FIX: GetBindingDisplayString returns empty for composites filtered by group-based binding mask [UUM-141423]

Auto-generated by input-fix-pr-prep after input-fix-judge approved the hypothesis from input-fix-deep-dive (after triage Step 5b was rejected on pass 1).

InputActionRebindingExtensions.GetBindingDisplayString(InputAction, InputBinding, InputBinding.DisplayStringOptions) returns empty when the binding mask filters by group, because the per-binding loop skips isPartOfComposite parts but then tests the mask against composite headers which carry no group metadata, so the whole composite drops out.

Jira: https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-141423
Judge rationale: file and method exist, the mechanism is in the method body (lines 321-323), the fall-through reuses the existing scan idiom at lines 444-448 of the same file with no signature/exception/serialization change, no nearby test asserts the buggy current behaviour, no native/threading/unsafe touches in the method or its direct callees at one level, and the previously-cited mixed-group composite edge case is now explicitly addressed via documented atomic-composite semantics grounded in the line-440-492 renderer's existing convention.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: Pauliusd01

Assets/Tests/InputSystem/CoreTests_Actions.cs

@@ -9238,6 +9238,21 @@ public void Actions_WhenGettingDisplayTextForBindingsOnAction_CompositesAreForma
         Assert.That(action.GetBindingDisplayString(8), Is.EqualTo("Left Shift|Right Shift+A"));
     }
 
+    // https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-141423
+    [Test]
+    [Category("Actions")]
+    public void Actions_WhenGettingDisplayTextForBindingsOnAction_CompositeIsIncludedWhenAtLeastOnePartMatchesBindingMask()
+    {
+        var action = new InputAction();
+
+        action.AddCompositeBinding("1DAxis")
+            .With("Negative", "<Keyboard>/a", groups: "Keyboard")
+            .With("Positive", "<Keyboard>/d", groups: "Keyboard");
+
+        Assert.That(action.GetBindingDisplayString(InputBinding.MaskByGroup("Keyboard")),
+            Is.EqualTo("A/D"));
+    }
+
     // https://fogbugz.unity3d.com/f/cases/1321175/
     [Test]
     [Category("Actions")]

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Fixed
 
+- Fixed `InputActionRebindingExtensions.GetBindingDisplayString(InputAction, InputBinding, ...)` returning an empty string for composite bindings when the binding mask filters by group [UUM-141423](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-141423)
 - Fixed a `NullReferenceException` thrown when removing all action maps [UUM-137116](https://jira.unity3d.com/browse/UUM-137116)
 - Simplified default setting messaging by consolidating repetitive messages into a single HelpBox.
 - Fixed a `NullPointerReferenceException` thrown in `InputManagerStateMonitors.FireStateChangeNotifications` logging by adding validation [UUM-136095].

Packages/com.unity.inputsystem/InputSystem/Runtime/Actions/InputActionRebindingExtensions.cs

@@ -321,7 +321,28 @@ public static string GetBindingDisplayString(this InputAction action, InputBindi
                 if (bindings[i].isPartOfComposite)
                     continue;
                 if (!bindingMask.Matches(bindings[i]))
-                    continue;
+                {
+                    // Composites are filtered atomically: any matching part promotes the whole
+                    // composite, consistent with how the integer-index renderer at lines 440-492
+                    // already treats composites as one display unit; per-part filtering would
+                    // require a separate API.
+                    if (!bindings[i].isComposite)
+                        continue;
+                    var lastPartIndex = i + 1;
+                    while (lastPartIndex < bindings.Count && bindings[lastPartIndex].isPartOfComposite)
+                        ++lastPartIndex;
+                    var anyPartMatches = false;
+                    for (var partIndex = i + 1; partIndex < lastPartIndex; ++partIndex)
+                    {
+                        if (bindingMask.Matches(bindings[partIndex]))
+                        {
+                            anyPartMatches = true;
+                            break;
+                        }
+                    }
+                    if (!anyPartMatches)
+                        continue;
+                }
 
                 ////REVIEW: should this filter out bindings that are not resolving to any controls?