[Linked expression analyzer] Stop tracking anonymous closure params.

A given instance of an anonymous closure parameter will always have
the same type (or type variable). This wasn't true when the linked
expression analyzer was implemented, but it is guaranteed now.

Author: DougGregor

lib/Sema/CSGen.cpp

@@ -91,10 +91,6 @@ namespace {
 
     llvm::SmallVector<BinaryExpr *, 4> binaryExprs;
 
-    // TODO: manage as a set of lists, to speed up addition of binding
-    // constraints.
-    llvm::SmallVector<DeclRefExpr *, 16> anonClosureParams;
-    
     LinkedTypeInfo() {
       haveIntLiteral = false;
       haveFloatLiteral = false;
@@ -249,10 +245,7 @@ namespace {
 
       if (auto DRE = dyn_cast<DeclRefExpr>(expr)) {
         if (auto varDecl = dyn_cast<VarDecl>(DRE->getDecl())) {
-          if (isa<ParamDecl>(varDecl) &&
-              cast<ParamDecl>(varDecl)->isAnonClosureParam()) {
-            LTI.anonClosureParams.push_back(DRE);
-          } else if (CS.hasType(DRE)) {
+          if (CS.hasType(DRE)) {
             LTI.collectedTypes.insert(CS.getType(DRE).getPointer());
           }
           return { false, expr };
@@ -346,24 +339,6 @@ namespace {
 
     expr->walk(LinkedExprAnalyzer(lti, CS));
 
-    // Link anonymous closure params of the same index.
-    // TODO: As stated above, we should bucket these whilst collecting the
-    // exprs to avoid quadratic behavior.
-    for (auto acp1 : lti.anonClosureParams) {
-      for (auto acp2 : lti.anonClosureParams) {
-        if (acp1 == acp2)
-          continue;
-
-        if (acp1->getDecl()->getBaseName() == acp2->getDecl()->getBaseName()) {
-
-          auto tyvar1 = CS.getType(acp1)->getAs<TypeVariableType>();
-          auto tyvar2 = CS.getType(acp2)->getAs<TypeVariableType>();
-
-          mergeRepresentativeEquivalenceClasses(CS, tyvar1, tyvar2);
-        }
-      }
-    }
-
     auto mergeTypeVariables = [&](ArrayRef<TypeVariableType *> typeVars) {
       if (typeVars.size() < 2)
         return;