[ConstraintLocator] Add key path component lookup

Author: Amritpan Kaur

include/swift/Sema/ConstraintLocator.h

@@ -275,6 +275,9 @@ class ConstraintLocator : public llvm::FoldingSetNode {
   /// a key path component.
   bool isForKeyPathComponentResult() const;
 
+  /// Determine whether this locator points to a key path component.
+  bool isForKeyPathComponent() const;
+
   /// Determine whether this locator points to the generic parameter.
   bool isForGenericParameter() const;
 

lib/Sema/ConstraintLocator.cpp

@@ -598,6 +598,10 @@ bool ConstraintLocator::isForKeyPathComponentResult() const {
   return isLastElement<LocatorPathElt::KeyPathComponentResult>();
 }
 
+bool ConstraintLocator::isForKeyPathComponent() const {
+  return isLastElement<LocatorPathElt::KeyPathComponent>();
+}
+
 bool ConstraintLocator::isForGenericParameter() const {
   return isLastElement<LocatorPathElt::GenericParameter>();
 }