[AST] Remove 'is super' bit on ApplyExpr

This appears to be equivalent to
`getArg()->isSuperExpr()`. Let's use that instead.

Author: hamishknight

include/swift/AST/Expr.h

@@ -4444,16 +4444,16 @@ class ApplyExpr : public Expr {
   /// The function being called.
   Expr *Fn;
 
-  /// The argument being passed to it, and whether it's a 'super' argument.
-  llvm::PointerIntPair<Expr *, 1, bool> ArgAndIsSuper;
+  /// The argument being passed to it.
+  Expr *Arg;
 
   /// Returns true if \c e could be used as the call's argument. For most \c ApplyExpr
   /// subclasses, this means it is a \c ParenExpr or \c TupleExpr.
   bool validateArg(Expr *e) const;
 
 protected:
   ApplyExpr(ExprKind Kind, Expr *Fn, Expr *Arg, bool Implicit, Type Ty = Type())
-    : Expr(Kind, Implicit, Ty), Fn(Fn), ArgAndIsSuper(Arg, false) {
+    : Expr(Kind, Implicit, Ty), Fn(Fn), Arg(Arg) {
     assert(classof((Expr*)this) && "ApplyExpr::classof out of date");
     assert(validateArg(Arg) && "Arg is not a permitted expr kind");
     Bits.ApplyExpr.ThrowsIsSet = false;
@@ -4466,15 +4466,10 @@ class ApplyExpr : public Expr {
   void setFn(Expr *e) { Fn = e; }
   Expr *getSemanticFn() const { return Fn->getSemanticsProvidingExpr(); }
 
-  Expr *getArg() const { return ArgAndIsSuper.getPointer(); }
+  Expr *getArg() const { return Arg; }
   void setArg(Expr *e) {
     assert(validateArg(e) && "Arg is not a permitted expr kind");
-    ArgAndIsSuper = {e, ArgAndIsSuper.getInt()};
-  }
-  
-  bool isSuper() const { return ArgAndIsSuper.getInt(); }
-  void setIsSuper(bool super) {
-    ArgAndIsSuper = {ArgAndIsSuper.getPointer(), super};
+    Arg = e;
   }
 
   /// Has the type-checker set the 'throws' bit yet?

lib/AST/ASTDumper.cpp

@@ -2621,8 +2621,6 @@ class PrintExpr : public ExprVisitor<PrintExpr> {
 
   void printApplyExpr(ApplyExpr *E, const char *NodeName) {
     printCommon(E, NodeName);
-    if (E->isSuper())
-      PrintWithColorRAII(OS, ExprModifierColor) << " super";
     if (E->isThrowsSet()) {
       PrintWithColorRAII(OS, ExprModifierColor)
         << (E->throws() ? " throws" : " nothrow");

lib/AST/ASTVerifier.cpp

@@ -1821,12 +1821,6 @@ class Verifier : public ASTWalker {
         }
       }
 
-      if (E->isSuper() != E->getArg()->isSuperExpr()) {
-        Out << "Function application's isSuper() bit mismatch.\n";
-        E->dump(Out);
-        Out << "\n";
-        abort();
-      }
       verifyCheckedBase(E);
     }
 

lib/SILGen/SILGenApply.cpp

@@ -850,7 +850,7 @@ class SILGenApply : public Lowering::ExprVisitor<SILGenApply> {
     if (isMethodSelfApply(e->getFn())) {
       selfApply = cast<ApplyExpr>(e->getFn());
 
-      if (selfApply->isSuper()) {
+      if (selfApply->getArg()->isSuperExpr()) {
         applySuper(selfApply);
         return;
       }

lib/Sema/CSApply.cpp

@@ -1179,9 +1179,6 @@ namespace {
       selfCall->setType(refTy->getResult());
       cs.cacheType(selfCall);
 
-      if (selfParamRef->isSuperExpr())
-        selfCall->setIsSuper(true);
-
       auto &appliedWrappers = solution.appliedPropertyWrappers[locator.getAnchor()];
       if (!appliedWrappers.empty()) {
         auto fnDecl = AnyFunctionRef(dyn_cast<AbstractFunctionDecl>(member));
@@ -7749,9 +7746,6 @@ Expr *ExprRewriter::finishApply(ApplyExpr *apply, Type openedType,
 
   apply->setFn(fn);
 
-  // Check whether the argument is 'super'.
-  bool isSuper = apply->getArg()->isSuperExpr();
-
   // For function application, convert the argument to the input type of
   // the function.
   SmallVector<Identifier, 2> argLabelsScratch;
@@ -7768,7 +7762,6 @@ Expr *ExprRewriter::finishApply(ApplyExpr *apply, Type openedType,
 
     apply->setArg(arg);
     cs.setType(apply, fnType->getResult());
-    apply->setIsSuper(isSuper);
 
     solution.setExprTypes(apply);
     Expr *result = TypeChecker::substituteInputSugarTypeForResult(apply);

lib/Sema/CodeSynthesis.cpp

@@ -626,7 +626,6 @@ synthesizeDesignatedInitOverride(AbstractFunctionDecl *fn, void *context) {
     type = funcTy->getResult();
   auto *superclassCtorRefExpr =
       new (ctx) DotSyntaxCallExpr(ctorRefExpr, SourceLoc(), superRef, type);
-  superclassCtorRefExpr->setIsSuper(true);
   superclassCtorRefExpr->setThrows(false);
 
   auto *bodyParams = ctor->getParameters();