[NFC] Sema: Add Solution::getCalleeOverloadChoice

Author: AnthonyLatsis

include/swift/Sema/ConstraintSystem.h

@@ -1753,8 +1753,12 @@ class Solution {
     return *getOverloadChoiceIfAvailable(locator);
   }
 
-  /// Retrieve the overload choice associated with the given
+  /// Retrieve the overload choice for the callee associated with the given
   /// locator.
+  SelectedOverload getCalleeOverloadChoice(ConstraintLocator *locator) const;
+
+  /// Retrieve the overload choice associated with the given
+  /// locator, if any.
   std::optional<SelectedOverload>
   getOverloadChoiceIfAvailable(ConstraintLocator *locator) const {
     auto known = overloadChoices.find(locator);
@@ -1763,6 +1767,11 @@ class Solution {
     return std::nullopt;
   }
 
+  /// Retrieve the overload choice for the callee associated with the given
+  /// locator, if any.
+  std::optional<SelectedOverload>
+  getCalleeOverloadChoiceIfAvailable(ConstraintLocator *locator) const;
+
   std::optional<SyntacticElementTarget>
   getTargetFor(SyntacticElementTargetKey key) const;
 

lib/Sema/CSApply.cpp

@@ -188,6 +188,15 @@ Solution::resolveConcreteDeclRef(ValueDecl *decl,
   return ConcreteDeclRef(decl, subst);
 }
 
+SelectedOverload
+Solution::getCalleeOverloadChoice(ConstraintLocator *locator) const {
+  return getOverloadChoice(getCalleeLocator(locator));
+}
+
+std::optional<SelectedOverload>
+Solution::getCalleeOverloadChoiceIfAvailable(ConstraintLocator *locator) const {
+  return getOverloadChoiceIfAvailable(getCalleeLocator(locator));
+}
 
 ConstraintLocator *Solution::getCalleeLocator(ConstraintLocator *locator,
                                               bool lookThroughApply) const {

lib/Sema/CSDiagnostics.cpp

@@ -9364,10 +9364,9 @@ bool DefaultExprTypeMismatch::diagnoseAsError() {
   emitDiagnostic(diag::cannot_convert_default_value_type_to_argument_type,
                  getFromType(), getToType(), paramIdx);
 
-  auto overload = getCalleeOverloadChoiceIfAvailable(locator);
-  assert(overload);
+  auto overload = getSolution().getCalleeOverloadChoice(locator);
 
-  auto *PD = getParameterList(overload->choice.getDecl())->get(paramIdx);
+  auto *PD = getParameterList(overload.choice.getDecl())->get(paramIdx);
 
   auto note = emitDiagnosticAt(PD->getLoc(), diag::default_value_declared_here);
 

lib/Sema/CSDiagnostics.h

@@ -149,11 +149,11 @@ class FailureDiagnostic {
     return S.getOverloadChoiceIfAvailable(locator);
   }
 
-  /// Retrieve overload choice resolved for a callee for the anchor
-  /// of a given locator.
+  /// Retrieve the overload choice for the callee associated with the given
+  /// locator, if any.
   std::optional<SelectedOverload>
   getCalleeOverloadChoiceIfAvailable(ConstraintLocator *locator) const {
-    return getOverloadChoiceIfAvailable(S.getCalleeLocator(locator));
+    return S.getCalleeOverloadChoiceIfAvailable(locator);
   }
 
   ConstraintLocator *