[c++20] P0780R2: Support pack-expansion of init-captures.
This permits an init-capture to introduce a new pack:
template<typename ...T> auto x = [...a = T()] { /* a is a pack */ };
To support this, the mechanism for allowing ParmVarDecls to be packs has
been extended to support arbitrary local VarDecls.
llvm-svn: 361300
diff --git a/clang/lib/Sema/SemaTemplateVariadic.cpp b/clang/lib/Sema/SemaTemplateVariadic.cpp
index 8773f45..9b23624 100644
--- a/clang/lib/Sema/SemaTemplateVariadic.cpp
+++ b/clang/lib/Sema/SemaTemplateVariadic.cpp
@@ -39,11 +39,11 @@
unsigned DepthLimit = (unsigned)-1;
void addUnexpanded(NamedDecl *ND, SourceLocation Loc = SourceLocation()) {
- if (auto *PVD = dyn_cast<ParmVarDecl>(ND)) {
+ if (auto *VD = dyn_cast<VarDecl>(ND)) {
// For now, the only problematic case is a generic lambda's templated
// call operator, so we don't need to look for all the other ways we
// could have reached a dependent parameter pack.
- auto *FD = dyn_cast<FunctionDecl>(PVD->getDeclContext());
+ auto *FD = dyn_cast<FunctionDecl>(VD->getDeclContext());
auto *FTD = FD ? FD->getDescribedFunctionTemplate() : nullptr;
if (FTD && FTD->getTemplateParameters()->getDepth() >= DepthLimit)
return;
@@ -313,11 +313,11 @@
if (auto *LSI = dyn_cast<sema::LambdaScopeInfo>(Func)) {
if (N == FunctionScopes.size()) {
- for (auto &Param : Unexpanded) {
- auto *PD = dyn_cast_or_null<ParmVarDecl>(
- Param.first.dyn_cast<NamedDecl *>());
- if (PD && PD->getDeclContext() == LSI->CallOperator)
- LambdaParamPackReferences.push_back(Param);
+ for (auto &Pack : Unexpanded) {
+ auto *VD = dyn_cast_or_null<VarDecl>(
+ Pack.first.dyn_cast<NamedDecl *>());
+ if (VD && VD->getDeclContext() == LSI->CallOperator)
+ LambdaParamPackReferences.push_back(Pack);
}
}
@@ -586,11 +586,15 @@
QualType Sema::CheckPackExpansion(QualType Pattern, SourceRange PatternRange,
SourceLocation EllipsisLoc,
Optional<unsigned> NumExpansions) {
- // C++0x [temp.variadic]p5:
+ // C++11 [temp.variadic]p5:
// The pattern of a pack expansion shall name one or more
// parameter packs that are not expanded by a nested pack
// expansion.
- if (!Pattern->containsUnexpandedParameterPack()) {
+ //
+ // A pattern containing a deduced type can't occur "naturally" but arises in
+ // the desugaring of an init-capture pack.
+ if (!Pattern->containsUnexpandedParameterPack() &&
+ !Pattern->getContainedDeducedType()) {
Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
<< PatternRange;
return QualType();
@@ -641,7 +645,7 @@
// Compute the depth and index for this parameter pack.
unsigned Depth = 0, Index = 0;
IdentifierInfo *Name;
- bool IsFunctionParameterPack = false;
+ bool IsVarDeclPack = false;
if (const TemplateTypeParmType *TTP
= i->first.dyn_cast<const TemplateTypeParmType *>()) {
@@ -650,8 +654,8 @@
Name = TTP->getIdentifier();
} else {
NamedDecl *ND = i->first.get<NamedDecl *>();
- if (isa<ParmVarDecl>(ND))
- IsFunctionParameterPack = true;
+ if (isa<VarDecl>(ND))
+ IsVarDeclPack = true;
else
std::tie(Depth, Index) = getDepthAndIndex(ND);
@@ -660,7 +664,7 @@
// Determine the size of this argument pack.
unsigned NewPackSize;
- if (IsFunctionParameterPack) {
+ if (IsVarDeclPack) {
// Figure out whether we're instantiating to an argument pack or not.
typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack;
@@ -694,7 +698,7 @@
// Template argument deduction can extend the sequence of template
// arguments corresponding to a template parameter pack, even when the
// sequence contains explicitly specified template arguments.
- if (!IsFunctionParameterPack && CurrentInstantiationScope) {
+ if (!IsVarDeclPack && CurrentInstantiationScope) {
if (NamedDecl *PartialPack
= CurrentInstantiationScope->getPartiallySubstitutedPack()){
unsigned PartialDepth, PartialIndex;
@@ -778,8 +782,8 @@
Index = TTP->getIndex();
} else {
NamedDecl *ND = Unexpanded[I].first.get<NamedDecl *>();
- if (isa<ParmVarDecl>(ND)) {
- // Function parameter pack.
+ if (isa<VarDecl>(ND)) {
+ // Function parameter pack or init-capture pack.
typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack;
llvm::PointerUnion<Decl *, DeclArgumentPack *> *Instantiation
@@ -1084,7 +1088,7 @@
dyn_cast<SubstNonTypeTemplateParmPackExpr>(Arg.getAsExpr()))
Pack = Subst->getArgumentPack();
else if (auto *Subst = dyn_cast<FunctionParmPackExpr>(Arg.getAsExpr())) {
- for (ParmVarDecl *PD : *Subst)
+ for (VarDecl *PD : *Subst)
if (PD->isParameterPack())
return None;
return Subst->getNumExpansions();