Implement C++0x [temp.arg.template]p3, which allows slightly fuzzy
matching of variadic template template parameters to template
arguments. This paragraph was the subject of ISO C++ committee
document N2555: Extending Variadic Template Template Parameters.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@123348 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 8d0462d..08384cc 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -3651,7 +3651,12 @@
}
// Check that both are parameter packs are neither are parameter packs.
- if (Old->isTemplateParameterPack() != New->isTemplateParameterPack()) {
+ // However, if we are matching a template template argument to a
+ // template template parameter, the template template parameter can have
+ // a parameter pack where the template template argument does not.
+ if (Old->isTemplateParameterPack() != New->isTemplateParameterPack() &&
+ !(Kind == Sema::TPL_TemplateTemplateArgumentMatch &&
+ Old->isTemplateParameterPack())) {
if (Complain) {
unsigned NextDiag = diag::err_template_parameter_pack_non_pack;
if (TemplateArgLoc.isValid()) {
@@ -3726,6 +3731,28 @@
return true;
}
+/// \brief Diagnose a known arity mismatch when comparing template argument
+/// lists.
+static
+void DiagnoseTemplateParameterListArityMismatch(Sema &S,
+ TemplateParameterList *New,
+ TemplateParameterList *Old,
+ Sema::TemplateParameterListEqualKind Kind,
+ SourceLocation TemplateArgLoc) {
+ unsigned NextDiag = diag::err_template_param_list_different_arity;
+ if (TemplateArgLoc.isValid()) {
+ S.Diag(TemplateArgLoc, diag::err_template_arg_template_params_mismatch);
+ NextDiag = diag::note_template_param_list_different_arity;
+ }
+ S.Diag(New->getTemplateLoc(), NextDiag)
+ << (New->size() > Old->size())
+ << (Kind != Sema::TPL_TemplateMatch)
+ << SourceRange(New->getTemplateLoc(), New->getRAngleLoc());
+ S.Diag(Old->getTemplateLoc(), diag::note_template_prev_declaration)
+ << (Kind != Sema::TPL_TemplateMatch)
+ << SourceRange(Old->getTemplateLoc(), Old->getRAngleLoc());
+}
+
/// \brief Determine whether the given template parameter lists are
/// equivalent.
///
@@ -3755,21 +3782,10 @@
bool Complain,
TemplateParameterListEqualKind Kind,
SourceLocation TemplateArgLoc) {
- if (Old->size() != New->size()) {
- if (Complain) {
- unsigned NextDiag = diag::err_template_param_list_different_arity;
- if (TemplateArgLoc.isValid()) {
- Diag(TemplateArgLoc, diag::err_template_arg_template_params_mismatch);
- NextDiag = diag::note_template_param_list_different_arity;
- }
- Diag(New->getTemplateLoc(), NextDiag)
- << (New->size() > Old->size())
- << (Kind != TPL_TemplateMatch)
- << SourceRange(New->getTemplateLoc(), New->getRAngleLoc());
- Diag(Old->getTemplateLoc(), diag::note_template_prev_declaration)
- << (Kind != TPL_TemplateMatch)
- << SourceRange(Old->getTemplateLoc(), Old->getRAngleLoc());
- }
+ if (Old->size() != New->size() && Kind != TPL_TemplateTemplateArgumentMatch) {
+ if (Complain)
+ DiagnoseTemplateParameterListArityMismatch(*this, New, Old, Kind,
+ TemplateArgLoc);
return false;
}
@@ -3779,15 +3795,52 @@
// when each of the template parameters in the template-parameter-list of
// the template-argument’s corresponding class template or template alias
// (call it A) matches the corresponding template parameter in the
- // template-parameter-list of P.
+ // template-parameter-list of P. [...]
+ TemplateParameterList::iterator NewParm = New->begin();
+ TemplateParameterList::iterator NewParmEnd = New->end();
for (TemplateParameterList::iterator OldParm = Old->begin(),
- OldParmEnd = Old->end(), NewParm = New->begin();
- OldParm != OldParmEnd; ++OldParm, ++NewParm) {
- if (!MatchTemplateParameterKind(*this, *NewParm, *OldParm, Complain,
- Kind, TemplateArgLoc))
- return false;
+ OldParmEnd = Old->end();
+ OldParm != OldParmEnd; ++OldParm) {
+ if (!(*OldParm)->isTemplateParameterPack()) {
+ if (NewParm == NewParmEnd) {
+ if (Complain)
+ DiagnoseTemplateParameterListArityMismatch(*this, New, Old, Kind,
+ TemplateArgLoc);
+
+ return false;
+ }
+
+ if (!MatchTemplateParameterKind(*this, *NewParm, *OldParm, Complain,
+ Kind, TemplateArgLoc))
+ return false;
+
+ ++NewParm;
+ continue;
+ }
+
+ // C++0x [temp.arg.template]p3:
+ // [...] When P’s template- parameter-list contains a template parameter
+ // pack (14.5.3), the template parameter pack will match zero or more
+ // template parameters or template parameter packs in the
+ // template-parameter-list of A with the same type and form as the
+ // template parameter pack in P (ignoring whether those template
+ // parameters are template parameter packs).
+ for (; NewParm != NewParmEnd; ++NewParm) {
+ if (!MatchTemplateParameterKind(*this, *NewParm, *OldParm, Complain,
+ Kind, TemplateArgLoc))
+ return false;
+ }
}
-
+
+ // Make sure we exhausted all of the arguments.
+ if (NewParm != NewParmEnd) {
+ if (Complain)
+ DiagnoseTemplateParameterListArityMismatch(*this, New, Old, Kind,
+ TemplateArgLoc);
+
+ return false;
+ }
+
return true;
}