Index: include/clang/AST/Type.h =================================================================== --- include/clang/AST/Type.h +++ include/clang/AST/Type.h @@ -1642,6 +1642,25 @@ unsigned NumArgs; }; + class PackExpansionTypeBitfields { + friend class PackExpansionType; + + unsigned : NumTypeBits; + + /// The number of expansions that this pack expansion will + /// generate when substituted (+1), which is expected to be able to + /// hold at least 1024 according to [implimits]. However, as this limit + /// is somewhat easy to hit with template metaprogramming we'd prefer to + /// keep it as large as possible. At the moment it has been left as a + /// non-bitfield since this type safely fits in 64 bits as an unsigned, so + /// there is no reason to introduce the performance impact of a bitfield. + /// + /// This field will only have a non-zero value when some of the parameter + /// packs that occur within the pattern have been substituted but others + /// have not. + unsigned NumExpansions; + }; + union { TypeBitfields TypeBits; ArrayTypeBitfields ArrayTypeBits; @@ -1654,6 +1673,7 @@ TypeWithKeywordBitfields TypeWithKeywordBits; VectorTypeBitfields VectorTypeBits; TemplateSpecializationTypeBitfields TemplateSpecializationTypeBits; + PackExpansionTypeBitfields PackExpansionTypeBits; static_assert(sizeof(TypeBitfields) <= 8, "TypeBitfields is larger than 8 bytes!"); @@ -1678,6 +1698,8 @@ static_assert(sizeof(TemplateSpecializationTypeBitfields) <= 8, "TemplateSpecializationTypeBitfields is larger" " than 8 bytes!"); + static_assert(sizeof(PackExpansionTypeBitfields) <= 8, + "PackExpansionTypeBitfields is larger than 8 bytes"); }; private: @@ -5193,22 +5215,16 @@ /// The pattern of the pack expansion. QualType Pattern; - /// The number of expansions that this pack expansion will - /// generate when substituted (+1), or indicates that - /// - /// This field will only have a non-zero value when some of the parameter - /// packs that occur within the pattern have been substituted but others have - /// not. - unsigned NumExpansions; - PackExpansionType(QualType Pattern, QualType Canon, Optional NumExpansions) : Type(PackExpansion, Canon, /*Dependent=*/Pattern->isDependentType(), /*InstantiationDependent=*/true, /*VariablyModified=*/Pattern->isVariablyModifiedType(), /*ContainsUnexpandedParameterPack=*/false), - Pattern(Pattern), - NumExpansions(NumExpansions ? *NumExpansions + 1 : 0) {} + Pattern(Pattern) { + PackExpansionTypeBits.NumExpansions = + NumExpansions ? *NumExpansions + 1 : 0; + } public: /// Retrieve the pattern of this pack expansion, which is the @@ -5219,9 +5235,8 @@ /// Retrieve the number of expansions that this pack expansion will /// generate, if known. Optional getNumExpansions() const { - if (NumExpansions) - return NumExpansions - 1; - + if (PackExpansionTypeBits.NumExpansions) + return PackExpansionTypeBits.NumExpansions - 1; return None; }