diff options
Diffstat (limited to 'clang/lib/Sema/SemaTemplateDeduction.cpp')
| -rw-r--r-- | clang/lib/Sema/SemaTemplateDeduction.cpp | 39 |
1 files changed, 18 insertions, 21 deletions
diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp index 822ea12246a..521160d1ad2 100644 --- a/clang/lib/Sema/SemaTemplateDeduction.cpp +++ b/clang/lib/Sema/SemaTemplateDeduction.cpp @@ -860,34 +860,31 @@ public: /// Finish template argument deduction for a set of argument packs, /// producing the argument packs and checking for consistency with prior /// deductions. - Sema::TemplateDeductionResult - finish(bool TreatNoDeductionsAsNonDeduced = true) { + Sema::TemplateDeductionResult finish() { // Build argument packs for each of the parameter packs expanded by this // pack expansion. for (auto &Pack : Packs) { // Put back the old value for this pack. Deduced[Pack.Index] = Pack.Saved; - // If we are deducing the size of this pack even if we didn't deduce any - // values for it, then make sure we build a pack of the right size. - // FIXME: Should we always deduce the size, even if the pack appears in - // a non-deduced context? - if (!TreatNoDeductionsAsNonDeduced) - Pack.New.resize(PackElements); + // Always make sure the size of this pack is correct, even if we didn't + // deduce any values for it. + // + // FIXME: This isn't required by the normative wording, but substitution + // and post-substitution checking will always fail if the arity of any + // pack is not equal to the number of elements we processed. (Either that + // or something else has gone *very* wrong.) We're permitted to skip any + // hard errors from those follow-on steps by the intent (but not the + // wording) of C++ [temp.inst]p8: + // + // If the function selected by overload resolution can be determined + // without instantiating a class template definition, it is unspecified + // whether that instantiation actually takes place + Pack.New.resize(PackElements); // Build or find a new value for this pack. DeducedTemplateArgument NewPack; - if (PackElements && Pack.New.empty()) { - if (Pack.DeferredDeduction.isNull()) { - // We were not able to deduce anything for this parameter pack - // (because it only appeared in non-deduced contexts), so just - // restore the saved argument pack. - continue; - } - - NewPack = Pack.DeferredDeduction; - Pack.DeferredDeduction = TemplateArgument(); - } else if (Pack.New.empty()) { + if (Pack.New.empty()) { // If we deduced an empty argument pack, create it now. NewPack = DeducedTemplateArgument(TemplateArgument::getEmptyPack()); } else { @@ -2636,8 +2633,8 @@ static Sema::TemplateDeductionResult ConvertDeducedTemplateArguments( // be deduced to an empty sequence of template arguments. // FIXME: Where did the word "trailing" come from? if (Deduced[I].isNull() && Param->isTemplateParameterPack()) { - if (auto Result = PackDeductionScope(S, TemplateParams, Deduced, Info, I) - .finish(/*TreatNoDeductionsAsNonDeduced*/false)) + if (auto Result = + PackDeductionScope(S, TemplateParams, Deduced, Info, I).finish()) return Result; } |
