[ConstraintLocator] NFC: Introduce a way to determine whether locator points directly to a specific expression

Author: xedin

lib/Sema/ConstraintLocator.cpp

@@ -234,18 +234,15 @@ bool ConstraintLocator::isForContextualType() const {
 }
 
 bool ConstraintLocator::isForAssignment() const {
-  auto *anchor = getAnchor();
-  return anchor && isa<AssignExpr>(anchor) && getPath().empty();
+  return directlyAt<AssignExpr>();
 }
 
 bool ConstraintLocator::isForCoercion() const {
-  auto *anchor = getAnchor();
-  return anchor && isa<CoerceExpr>(anchor) && getPath().empty();
+  return directlyAt<CoerceExpr>();
 }
 
 bool ConstraintLocator::isForOptionalTry() const {
-  auto *anchor = getAnchor();
-  return anchor && isa<OptionalTryExpr>(anchor) && getPath().empty();
+  return directlyAt<OptionalTryExpr>();
 }
 
 GenericTypeParamType *ConstraintLocator::getGenericParameter() const {

lib/Sema/ConstraintLocator.h

@@ -374,6 +374,12 @@ class ConstraintLocator : public llvm::FoldingSetNode {
   /// Determine whether this locator points to the `try?` expression.
   bool isForOptionalTry() const;
 
+  /// Determine whether this locator points directly to a given expression.
+  template <class E> bool directlyAt() const {
+    auto *anchor = getAnchor();
+    return anchor && isa<E>(anchor) && getPath().empty();
+  }
+
   /// Attempts to cast the first path element of the locator to a specific
   /// \c LocatorPathElt subclass, returning \c None if either unsuccessful or
   /// the locator has no path elements.