Revert naming changes to getCalleeLocator & getChoiceFor

In addition, add a document comment to `getCalleeLocator` to clarify
its semantics.

Author: hamishknight

lib/Sema/CSApply.cpp

@@ -4247,7 +4247,7 @@ namespace {
         // Adjust the locator such that it includes any additional elements to
         // point to the component's callee, e.g a SubscriptMember for a
         // subscript component.
-        locator = cs.getAnchormostCalleeLocator(locator);
+        locator = cs.getCalleeLocator(locator);
 
         bool isDynamicMember = false;
         // If this is an unresolved link, make sure we resolved it.

lib/Sema/CSDiagnostics.cpp

@@ -121,14 +121,10 @@ Expr *FailureDiagnostic::getBaseExprFor(Expr *anchor) const {
   return nullptr;
 }
 
-Optional<SelectedOverload> FailureDiagnostic::getAnchormostChoice() const {
-  return getAnchormostChoiceFor(getLocator());
-}
-
 Optional<SelectedOverload>
-FailureDiagnostic::getAnchormostChoiceFor(ConstraintLocator *locator) const {
+FailureDiagnostic::getChoiceFor(ConstraintLocator *locator) const {
   auto &cs = getConstraintSystem();
-  return getOverloadChoiceIfAvailable(cs.getAnchormostCalleeLocator(locator));
+  return getOverloadChoiceIfAvailable(cs.getCalleeLocator(locator));
 }
 
 Type FailureDiagnostic::resolveInterfaceType(Type type,
@@ -163,8 +159,7 @@ Type FailureDiagnostic::resolveInterfaceType(Type type,
 }
 
 /// Given an apply expr, returns true if it is expected to have a direct callee
-/// overload, resolvable using `getAnchormostChoiceFor`. Otherwise, returns
-/// false.
+/// overload, resolvable using `getChoiceFor`. Otherwise, returns false.
 static bool shouldHaveDirectCalleeOverload(const CallExpr *callExpr) {
   auto *fnExpr = callExpr->getDirectCallee();
 
@@ -226,7 +221,7 @@ FailureDiagnostic::getFunctionArgApplyInfo(ConstraintLocator *locator) const {
 
   ValueDecl *callee = nullptr;
   Type rawFnType;
-  if (auto overload = getAnchormostChoiceFor(argLocator)) {
+  if (auto overload = getChoiceFor(argLocator)) {
     // If we have resolved an overload for the callee, then use that to get the
     // function type and callee.
     callee = overload->choice.getDeclOrNull();
@@ -380,7 +375,7 @@ ValueDecl *RequirementFailure::getDeclRef() const {
   if (isFromContextualType())
     return getAffectedDeclFromType(cs.getContextualType());
 
-  if (auto overload = getAnchormostChoice()) {
+  if (auto overload = getChoiceFor(getLocator())) {
     // If there is a declaration associated with this
     // failure e.g. an overload choice of the call
     // expression, let's see whether failure is
@@ -752,7 +747,7 @@ bool LabelingFailure::diagnoseAsNote() {
     return "(" + str + ")";
   };
 
-  auto selectedOverload = getAnchormostChoice();
+  auto selectedOverload = getChoiceFor(getLocator());
   if (!selectedOverload)
     return false;
 
@@ -3127,7 +3122,7 @@ bool AllowTypeOrInstanceMemberFailure::diagnoseAsError() {
       };
 
       auto *baseLoc = cs.getConstraintLocator(ctorRef->getBase());
-      if (auto selection = getAnchormostChoiceFor(baseLoc)) {
+      if (auto selection = getChoiceFor(baseLoc)) {
         OverloadChoice choice = selection->choice;
         if (choice.isDecl() && isMutable(choice.getDecl()) &&
             !isCallArgument(initCall) &&
@@ -4287,7 +4282,7 @@ bool MutatingMemberRefOnImmutableBase::diagnoseAsError() {
 }
 
 bool InvalidTupleSplatWithSingleParameterFailure::diagnoseAsError() {
-  auto selectedOverload = getAnchormostChoice();
+  auto selectedOverload = getChoiceFor(getLocator());
   if (!selectedOverload || !selectedOverload->choice.isDecl())
     return false;
 

lib/Sema/CSDiagnostics.h

@@ -176,13 +176,9 @@ class FailureDiagnostic {
   /// reference or subscript, nullptr otherwise.
   Expr *getArgumentExprFor(Expr *anchor) const;
 
-  /// \returns The overload choice made by the constraint system for the callee
-  /// of this failure's raw anchor, or \c None if no such choice can be found.
-  Optional<SelectedOverload> getAnchormostChoice() const;
-
   /// \returns The overload choice made by the constraint system for the callee
   /// of a given locator's anchor, or \c None if no such choice can be found.
-  Optional<SelectedOverload> getAnchormostChoiceFor(ConstraintLocator *) const;
+  Optional<SelectedOverload> getChoiceFor(ConstraintLocator *) const;
 
   /// For a given locator describing a function argument conversion, or a
   /// constraint within an argument conversion, returns information about the

lib/Sema/CSGen.cpp

@@ -3023,8 +3023,8 @@ namespace {
         }
 
         case KeyPathExpr::Component::Kind::TupleElement: {
-          // Note: If implemented, the logic in `getAnchormostCalleeLocator`
-          // will need updating to return the correct callee locator for this.
+          // Note: If implemented, the logic in `getCalleeLocator` will need
+          // updating to return the correct callee locator for this.
           llvm_unreachable("not implemented");
           break;
         }

lib/Sema/ConstraintSystem.cpp

@@ -414,7 +414,7 @@ ConstraintLocator *ConstraintSystem::getConstraintLocator(
 }
 
 ConstraintLocator *
-ConstraintSystem::getAnchormostCalleeLocator(ConstraintLocator *locator) {
+ConstraintSystem::getCalleeLocator(ConstraintLocator *locator) {
   auto *anchor = locator->getAnchor();
   assert(anchor && "Expected an anchor!");
 
@@ -2497,7 +2497,7 @@ bool ConstraintSystem::diagnoseAmbiguityWithFixes(
       return false;
 
     const auto *fix = fixes.front();
-    auto *calleeLocator = getAnchormostCalleeLocator(fix->getLocator());
+    auto *calleeLocator = getCalleeLocator(fix->getLocator());
     if (commonCalleeLocator && commonCalleeLocator != calleeLocator)
       return false;
 
@@ -2875,7 +2875,7 @@ ConstraintSystem::getArgumentInfoLocator(ConstraintLocator *locator) {
     return getConstraintLocator(fnExpr);
   }
 
-  return getAnchormostCalleeLocator(locator);
+  return getCalleeLocator(locator);
 }
 
 Optional<ConstraintSystem::ArgumentInfo>

lib/Sema/ConstraintSystem.h

@@ -2023,7 +2023,12 @@ class ConstraintSystem {
   /// - For a function application anchor, this will be a locator describing the
   /// 'direct callee' of the call. For example, for the expression \c x.foo?()
   /// the returned locator will describe the member \c foo.
-  ConstraintLocator *getAnchormostCalleeLocator(ConstraintLocator *locator);
+  ///
+  /// Note that because this function deals with the anchor, given a locator
+  /// anchored on \c functionA(functionB()) with path elements pointing to the
+  /// argument \c functionB(), the returned callee locator will describe
+  /// \c functionA rather than \c functionB.
+  ConstraintLocator *getCalleeLocator(ConstraintLocator *locator);
 
 public: