Move unexpanded parameter handling into CapturingScopeInfo

clang/include/clang/AST/ComputeDependence.h

@@ -132,7 +132,8 @@ ExprDependence computeDependence(ArrayInitLoopExpr *E);
 ExprDependence computeDependence(ImplicitValueInitExpr *E);
 ExprDependence computeDependence(InitListExpr *E);
 ExprDependence computeDependence(ExtVectorElementExpr *E);
-ExprDependence computeDependence(BlockExpr *E);
+ExprDependence computeDependence(BlockExpr *E,
+                                 bool ContainsUnexpandedParameterPack);
 ExprDependence computeDependence(AsTypeExpr *E);
 ExprDependence computeDependence(DeclRefExpr *E, const ASTContext &Ctx);
 ExprDependence computeDependence(RecoveryExpr *E);

clang/include/clang/AST/Expr.h

@@ -6369,9 +6369,9 @@ class BlockExpr : public Expr {
 protected:
   BlockDecl *TheBlock;
 public:
-  BlockExpr(BlockDecl *BD, QualType ty)
+  BlockExpr(BlockDecl *BD, QualType ty, bool ContainsUnexpandedParameterPack)
       : Expr(BlockExprClass, ty, VK_PRValue, OK_Ordinary), TheBlock(BD) {
-    setDependence(computeDependence(this));
+    setDependence(computeDependence(this, ContainsUnexpandedParameterPack));
   }
 
   /// Build an empty block expression.

clang/include/clang/Sema/ScopeInfo.h

@@ -724,10 +724,16 @@ class CapturingScopeInfo : public FunctionScopeInfo {
   /// is deduced (e.g. a lambda or block with omitted return type).
   bool HasImplicitReturnType = false;
 
+  /// Whether this contains an unexpanded parameter pack.
+  bool ContainsUnexpandedParameterPack = false;
+
   /// ReturnType - The target type of return statements in this context,
   /// or null if unknown.
   QualType ReturnType;
 
+  /// Packs introduced by this, if any.
+  SmallVector<NamedDecl*, 4> LocalPacks;
+
   void addCapture(ValueDecl *Var, bool isBlock, bool isByref, bool isNested,
                   SourceLocation Loc, SourceLocation EllipsisLoc,
                   QualType CaptureType, bool Invalid) {
@@ -895,12 +901,6 @@ class LambdaScopeInfo final :
   /// Whether any of the capture expressions requires cleanups.
   CleanupInfo Cleanup;
 
-  /// Whether the lambda contains an unexpanded parameter pack.
-  bool ContainsUnexpandedParameterPack = false;
-
-  /// Packs introduced by this lambda, if any.
-  SmallVector<NamedDecl*, 4> LocalPacks;
-
   /// Source range covering the explicit template parameter list (if it exists).
   SourceRange ExplicitTemplateParamsRange;
 

clang/include/clang/Sema/Sema.h

@@ -750,10 +750,10 @@ class Sema final : public SemaBase {
   /// Retrieve the current block, if any.
   sema::BlockScopeInfo *getCurBlock();
 
-  /// Get the innermost lambda enclosing the current location, if any. This
-  /// looks through intervening non-lambda scopes such as local functions and
-  /// blocks.
-  sema::LambdaScopeInfo *getEnclosingLambda() const;
+  /// Get the innermost lambda or block enclosing the current location, if any.
+  /// This looks through intervening non-lambda, non-block scopes such as local
+  /// functions.
+  sema::CapturingScopeInfo *getEnclosingLambdaOrBlock() const;
 
   /// Retrieve the current lambda scope info, if any.
   /// \param IgnoreNonLambdaCapturingScope true if should find the top-most

clang/include/clang/Sema/Template.h

@@ -411,10 +411,10 @@ enum class TemplateSubstitutionKind : char {
     /// lookup will search our outer scope.
     bool CombineWithOuterScope;
 
