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[Sema] Disallow ambigious base classes in template argument deduction 

Fixes PR28195.

Differential revision: http://reviews.llvm.org/D21653

llvm-svn: 274077
This commit is contained in:
Erik Pilkington 2016-06-28 23:05:09 +00:00
parent 2b2b1a9200
commit 6a16ac0ed7
2 changed files with 44 additions and 22 deletions
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53
clang/lib/Sema/SemaTemplateDeduction.cpp
View File

@ -103,12 +103,12 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
bool PartialOrdering = false);
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
const TemplateArgument *Params, unsigned NumParams,
const TemplateArgument *Args, unsigned NumArgs,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced);
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool NumberOfArgumentsMustMatch);
/// \brief If the given expression is of a form that permits the deduction
/// of a non-type template parameter, return the declaration of that
@ -453,10 +453,10 @@ DeduceTemplateArguments(Sema &S,
// Perform template argument deduction on each template
// argument. Ignore any missing/extra arguments, since they could be
// filled in by default arguments.
return DeduceTemplateArguments(S, TemplateParams,
Param->getArgs(), Param->getNumArgs(),
SpecArg->getArgs(), SpecArg->getNumArgs(),
Info, Deduced);
return DeduceTemplateArguments(S, TemplateParams, Param->getArgs(),
Param->getNumArgs(), SpecArg->getArgs(),
SpecArg->getNumArgs(), Info, Deduced,
/*NumberOfArgumentsMustMatch=*/false);
}
// If the argument type is a class template specialization, we
@ -487,11 +487,10 @@ DeduceTemplateArguments(Sema &S,
return Result;
// Perform template argument deduction for the template arguments.
return DeduceTemplateArguments(S, TemplateParams,
Param->getArgs(), Param->getNumArgs(),
SpecArg->getTemplateArgs().data(),
SpecArg->getTemplateArgs().size(),
Info, Deduced);
return DeduceTemplateArguments(
S, TemplateParams, Param->getArgs(), Param->getNumArgs(),
SpecArg->getTemplateArgs().data(), SpecArg->getTemplateArgs().size(),
Info, Deduced, /*NumberOfArgumentsMustMatch=*/true);
}
/// \brief Determines whether the given type is an opaque type that
@ -1461,6 +1460,7 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
SmallVector<const RecordType *, 8> ToVisit;
ToVisit.push_back(RecordT);
bool Successful = false;
SmallVector<DeducedTemplateArgument, 8> SuccessfulDeduced;
while (!ToVisit.empty()) {
// Retrieve the next class in the inheritance hierarchy.
const RecordType *NextT = ToVisit.pop_back_val();
@ -1481,14 +1481,20 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
// note that we had some success. Otherwise, ignore any deductions
// from this base class.
if (BaseResult == Sema::TDK_Success) {
// If we've already seen some success, then deduction fails due to
// an ambiguity (temp.deduct.call p5).
if (Successful)
return Sema::TDK_MiscellaneousDeductionFailure;
Successful = true;
DeducedOrig.clear();
DeducedOrig.append(Deduced.begin(), Deduced.end());
std::swap(SuccessfulDeduced, Deduced);
Info.Param = BaseInfo.Param;
Info.FirstArg = BaseInfo.FirstArg;
Info.SecondArg = BaseInfo.SecondArg;
} else
Deduced = DeducedOrig;
}
Deduced = DeducedOrig;
}
// Visit base classes
@ -1500,8 +1506,10 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
}
}
if (Successful)
if (Successful) {
std::swap(SuccessfulDeduced, Deduced);
return Sema::TDK_Success;
}
return Result;
}
@ -1825,12 +1833,12 @@ static bool hasPackExpansionBeforeEnd(const TemplateArgument *Args,
}
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
const TemplateArgument *Params, unsigned NumParams,
const TemplateArgument *Args, unsigned NumArgs,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool NumberOfArgumentsMustMatch) {
// 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
@ -1850,7 +1858,8 @@ DeduceTemplateArguments(Sema &S,
// Check whether we have enough arguments.
if (!hasTemplateArgumentForDeduction(Args, ArgIdx, NumArgs))
return Sema::TDK_Success;
return NumberOfArgumentsMustMatch ? Sema::TDK_TooFewArguments
: Sema::TDK_Success;
if (Args[ArgIdx].isPackExpansion()) {
// FIXME: We follow the logic of C++0x [temp.deduct.type]p22 here,
@ -1921,7 +1930,7 @@ DeduceTemplateArguments(Sema &S,
return DeduceTemplateArguments(S, TemplateParams,
ParamList.data(), ParamList.size(),
ArgList.data(), ArgList.size(),
Info, Deduced);
Info, Deduced, false);
}
/// \brief Determine whether two template arguments are the same.

13
clang/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p3.cpp
View File

@ -160,3 +160,16 @@ int fn() {
}
}
namespace PR28195 {
template<int N> struct B {};
struct D : B<0>, B<1> {};
template<int N> int callee(B<N>); // expected-note{{failed template argument deduction}}
int caller() {
callee(D()); // expected-error{{no matching function}}
}
}