[ConstraintSystem] Convert argumentMatchingChoices to a map vector to avoid duplicates

Author: xedin

include/swift/Sema/ConstraintSystem.h

@@ -2394,7 +2394,7 @@ class ConstraintSystem {
 
   /// For locators associated with call expressions, the trailing closure
   /// matching rule and parameter bindings that were applied.
-  std::vector<std::pair<ConstraintLocator *, MatchCallArgumentResult>>
+  llvm::MapVector<ConstraintLocator *, MatchCallArgumentResult>
       argumentMatchingChoices;
 
   /// The set of implicit value conversions performed by the solver on

lib/Sema/CSSimplify.cpp

@@ -11566,7 +11566,7 @@ void ConstraintSystem::recordAnyTypeVarAsPotentialHole(Type type) {
 void ConstraintSystem::recordMatchCallArgumentResult(
     ConstraintLocator *locator, MatchCallArgumentResult result) {
   assert(locator->isLastElement<LocatorPathElt::ApplyArgument>());
-  argumentMatchingChoices.push_back({locator, result});
+  argumentMatchingChoices.insert({locator, result});
 }
 
 ConstraintSystem::SolutionKind ConstraintSystem::simplifyFixConstraint(

lib/Sema/CSSolver.cpp

@@ -245,7 +245,7 @@ void ConstraintSystem::applySolution(const Solution &solution) {
 
   // Remember all of the argument/parameter matching choices we made.
   for (auto &argumentMatch : solution.argumentMatchingChoices) {
-    argumentMatchingChoices.push_back(argumentMatch);
+    argumentMatchingChoices.insert(argumentMatch);
   }
 
   // Register the solution's opened types.