-    /// Whether this scope is being used to instantiate a lambda expression,
-    /// in which case it should be reused for instantiating the lambda's
-    /// FunctionProtoType.
-    bool InstantiatingLambda = false;
+    /// Whether this scope is being used to instantiate a lambda or block
+    /// expression, in which case it should be reused for instantiating the
+    /// lambda's FunctionProtoType.
+    bool InstantiatingLambdaOrBlock = false;
 
     /// If non-NULL, the template parameter pack that has been
     /// partially substituted per C++0x [temp.arg.explicit]p9.
@@ -431,10 +431,10 @@ enum class TemplateSubstitutionKind : char {
 
   public:
     LocalInstantiationScope(Sema &SemaRef, bool CombineWithOuterScope = false,
-                            bool InstantiatingLambda = false)
+                            bool InstantiatingLambdaOrBlock = false)
         : SemaRef(SemaRef), Outer(SemaRef.CurrentInstantiationScope),
           CombineWithOuterScope(CombineWithOuterScope),
-          InstantiatingLambda(InstantiatingLambda) {
+          InstantiatingLambdaOrBlock(InstantiatingLambdaOrBlock) {
       SemaRef.CurrentInstantiationScope = this;
     }
 
@@ -561,8 +561,8 @@ enum class TemplateSubstitutionKind : char {
     /// Determine whether D is a pack expansion created in this scope.
     bool isLocalPackExpansion(const Decl *D);
 
-    /// Determine whether this scope is for instantiating a lambda.
-    bool isLambda() const { return InstantiatingLambda; }
+    /// Determine whether this scope is for instantiating a lambda or block.
+    bool isLambdaOrBlock() const { return InstantiatingLambdaOrBlock; }
   };
 
   class TemplateDeclInstantiator

clang/lib/AST/ComputeDependence.cpp

@@ -252,10 +252,13 @@ ExprDependence clang::computeDependence(ExtVectorElementExpr *E) {
   return E->getBase()->getDependence();
 }
 
-ExprDependence clang::computeDependence(BlockExpr *E) {
+ExprDependence clang::computeDependence(BlockExpr *E,
+                                        bool ContainsUnexpandedParameterPack) {
   auto D = toExprDependenceForImpliedType(E->getType()->getDependence());
   if (E->getBlockDecl()->isDependentContext())
     D |= ExprDependence::Instantiation;
+  if (ContainsUnexpandedParameterPack)
+    D |= ExprDependence::UnexpandedPack;
   return D;
 }
 

clang/lib/Sema/Sema.cpp

@@ -2382,18 +2382,19 @@ FunctionScopeInfo *Sema::getEnclosingFunction() const {
   return nullptr;
 }
 
-LambdaScopeInfo *Sema::getEnclosingLambda() const {
+CapturingScopeInfo *Sema::getEnclosingLambdaOrBlock() const {
   for (auto *Scope : llvm::reverse(FunctionScopes)) {
-    if (auto *LSI = dyn_cast<sema::LambdaScopeInfo>(Scope)) {
-      if (LSI->Lambda && !LSI->Lambda->Encloses(CurContext) &&
+    if (auto *CSI = dyn_cast<CapturingScopeInfo>(Scope)) {
+      auto *LSI = dyn_cast<LambdaScopeInfo>(CSI);
+      if (LSI && LSI->Lambda && !LSI->Lambda->Encloses(CurContext) &&
           LSI->AfterParameterList) {
         // We have switched contexts due to template instantiation.
         // FIXME: We should swap out the FunctionScopes during code synthesis
         // so that we don't need to check for this.
         assert(!CodeSynthesisContexts.empty());
         return nullptr;
       }
-      return LSI;
+      return CSI;
     }
   }
   return nullptr;

