[CS] NFC: Rename VarRefCollector -> TypeVarRefCollector

Author: hamishknight

include/swift/Sema/ConstraintSystem.h

@@ -6238,18 +6238,22 @@ class ConjunctionElementProducer : public BindingProducer<ConjunctionElement> {
   }
 };
 
-/// Find any references to not yet resolved outer VarDecls (including closure
-/// parameters) used in the body of a conjunction element (e.g closures, taps,
-/// if/switch expressions). This is required because isolated conjunctions, just
-/// like single-expression closures, have to be connected to type variables they
-/// are going to use, otherwise they'll get placed in a separate solver
-/// component and would never produce a solution.
-class VarRefCollector : public ASTWalker {
+/// Find any references to external type variables used in the body of a
+/// conjunction element (e.g closures, taps, if/switch expressions).
+///
+/// This includes:
+/// - Not yet resolved outer VarDecls (including closure parameters)
+///
+/// This is required because isolated conjunctions, just like single-expression
+/// closures, have to be connected to type variables they are going to use,
+/// otherwise they'll get placed in a separate solver component and would never
+/// produce a solution.
+class TypeVarRefCollector : public ASTWalker {
   ConstraintSystem &CS;
   llvm::SmallSetVector<TypeVariableType *, 4> TypeVars;
 
 public:
-  VarRefCollector(ConstraintSystem &cs) : CS(cs) {}
+  TypeVarRefCollector(ConstraintSystem &cs) : CS(cs) {}
 
   /// Infer the referenced type variables from a given decl.
   void inferTypeVars(Decl *D);

lib/Sema/CSGen.cpp

@@ -866,7 +866,7 @@ namespace {
   };
 } // end anonymous namespace
 
-void VarRefCollector::inferTypeVars(Decl *D) {
+void TypeVarRefCollector::inferTypeVars(Decl *D) {
   // We're only interested in VarDecls.
   if (!isa_and_nonnull<VarDecl>(D))
     return;
@@ -881,7 +881,7 @@ void VarRefCollector::inferTypeVars(Decl *D) {
 }
 
 ASTWalker::PreWalkResult<Expr *>
-VarRefCollector::walkToExprPre(Expr *expr) {
+TypeVarRefCollector::walkToExprPre(Expr *expr) {
   if (auto *DRE = dyn_cast<DeclRefExpr>(expr))
     inferTypeVars(DRE->getDecl());
 
@@ -1304,7 +1304,7 @@ namespace {
           // in the tap body, otherwise tap expression is going
           // to get disconnected from the context.
           if (auto *body = tap->getBody()) {
-            VarRefCollector refCollector(CS);
+            TypeVarRefCollector refCollector(CS);
 
             body->walk(refCollector);
 
@@ -2938,7 +2938,7 @@ namespace {
       auto *locator = CS.getConstraintLocator(closure);
       auto closureType = CS.createTypeVariable(locator, TVO_CanBindToNoEscape);
 
-      VarRefCollector refCollector(CS);
+      TypeVarRefCollector refCollector(CS);
       // Walk the capture list if this closure has one,  because it could
       // reference declarations from the outer closure.
       if (auto *captureList =

lib/Sema/CSSyntacticElement.cpp

@@ -335,7 +335,7 @@ static void createConjunction(ConstraintSystem &cs,
     isIsolated = true;
   }
 
-  VarRefCollector paramCollector(cs);
+  TypeVarRefCollector paramCollector(cs);
 
   // Whether we're doing completion, and the conjunction is for a
   // SingleValueStmtExpr, or one of its braces.