Implement partial ordering of class template partial specializations
and function templates that contain variadic templates. This involves
three small-ish changes:
(1) When transforming a pack expansion, if the transformed argument
still contains unexpanded parameter packs, build a pack
expansion. This can happen during the substitution that occurs into
class template partial specialiation template arguments during
partial ordering.
(2) When performing template argument deduction where the argument
is a pack expansion, match against the pattern of that pack
expansion.
(3) When performing template argument deduction against a non-pack
parameter, or a non-expansion template argument, deduction fails if
the argument itself is a pack expansion (C++0x
[temp.deduct.type]p22).
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@123279 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaTemplateDeduction.cpp b/lib/Sema/SemaTemplateDeduction.cpp
index 6d0db4a..dcc1ada 100644
--- a/lib/Sema/SemaTemplateDeduction.cpp
+++ b/lib/Sema/SemaTemplateDeduction.cpp
@@ -80,7 +80,7 @@
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
const TemplateArgument &Param,
- const TemplateArgument &Arg,
+ TemplateArgument Arg,
TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<DeducedTemplateArgument> &Deduced);
@@ -677,6 +677,13 @@
if (ArgIdx >= NumArgs)
return Sema::TDK_NonDeducedMismatch;
+ if (isa<PackExpansionType>(Args[ArgIdx])) {
+ // C++0x [temp.deduct.type]p22:
+ // If the original function parameter associated with A is a function
+ // parameter pack and the function parameter associated with P is not
+ // a function parameter pack, then template argument deduction fails.
+ return Sema::TDK_NonDeducedMismatch;
+ }
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(S, TemplateParams,
@@ -814,6 +821,12 @@
QualType Param = S.Context.getCanonicalType(ParamIn);
QualType Arg = S.Context.getCanonicalType(ArgIn);
+ // If the argument type is a pack expansion, look at its pattern.
+ // This isn't explicitly called out
+ if (const PackExpansionType *ArgExpansion
+ = dyn_cast<PackExpansionType>(Arg))
+ Arg = ArgExpansion->getPattern();
+
if (PartialOrdering) {
// C++0x [temp.deduct.partial]p5:
// Before the partial ordering is done, certain transformations are
@@ -1273,9 +1286,15 @@
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
const TemplateArgument &Param,
- const TemplateArgument &Arg,
+ TemplateArgument Arg,
TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
+ // If the template argument is a pack expansion, perform template argument
+ // deduction against the pattern of that expansion. This only occurs during
+ // partial ordering.
+ if (Arg.isPackExpansion())
+ Arg = Arg.getPackExpansionPattern();
+
switch (Param.getKind()) {
case TemplateArgument::Null:
assert(false && "Null template argument in parameter list");
@@ -1448,11 +1467,17 @@
return NumberOfArgumentsMustMatch? Sema::TDK_NonDeducedMismatch
: Sema::TDK_Success;
+ if (Args[ArgIdx].isPackExpansion()) {
+ // FIXME: We follow the logic of C++0x [temp.deduct.type]p22 here,
+ // but applied to pack expansions that are template arguments.
+ return Sema::TDK_NonDeducedMismatch;
+ }
+
// Perform deduction for this Pi/Ai pair.
if (Sema::TemplateDeductionResult Result
- = DeduceTemplateArguments(S, TemplateParams,
- Params[ParamIdx], Args[ArgIdx],
- Info, Deduced))
+ = DeduceTemplateArguments(S, TemplateParams,
+ Params[ParamIdx], Args[ArgIdx],
+ Info, Deduced))
return Result;
// Move to the next argument.
@@ -1792,7 +1817,7 @@
return Sema::TDK_SubstitutionFailure;
}
}
-
+
// Form the template argument list from the deduced template arguments.
TemplateArgumentList *DeducedArgumentList
= TemplateArgumentList::CreateCopy(S.Context, Builder.data(),