clang/lib/Sema/SemaDecl.cpp

@@ -15139,8 +15139,8 @@ ParmVarDecl *Sema::CheckParameter(DeclContext *DC, SourceLocation StartLoc,
   // we know that references to that pack must also be expanded within the
   // lambda scope.
   if (New->isParameterPack())
-    if (auto *LSI = getEnclosingLambda())
-      LSI->LocalPacks.push_back(New);
+    if (auto *CSI = getEnclosingLambdaOrBlock())
+      CSI->LocalPacks.push_back(New);
 
   if (New->getType().hasNonTrivialToPrimitiveDestructCUnion() ||
       New->getType().hasNonTrivialToPrimitiveCopyCUnion())

clang/lib/Sema/SemaExpr.cpp

@@ -16356,7 +16356,8 @@ ExprResult Sema::ActOnBlockStmtExpr(SourceLocation CaretLoc,
   AnalysisBasedWarnings::Policy WP = AnalysisWarnings.getDefaultPolicy();
   PoppedFunctionScopePtr ScopeRAII = PopFunctionScopeInfo(&WP, BD, BlockTy);
 
-  BlockExpr *Result = new (Context) BlockExpr(BD, BlockTy);
+  BlockExpr *Result = new (Context)
+      BlockExpr(BD, BlockTy, BSI->ContainsUnexpandedParameterPack);
 
   // If the block isn't obviously global, i.e. it captures anything at
   // all, then we need to do a few things in the surrounding context:

clang/lib/Sema/SemaLambda.cpp

@@ -2350,7 +2350,10 @@ ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
   Block->setBody(new (Context) CompoundStmt(ConvLocation));
 
   // Create the block literal expression.
-  Expr *BuildBlock = new (Context) BlockExpr(Block, Conv->getConversionType());
+  // TODO: Do we ever get here if we have unexpanded packs in the lambda???
+  Expr *BuildBlock =
+      new (Context) BlockExpr(Block, Conv->getConversionType(),
+                              /*ContainsUnexpandedParameterPack=*/false);
   ExprCleanupObjects.push_back(Block);
   Cleanup.setExprNeedsCleanups(true);
 

clang/lib/Sema/SemaTemplate.cpp

@@ -1010,8 +1010,8 @@ NamedDecl *Sema::ActOnTypeParameter(Scope *S, bool Typename,
   Param->setAccess(AS_public);
 
   if (Param->isParameterPack())
-    if (auto *LSI = getEnclosingLambda())
-      LSI->LocalPacks.push_back(Param);
+    if (auto *CSI = getEnclosingLambdaOrBlock())
+      CSI->LocalPacks.push_back(Param);
 
   if (ParamName) {
     maybeDiagnoseTemplateParameterShadow(*this, S, ParamNameLoc, ParamName);
@@ -1542,8 +1542,8 @@ NamedDecl *Sema::ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
     Param->setInvalidDecl();
 
   if (Param->isParameterPack())
-    if (auto *LSI = getEnclosingLambda())
-      LSI->LocalPacks.push_back(Param);
+    if (auto *CSI = getEnclosingLambdaOrBlock())
+      CSI->LocalPacks.push_back(Param);
 
   if (ParamName) {
     maybeDiagnoseTemplateParameterShadow(*this, S, D.getIdentifierLoc(),
@@ -1593,7 +1593,7 @@ NamedDecl *Sema::ActOnTemplateTemplateParameter(
   Param->setAccess(AS_public);
 
   if (Param->isParameterPack())
-    if (auto *LSI = getEnclosingLambda())
+    if (auto *LSI = getEnclosingLambdaOrBlock())
       LSI->LocalPacks.push_back(Param);
 
