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Implement the rest of C++0x [temp.deduct.type]p9, which specifies that 

the presence of a pack expansion anywhere except at the end of a
template-argument-list causes the entire template-argument-list to be
a non-deduced context.

llvm-svn: 122461
This commit is contained in:
Douglas Gregor 2010-12-23 01:24:45 +00:00
parent d5f66fcbac
commit d0ad2949fa
3 changed files with 83 additions and 4 deletions
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60
clang/lib/Sema/SemaTemplateDeduction.cpp
View File

@ -1059,6 +1059,33 @@ static TemplateParameter makeTemplateParameter(Decl *D) {
return TemplateParameter(cast<TemplateTemplateParmDecl>(D));
}
/// \brief Determine whether the given set of template arguments has a pack
/// expansion that is not the last template argument.
static bool hasPackExpansionBeforeEnd(const TemplateArgument *Args,
unsigned NumArgs) {
unsigned ArgIdx = 0;
while (ArgIdx < NumArgs) {
const TemplateArgument &Arg = Args[ArgIdx];
// Unwrap argument packs.
if (Args[ArgIdx].getKind() == TemplateArgument::Pack) {
Args = Arg.pack_begin();
NumArgs = Arg.pack_size();
ArgIdx = 0;
continue;
}
++ArgIdx;
if (ArgIdx == NumArgs)
return false;
if (Arg.isPackExpansion())
return true;
}
return false;
}
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
@ -1071,9 +1098,9 @@ DeduceTemplateArguments(Sema &S,
// If the template argument list of P contains a pack expansion that is not
// the last template argument, the entire template argument list is a
// non-deduced context.
// FIXME: Implement this.
if (hasPackExpansionBeforeEnd(Params, NumParams))
return Sema::TDK_Success;
// C++0x [temp.deduct.type]p9:
// If P has a form that contains <T> or <i>, then each argument Pi of the
// respective template argument list P is compared with the corresponding
@ -3052,6 +3079,15 @@ MarkUsedTemplateParameters(Sema &SemaRef, QualType T,
= cast<TemplateSpecializationType>(T);
MarkUsedTemplateParameters(SemaRef, Spec->getTemplateName(), OnlyDeduced,
Depth, Used);
// C++0x [temp.deduct.type]p9:
// If the template argument list of P contains a pack expansion that is not
// the last template argument, the entire template argument list is a
// non-deduced context.
if (OnlyDeduced &&
hasPackExpansionBeforeEnd(Spec->getArgs(), Spec->getNumArgs()))
break;
for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
MarkUsedTemplateParameters(SemaRef, Spec->getArg(I), OnlyDeduced, Depth,
Used);
@ -3078,6 +3114,15 @@ MarkUsedTemplateParameters(Sema &SemaRef, QualType T,
if (!OnlyDeduced)
MarkUsedTemplateParameters(SemaRef, Spec->getQualifier(),
OnlyDeduced, Depth, Used);
// C++0x [temp.deduct.type]p9:
// If the template argument list of P contains a pack expansion that is not
// the last template argument, the entire template argument list is a
// non-deduced context.
if (OnlyDeduced &&
hasPackExpansionBeforeEnd(Spec->getArgs(), Spec->getNumArgs()))
break;
for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
MarkUsedTemplateParameters(SemaRef, Spec->getArg(I), OnlyDeduced, Depth,
Used);
@ -3181,6 +3226,14 @@ void
Sema::MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs,
bool OnlyDeduced, unsigned Depth,
llvm::SmallVectorImpl<bool> &Used) {
// C++0x [temp.deduct.type]p9:
// If the template argument list of P contains a pack expansion that is not
// the last template argument, the entire template argument list is a
// non-deduced context.
if (OnlyDeduced &&
hasPackExpansionBeforeEnd(TemplateArgs.data(), TemplateArgs.size()))
return;
for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
::MarkUsedTemplateParameters(*this, TemplateArgs[I], OnlyDeduced,
Depth, Used);
@ -3196,6 +3249,7 @@ Sema::MarkDeducedTemplateParameters(FunctionTemplateDecl *FunctionTemplate,
Deduced.clear();
Deduced.resize(TemplateParams->size());
// FIXME: Variadic templates.
FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
::MarkUsedTemplateParameters(*this, Function->getParamDecl(I)->getType(),

2
clang/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.type/p2-0x.cpp
View File

@ -18,6 +18,6 @@ struct same_tuple<tuple<Types1...>, tuple<Types1...> > {
static const bool value = true;
};
//int same_tuple_check1[same_tuple<tuple<int, float>, tuple<int, double>>::value? -1 : 1];
int same_tuple_check1[same_tuple<tuple<int, float>, tuple<int, double>>::value? -1 : 1];
int same_tuple_check2[same_tuple<tuple<float, double>, tuple<float, double>>::value? 1 : -1];

25
clang/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.type/p9-0x.cpp Normal file
View File

@ -0,0 +1,25 @@
// RUN: %clang_cc1 -std=c++0x -fsyntax-only -verify %s
template<typename ...Types> struct tuple;
namespace PackExpansionNotAtEnd {
template<typename T, typename U>
struct tuple_same_with_int {
static const bool value = false;
};
template<typename ...Types>
struct tuple_same_with_int<tuple<Types...>, tuple<Types..., int>> {
static const bool value = true;
};
int tuple_same_with_int_1[tuple_same_with_int<tuple<int, float, double>,
tuple<int, float, double, int>
>::value? 1 : -1];
template<typename ... Types> struct UselessPartialSpec;
template<typename ... Types, // expected-note{{non-deducible template parameter 'Types'}}
typename Tail> // expected-note{{non-deducible template parameter 'Tail'}}
struct UselessPartialSpec<Types..., Tail>; // expected-warning{{class template partial specialization contains template parameters that can not be deduced; this partial specialization will never be used}}
}