[Clang][P1061] Clean up stuff

Author: ricejasonf

clang/lib/Sema/SemaDeclCXX.cpp

@@ -963,7 +963,6 @@ Sema::ActOnDecompositionDeclarator(Scope *S, Declarator &D,
 //  - Checks the arity of the structured bindings
 //  - Creates the resolved pack expr if there is
 //    one
-
 static bool CheckBindingsCount(Sema &S, DecompositionDecl *DD,
                                QualType DecompType,
                                ArrayRef<BindingDecl *> Bindings,
@@ -1621,6 +1620,7 @@ void Sema::CheckCompleteDecompositionDeclaration(DecompositionDecl *DD) {
   // each binding.
   if (DecompType->isDependentType()) {
     for (auto *B : DD->bindings()) {
+      // Do not overwrite any pack type.
       if (B->getType().isNull())
         B->setType(Context.DependentTy);
     }

clang/lib/Sema/SemaTemplateInstantiateDecl.cpp

@@ -1180,8 +1180,11 @@ Decl *TemplateDeclInstantiator::VisitDecompositionDecl(DecompositionDecl *D) {
   ResolvedUnexpandedPackExpr *OldResolvedPack = nullptr;
   for (auto *OldBD : D->bindings()) {
     Expr *BindingExpr = OldBD->getBinding();
-    if (auto *RP = dyn_cast_if_present<ResolvedUnexpandedPackExpr>(BindingExpr))
+    if (auto *RP =
+            dyn_cast_if_present<ResolvedUnexpandedPackExpr>(BindingExpr)) {
+      assert(!OldResolvedPack && "no more than one pack is allowed");
       OldResolvedPack = RP;
+    }
     NewBindings.push_back(cast<BindingDecl>(VisitBindingDecl(OldBD)));
   }
   ArrayRef<BindingDecl*> NewBindingArray = NewBindings;
@@ -1197,13 +1200,13 @@ Decl *TemplateDeclInstantiator::VisitDecompositionDecl(DecompositionDecl *D) {
     // Mark the holding vars (if any) in the pack as instantiated since
     // they are created implicitly.
     auto Bindings = NewDD->bindings();
-    auto BPack = std::find_if(
-        Bindings.begin(), Bindings.end(),
-        [](BindingDecl *D) -> bool { return D->isParameterPack(); });
+    auto BPack = llvm::find_if(
+        Bindings, [](BindingDecl *D) -> bool { return D->isParameterPack(); });
     auto *NewResolvedPack =
         cast<ResolvedUnexpandedPackExpr>((*BPack)->getBinding());
     auto OldExprs = OldResolvedPack->getExprs();
     auto NewExprs = NewResolvedPack->getExprs();
+    assert(OldExprs.size() == NewExprs.size());
     for (unsigned I = 0; I < OldResolvedPack->getNumExprs(); I++) {
       DeclRefExpr *OldDRE = cast<DeclRefExpr>(OldExprs[I]);
       BindingDecl *OldNestedBD = cast<BindingDecl>(OldDRE->getDecl());

clang/lib/Sema/SemaTemplateVariadic.cpp

@@ -52,7 +52,7 @@ class CollectUnexpandedParameterPacksVisitor
           return;
       } else if (auto *BD = dyn_cast<BindingDecl>(ND)) {
         Expr *E = BD->getBinding();
-        if (auto *RP = dyn_cast_if_present<ResolvedUnexpandedPackExpr>(E)) {
+        if (auto *RP = cast_if_present<ResolvedUnexpandedPackExpr>(E)) {
           addUnexpanded(RP);
           return;
         }
@@ -818,8 +818,6 @@ bool Sema::CheckParameterPacksForExpansion(
     unsigned NewPackSize, PendingPackExpansionSize = 0;
     if (IsVarDeclPack) {
       // Figure out whether we're instantiating to an argument pack or not.
-      typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack;
-
       llvm::PointerUnion<Decl *, DeclArgumentPack *> *Instantiation =
           CurrentInstantiationScope->findInstantiationOf(
               cast<NamedDecl *>(ParmPack.first));