Implement the sizeof...(pack) expression to compute the length of a
parameter pack.
Note that we're missing proper libclang support for the new
SizeOfPackExpr expression node.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@122813 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaTemplateVariadic.cpp b/lib/Sema/SemaTemplateVariadic.cpp
index 92df1fd..4e01ec2 100644
--- a/lib/Sema/SemaTemplateVariadic.cpp
+++ b/lib/Sema/SemaTemplateVariadic.cpp
@@ -10,6 +10,7 @@
//===----------------------------------------------------------------------===/
#include "clang/Sema/Sema.h"
+#include "clang/Sema/Lookup.h"
#include "clang/Sema/ParsedTemplate.h"
#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/Template.h"
@@ -533,3 +534,71 @@
return false;
}
+
+/// \brief Called when an expression computing the size of a parameter pack
+/// is parsed.
+///
+/// \code
+/// template<typename ...Types> struct count {
+/// static const unsigned value = sizeof...(Types);
+/// };
+/// \endcode
+///
+//
+/// \param OpLoc The location of the "sizeof" keyword.
+/// \param Name The name of the parameter pack whose size will be determined.
+/// \param NameLoc The source location of the name of the parameter pack.
+/// \param RParenLoc The location of the closing parentheses.
+ExprResult Sema::ActOnSizeofParameterPackExpr(Scope *S,
+ SourceLocation OpLoc,
+ IdentifierInfo &Name,
+ SourceLocation NameLoc,
+ SourceLocation RParenLoc) {
+ // C++0x [expr.sizeof]p5:
+ // The identifier in a sizeof... expression shall name a parameter pack.
+
+ LookupResult R(*this, &Name, NameLoc, LookupOrdinaryName);
+ LookupName(R, S);
+
+ NamedDecl *ParameterPack = 0;
+ switch (R.getResultKind()) {
+ case LookupResult::Found:
+ ParameterPack = R.getFoundDecl();
+ break;
+
+ case LookupResult::NotFound:
+ case LookupResult::NotFoundInCurrentInstantiation:
+ if (DeclarationName CorrectedName = CorrectTypo(R, S, 0, 0, false,
+ CTC_NoKeywords)) {
+ // FIXME: Variadic templates function parameter packs.
+ if (NamedDecl *CorrectedResult = R.getAsSingle<NamedDecl>())
+ if (CorrectedResult->isTemplateParameterPack()) {
+ ParameterPack = CorrectedResult;
+ Diag(NameLoc, diag::err_sizeof_pack_no_pack_name_suggest)
+ << &Name << CorrectedName
+ << FixItHint::CreateReplacement(NameLoc,
+ CorrectedName.getAsString());
+ Diag(ParameterPack->getLocation(), diag::note_parameter_pack_here)
+ << CorrectedName;
+ }
+ }
+
+ case LookupResult::FoundOverloaded:
+ case LookupResult::FoundUnresolvedValue:
+ break;
+
+ case LookupResult::Ambiguous:
+ DiagnoseAmbiguousLookup(R);
+ return ExprError();
+ }
+
+ // FIXME: Variadic templates function parameter packs.
+ if (!ParameterPack || !ParameterPack->isTemplateParameterPack()) {
+ Diag(NameLoc, diag::err_sizeof_pack_no_pack_name)
+ << &Name;
+ return ExprError();
+ }
+
+ return new (Context) SizeOfPackExpr(Context.getSizeType(), OpLoc,
+ ParameterPack, NameLoc, RParenLoc);
+}
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index c38902a..27fbf93 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -1913,6 +1913,16 @@
return SemaRef.BuildCXXNoexceptExpr(Range.getBegin(), Arg, Range.getEnd());
}
+ /// \brief Build a new expression to compute the length of a parameter pack.
+ ExprResult RebuildSizeOfPackExpr(SourceLocation OperatorLoc, NamedDecl *Pack,
+ SourceLocation PackLoc,
+ SourceLocation RParenLoc,
+ unsigned Length) {
+ return new (SemaRef.Context) SizeOfPackExpr(SemaRef.Context.getSizeType(),
+ OperatorLoc, Pack, PackLoc,
+ RParenLoc, Length);
+ }
+
/// \brief Build a new Objective-C @encode expression.
///
/// By default, performs semantic analysis to build the new expression.
@@ -6499,7 +6509,36 @@
llvm_unreachable("pack expansion expression in unhandled context");
return ExprError();
}
+
+template<typename Derived>
+ExprResult
+TreeTransform<Derived>::TransformSizeOfPackExpr(SizeOfPackExpr *E) {
+ // If E is not value-dependent, then nothing will change when we transform it.
+ // Note: This is an instantiation-centric view.
+ if (!E->isValueDependent())
+ return SemaRef.Owned(E);
+
+ // Note: None of the implementations of TryExpandParameterPacks can ever
+ // produce a diagnostic when given only a single unexpanded parameter pack,
+ // so
+ UnexpandedParameterPack Unexpanded(E->getPack(), E->getPackLoc());
+ bool ShouldExpand = false;
+ unsigned NumExpansions = 0;
+ if (getDerived().TryExpandParameterPacks(E->getOperatorLoc(), E->getPackLoc(),
+ &Unexpanded, 1,
+ ShouldExpand, NumExpansions))
+ return ExprError();
+ if (!ShouldExpand)
+ return SemaRef.Owned(E);
+
+ // We now know the length of the parameter pack, so build a new expression
+ // that stores that length.
+ return getDerived().RebuildSizeOfPackExpr(E->getOperatorLoc(), E->getPack(),
+ E->getPackLoc(), E->getRParenLoc(),
+ NumExpansions);
+}
+
template<typename Derived>
ExprResult
TreeTransform<Derived>::TransformObjCStringLiteral(ObjCStringLiteral *E) {