   // If the template template parameter has a name, then link the identifier

clang/lib/Sema/SemaTemplateInstantiate.cpp

@@ -1693,12 +1693,18 @@ namespace {
       if (SemaRef.RebuildingImmediateInvocation)
         return E;
       LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true,
-                                    /*InstantiatingLambda=*/true);
+                                    /*InstantiatingLambdaOrBlock=*/true);
       Sema::ConstraintEvalRAII<TemplateInstantiator> RAII(*this);
 
       return inherited::TransformLambdaExpr(E);
     }
 
+    ExprResult TransformBlockExpr(BlockExpr *E) {
+      LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true,
+                                    /*InstantiatingLambdaOrBlock=*/true);
+      return inherited::TransformBlockExpr(E);
+    }
+
     ExprResult RebuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
                                  LambdaScopeInfo *LSI) {
       CXXMethodDecl *MD = LSI->CallOperator;
@@ -2475,7 +2481,7 @@ QualType TemplateInstantiator::TransformFunctionProtoType(TypeLocBuilder &TLB,
                                  CXXRecordDecl *ThisContext,
                                  Qualifiers ThisTypeQuals,
                                  Fn TransformExceptionSpec) {
-  // If this is a lambda, the transformation MUST be done in the
+  // If this is a lambda or block, the transformation MUST be done in the
   // CurrentInstantiationScope since it introduces a mapping of
   // the original to the newly created transformed parameters.
   //
@@ -2484,7 +2490,7 @@ QualType TemplateInstantiator::TransformFunctionProtoType(TypeLocBuilder &TLB,
   // a second one.
   LocalInstantiationScope *Current = getSema().CurrentInstantiationScope;
   std::optional<LocalInstantiationScope> Scope;
-  if (!Current || !Current->isLambda())
+  if (!Current || !Current->isLambdaOrBlock())
     Scope.emplace(SemaRef, /*CombineWithOuterScope=*/true);
 
   return inherited::TransformFunctionProtoType(

clang/lib/Sema/SemaTemplateVariadic.cpp

@@ -36,7 +36,7 @@ namespace {
 
     SmallVectorImpl<UnexpandedParameterPack> &Unexpanded;
 
-    bool InLambda = false;
+    bool InLambdaOrBlock = false;
     unsigned DepthLimit = (unsigned)-1;
 
 #ifndef NDEBUG
@@ -140,7 +140,7 @@ namespace {
     /// do not contain unexpanded parameter packs.
     bool TraverseStmt(Stmt *S) {
       Expr *E = dyn_cast_or_null<Expr>(S);
-      if ((E && E->containsUnexpandedParameterPack()) || InLambda)
+      if ((E && E->containsUnexpandedParameterPack()) || InLambdaOrBlock)
         return inherited::TraverseStmt(S);
 
       return true;
@@ -149,7 +149,7 @@ namespace {
     /// Suppress traversal into types that do not contain
     /// unexpanded parameter packs.
     bool TraverseType(QualType T) {
-      if ((!T.isNull() && T->containsUnexpandedParameterPack()) || InLambda)
+      if ((!T.isNull() && T->containsUnexpandedParameterPack()) || InLambdaOrBlock)
         return inherited::TraverseType(T);
 
       return true;
@@ -160,7 +160,7 @@ namespace {
     bool TraverseTypeLoc(TypeLoc TL) {
       if ((!TL.getType().isNull() &&
            TL.getType()->containsUnexpandedParameterPack()) ||
-          InLambda)
+          InLambdaOrBlock)
         return inherited::TraverseTypeLoc(TL);
 
       return true;
@@ -262,20 +262,34 @@ namespace {
       if (!Lambda->containsUnexpandedParameterPack())
         return true;
 
-      bool WasInLambda = InLambda;
+      bool WasInLambdaOrBlock = InLambdaOrBlock;
       unsigned OldDepthLimit = DepthLimit;
 
-      InLambda = true;
+      InLambdaOrBlock = true;
       if (auto *TPL = Lambda->getTemplateParameterList())
         DepthLimit = TPL->getDepth();
 
       inherited::TraverseLambdaExpr(Lambda);
 
-      InLambda = WasInLambda;
+      InLambdaOrBlock = WasInLambdaOrBlock;
       DepthLimit = OldDepthLimit;
       return true;
     }
 
