[Clang][P1016] Address nits; Remove unneeded code

Author: ricejasonf

clang/include/clang/AST/DeclCXX.h

@@ -4201,7 +4201,7 @@ class DecompositionDecl final
                             getTrailingObjects<BindingDecl *>());
     for (auto *B : Bindings) {
       B->setDecomposedDecl(this);
-      if (B->isParameterPack()) {
+      if (B->isParameterPack() && B->getBinding()) {
         for (Expr *E : B->getBindingPackExprs()) {
           auto *DRE = cast<DeclRefExpr>(E);
           auto *NestedB = cast<BindingDecl>(DRE->getDecl());
@@ -4251,8 +4251,6 @@ class DecompositionDecl final
       return cast<BindingDecl>(DRE->getDecl());
     });
 
-    // llvm::concat must take temporaries or it will capture
-    // references.
     return llvm::concat<BindingDecl *>(std::move(S1), std::move(S2),
                                        std::move(Bindings));
   }

clang/include/clang/AST/Expr.h

@@ -1482,12 +1482,6 @@ class DeclRefExpr final
     setDependence(computeDependence(this, Context));
   }
 
-  /// Set type and compute and set dependence bits.
-  void setTypeFromBinding(QualType T, const ASTContext &Context) {
-    setType(T.getNonReferenceType());
-    setDependence(computeDependence(this, Context));
-  }
-
   static bool classof(const Stmt *T) {
     return T->getStmtClass() == DeclRefExprClass;
   }

clang/lib/AST/DeclCXX.cpp

@@ -3426,8 +3426,7 @@ VarDecl *BindingDecl::getHoldingVar() const {
 }
 
 llvm::ArrayRef<Expr *> BindingDecl::getBindingPackExprs() const {
-  if (!Binding)
-    return {};
+  assert(Binding && "expecting a pack expr");
   auto *RP = cast<ResolvedUnexpandedPackExpr>(Binding);
   return RP->getExprs();
 }

clang/lib/Sema/SemaDeclCXX.cpp

@@ -1570,25 +1570,13 @@ void Sema::CheckCompleteDecompositionDeclaration(DecompositionDecl *DD) {
   // If the type of the decomposition is dependent, then so is the type of
   // each binding.
   if (DecompType->isDependentType()) {
+    // Note that all of the types are still Null or PackExpansionType.
     for (auto *B : DD->bindings()) {
       // Do not overwrite any pack type.
       if (B->getType().isNull())
         B->setType(Context.DependentTy);
     }
     return;
-  } else {
-    // Set the types of the DeclRefExprs that point to nested pack bindings.
-    for (BindingDecl *B : DD->bindings()) {
-      if (B->isParameterPack()) {
-        for (Expr *E : B->getBindingPackExprs()) {
-          auto *DRE = cast<DeclRefExpr>(E);
-          auto *NestedB = cast<BindingDecl>(DRE->getDecl());
-          QualType T = NestedB->getType();
-          DRE->setTypeFromBinding(T, Context);
-        }
-        break;
-      }
-    }
   }
 
   DecompType = DecompType.getNonReferenceType();

clang/lib/Sema/SemaStmt.cpp

@@ -2671,9 +2671,8 @@ StmtResult Sema::BuildCXXForRangeStmt(
     if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
       if (auto *DD = dyn_cast<DecompositionDecl>(LoopVar))
         for (auto *Binding : DD->bindings()) {
-          if (!Binding->isParameterPack()) {
+          if (!Binding->isParameterPack())
             Binding->setType(Context.DependentTy);
-          }
         }
       LoopVar->setType(SubstAutoTypeDependent(LoopVar->getType()));
     }

clang/lib/Sema/SemaTemplateInstantiate.cpp

@@ -2494,9 +2494,8 @@ TemplateInstantiator::TransformDeclRefExpr(DeclRefExpr *E) {
     if (!BD)
       return ExprError();
     if (auto *RP =
-            dyn_cast_if_present<ResolvedUnexpandedPackExpr>(BD->getBinding())) {
+            dyn_cast_if_present<ResolvedUnexpandedPackExpr>(BD->getBinding()))
       return TransformResolvedUnexpandedPackExpr(RP);
-    }
   }
 
   return inherited::TransformDeclRefExpr(E);

clang/test/SemaCXX/cxx2c-binding-pack.cpp

@@ -161,7 +161,7 @@ void h(int (&arr)[N]) {
                             // b is a pack referring to the second and
                             // third elements, and c names the fourth element
   static_assert(sizeof...(b) == 2);
- auto& [...e] = arr;        // e is a pack referring to the four elements of the array
+  auto& [...e] = arr;        // e is a pack referring to the four elements of the array
   static_assert(sizeof...(e) == 4);
 }