Revert "[Constraint solver] De-duplicate potential throw sites when merging partial solutions"

This reverts commit 8e50528. We need more
work on this part of the code.

Author: DougGregor

include/swift/Sema/ConstraintSystem.h

@@ -1466,15 +1466,6 @@ struct PotentialThrowSite {
 
   /// The locator that specifies where the throwing operation occurs.
   ConstraintLocator *locator;
-  
-  friend bool operator==(const PotentialThrowSite& lhs, const PotentialThrowSite &rhs) {
-    return lhs.kind == rhs.kind && lhs.type.getPointer() == rhs.type.getPointer() &&
-           lhs.locator == rhs.locator;
-  }
-  
-  friend bool operator!=(const PotentialThrowSite& lhs, const PotentialThrowSite &rhs) {
-    return !(lhs == rhs);
-  }
 };
 
 /// A complete solution to a constraint system.

lib/Sema/CSSolver.cpp

@@ -353,21 +353,9 @@ void ConstraintSystem::applySolution(const Solution &solution) {
       setCaseLabelItemInfo(info.first, info.second);
   }
 
-  if (!potentialThrowSites.empty() && !solution.potentialThrowSites.empty()) {
-    DenseMap<void *, std::vector<PotentialThrowSite>> known;
-    for (const auto &throwSite : potentialThrowSites) {
-      known[throwSite.first.getOpaqueValue()].push_back(throwSite.second);
-    }
-      
-    for (const auto &throwSite : solution.potentialThrowSites) {
-      auto &sites = known[throwSite.first.getOpaqueValue()];
-      if (std::find(sites.begin(), sites.end(), throwSite.second) != sites.end())
-        continue;
-      
-      sites.push_back(throwSite.second);
-      potentialThrowSites.push_back(throwSite);
-    }
-  }
+  potentialThrowSites.insert(potentialThrowSites.end(),
+                             solution.potentialThrowSites.begin(),
+                             solution.potentialThrowSites.end());
 
   for (auto param : solution.isolatedParams) {
     isolatedParams.insert(param);