+    /// Analogously for blocks.
+    bool TraverseBlockExpr(BlockExpr* Block) {
+      if (!Block->containsUnexpandedParameterPack())
+        return true;
+
+      bool WasInLambdaOrBlock = InLambdaOrBlock;
+      InLambdaOrBlock = true;
+
+      inherited::TraverseBlockExpr(Block);
+
+      InLambdaOrBlock = WasInLambdaOrBlock;
+      return true;
+    }
+
     /// Suppress traversal within pack expansions in lambda captures.
     bool TraverseLambdaCapture(LambdaExpr *Lambda, const LambdaCapture *C,
                                Expr *Init) {
@@ -323,11 +337,11 @@ Sema::DiagnoseUnexpandedParameterPacks(SourceLocation Loc,
 
   // If we are within a lambda expression and referencing a pack that is not
   // declared within the lambda itself, that lambda contains an unexpanded
-  // parameter pack, and we are done.
+  // parameter pack, and we are done. Analogously for blocks.
   // FIXME: Store 'Unexpanded' on the lambda so we don't need to recompute it
   // later.
-  SmallVector<UnexpandedParameterPack, 4> LambdaParamPackReferences;
-  if (auto *LSI = getEnclosingLambda()) {
+  SmallVector<UnexpandedParameterPack, 4> ParamPackReferences;
+  if (sema::CapturingScopeInfo *CSI = getEnclosingLambdaOrBlock()) {
     for (auto &Pack : Unexpanded) {
       auto DeclaresThisPack = [&](NamedDecl *LocalPack) {
         if (auto *TTPT = Pack.first.dyn_cast<const TemplateTypeParmType *>()) {
@@ -336,11 +350,11 @@ Sema::DiagnoseUnexpandedParameterPacks(SourceLocation Loc,
         }
         return declaresSameEntity(Pack.first.get<NamedDecl *>(), LocalPack);
       };
-      if (llvm::any_of(LSI->LocalPacks, DeclaresThisPack))
-        LambdaParamPackReferences.push_back(Pack);
+      if (llvm::any_of(CSI->LocalPacks, DeclaresThisPack))
+        ParamPackReferences.push_back(Pack);
     }
 
-    if (LambdaParamPackReferences.empty()) {
+    if (ParamPackReferences.empty()) {
       // Construct in lambda only references packs declared outside the lambda.
       // That's OK for now, but the lambda itself is considered to contain an
       // unexpanded pack in this case, which will require expansion outside the
@@ -363,16 +377,16 @@ Sema::DiagnoseUnexpandedParameterPacks(SourceLocation Loc,
         }
         // Coumpound-statements outside the lambda are OK for now; we'll check
         // for those when we finish handling the lambda.
-        if (Func == LSI)
+        if (Func == CSI)
           break;
       }
 
       if (!EnclosingStmtExpr) {
-        LSI->ContainsUnexpandedParameterPack = true;
+        CSI->ContainsUnexpandedParameterPack = true;
         return false;
       }
     } else {
-      Unexpanded = LambdaParamPackReferences;
+      Unexpanded = ParamPackReferences;
     }
   }
 

clang/test/CXX/expr/expr.prim/expr.prim.lambda/blocks.mm

@@ -119,17 +119,16 @@ void call_with_lambda() {
 
     template<typename ... Args> static void f1()
     {
-      (void)^(Args args) { // expected-error{{block contains unexpanded parameter pack 'Args'}}
+      (void)^(Args args) { // expected-error{{expression contains unexpanded parameter pack 'Args'}}
       };
     }
 
     template<typename ... Args> static void f2()
     {
-      // FIXME: Allow this.
       f(
-        ^(Args args) // expected-error{{block contains unexpanded parameter pack 'Args'}}
+        ^(Args args)
         { }
-        ... // expected-error{{pack expansion does not contain any unexpanded parameter packs}}
+        ...
       );
     }