/Microsoft.PowerFx.Core/Binding/Binder.cs        | 4 +---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/libraries/Microsoft.PowerFx.Core/App/Controls/IExternalRule.cs b/src/libraries/Microsoft.PowerFx.Core/App/Controls/IExternalRule.cs
index 408dddfe4f..c29990ee9d 100644
--- a/src/libraries/Microsoft.PowerFx.Core/App/Controls/IExternalRule.cs
+++ b/src/libraries/Microsoft.PowerFx.Core/App/Controls/IExternalRule.cs
@@ -22,5 +22,8 @@ internal interface IExternalRule
 
         // Returns true when Binding is non-null, otherwise false.
         bool HasValidBinding { get; }
+
+        // Returns true when rule is constant.
+        bool IsInvariantExpression { get; }
     }
 }
diff --git a/src/libraries/Microsoft.PowerFx.Core/Binding/Binder.cs b/src/libraries/Microsoft.PowerFx.Core/Binding/Binder.cs
index 937173cb32..4dc0fa0e11 100644
--- a/src/libraries/Microsoft.PowerFx.Core/Binding/Binder.cs
+++ b/src/libraries/Microsoft.PowerFx.Core/Binding/Binder.cs
@@ -3619,9 +3619,7 @@ public override void PostVisit(DottedNameNode node)
                     // we need to mark the node as constant, and save the control info so we may look up the
                     // rule later.
                     if (controlInfo?.GetRule(property.InvariantName) is IExternalRule rule &&
-                        rule.HasValidBinding &&
-                        !rule.HasErrorsOrWarnings &&
-                        rule.Binding.IsConstant(rule.Binding.Top))
+                        rule.IsInvariantExpression)
                     {
                         value = controlInfo;
                         isConstant = true;