:orphan: .. _ABI: .. highlight:: none Mangling -------- :: mangled-name ::= '$s' global // Swift stable mangling mangled-name ::= '@__swiftmacro_' global // Swift mangling for filenames mangled-name ::= '_T0' global // Swift 4.0 mangled-name ::= '$S' global // Swift 4.2 mangled-name ::= '$e' global // Embedded Swift (unstable) All Swift-mangled names begin with a common prefix. Since Swift 4.0, the compiler has used variations of the mangling described in this document, though pre-stable versions may not exactly conform to this description. By using distinct prefixes, tools can attempt to accommodate bugs and version variations in pre-stable versions of Swift. The basic mangling scheme is a list of 'operators' where the operators are structured in a post-fix order. For example the mangling may start with an identifier but only later in the mangling a type-like operator defines how this identifier has to be interpreted:: 4Test3FooC // The trailing 'C' says that 'Foo' is a class in module 'Test' Operators are either identifiers or a sequence of one or more characters, like ``C`` for class. All operators share the same name-space. Important operators are a single character, which means that no other operator may start with the same character. Some less important operators are longer and may also contain one or more natural numbers. But it's always important that the demangler can identify the end (the last character) of an operator. For example, it's not possible to determine the last character if there are two operators ``M`` and ``Ma``: ``a`` could belong to ``M`` or it could be the first character of the next operator. The intention of the post-fix order is to optimize for common pre-fixes. Regardless, if it's the mangling for a metatype or a function in a module, the mangled name will start with the module name (after the ``_S``). In the following, productions which are only _part_ of an operator, are named with uppercase letters. Symbolic references ~~~~~~~~~~~~~~~~~~~ The Swift compiler emits mangled names into binary images to encode references to types for runtime instantiation and reflection. In a binary, these mangled names may embed pointers to runtime data structures in order to more efficiently represent locally-defined types. We call these pointers **symbolic references**. These references will be introduced by a control character in the range `\x01` ... `\x1F`, which indicates the kind of symbolic reference, followed by some number of arbitrary bytes *which may include null bytes*. Code that processes mangled names out of Swift binaries needs to be aware of symbolic references in order to properly terminate strings; a null terminator may be part of a symbolic reference. :: symbolic-reference ::= [\x01-\x17] .{4} // Relative symbolic reference #if sizeof(void*) == 8 symbolic-reference ::= [\x18-\x1F] .{8} // Absolute symbolic reference for 64-bit pointers #elif sizeof(void*) == 4 symbolic-reference ::= [\x18-\x1F] .{4} // Absolute symbolic reference for 32-bit pointers #endif Symbolic references are only valid in compiler-emitted metadata structures and must only appear in read-only parts of a binary image. APIs and tools that interpret Swift mangled names from potentially uncontrolled inputs must refuse to interpret symbolic references. The following symbolic reference kinds are currently implemented: :: #if SWIFT_RUNTIME_VERSION < 5.1 {any-generic-type, protocol} ::= '\x01' .{4} // Reference points directly to context descriptor {any-generic-type, protocol} ::= '\x02' .{4} // Reference points indirectly to context descriptor #else {any-generic-type, protocol, opaque-type-decl-name} ::= '\x01' .{4} // Reference points directly to context descriptor {any-generic-type, protocol, opaque-type-decl-name} ::= '\x02' .{4} // Reference points indirectly to context descriptor #endif // The grammatical role of the symbolic reference is determined by the // kind of context descriptor referenced protocol-conformance-ref ::= '\x03' .{4} // Reference points directly to protocol conformance descriptor (NOT IMPLEMENTED) protocol-conformance-ref ::= '\x04' .{4} // Reference points indirectly to protocol conformance descriptor (NOT IMPLEMENTED) dependent-associated-conformance ::= '\x05' .{4} // Reference points directly to associated conformance descriptor (NOT IMPLEMENTED) dependent-associated-conformance ::= '\x06' .{4} // Reference points indirectly to associated conformance descriptor (NOT IMPLEMENTED) associated-conformance-access-function ::= '\x07' .{4} // Reference points directly to associated conformance access function relative to the protocol associated-conformance-access-function ::= '\x08' .{4} // Reference points directly to associated conformance access function relative to the conforming type // keypaths only in Swift 5.0, generalized in Swift 5.1 #if SWIFT_RUNTIME_VERSION >= 5.1 metadata-access-function ::= '\x09' .{4} // Reference points directly to metadata access function that can be invoked to produce referenced object #endif #if SWIFT_RUNTIME_VERISON >= 5.7 symbolic-extended-existential-type-shape ::= '\x0A' .{4} // Reference points directly to an ExtendedExistentialTypeShape symbolic-extended-existential-type-shape ::= '\x0B' .{4} // Reference points directly to a NonUniqueExtendedExistentialTypeShape #endif #if SWIFT_RUNTIME_VERSION >= 5.TBD objective-c-protocol-relative-reference ::= '\x0C' .{4} // Reference points directly to a objective-c protcol reference #endif A mangled name may also include ``\xFF`` bytes, which are only used for alignment padding. They do not affect what the mangled name references and can be skipped over and ignored. Globals ~~~~~~~ :: global ::= type 'N' // type metadata (address point) // -- type starts with [BCOSTV] global ::= type 'Mf' // 'full' type metadata (start of object) global ::= type 'MP' // type metadata pattern global ::= type 'Ma' // type metadata access function global ::= type 'ML' // type metadata lazy cache variable global ::= nominal-type 'Mr' // generic type completion function global ::= nominal-type 'Mi' // generic type instantiation function global ::= nominal-type 'MI' // generic type instantiation cache global ::= nominal-type 'Ml' // in-place type initialization cache global ::= nominal-type 'Mm' // class metaclass global ::= nominal-type 'Mn' // nominal type descriptor #if SWIFT_RUNTIME_VERSION >= 5.1 global ::= opaque-type-decl-name 'MQ' // opaque type descriptor -- added in Swift 5.1 #endif global ::= nominal-type 'Mu' // class method lookup function global ::= nominal-type 'MU' // ObjC metadata update callback function global ::= nominal-type 'Ms' // ObjC resilient class stub global ::= nominal-type 'Mt' // Full ObjC resilient class stub (private) global ::= module 'MXM' // module descriptor global ::= context 'MXE' // extension descriptor global ::= context 'MXX' // anonymous context descriptor global ::= context identifier 'MXY' // anonymous context descriptor global ::= type assoc-type-list 'MXA' // generic parameter ref (HISTORICAL) global ::= protocol 'Mp' // protocol descriptor global ::= protocol 'Hr' // protocol descriptor runtime record global ::= nominal-type 'Hn' // nominal type descriptor runtime record #if SWIFT_RUNTIME_VERSION >= 5.1 global ::= opaque-type-decl-name 'Ho' // opaque type descriptor runtime record #endif global ::= protocol-conformance 'Hc' // protocol conformance runtime record global ::= global 'HF' // accessible function runtime record global ::= nominal-type 'Mo' // class metadata immediate member base offset global ::= type 'MF' // metadata for remote mirrors: field descriptor global ::= type 'MB' // metadata for remote mirrors: builtin type descriptor global ::= protocol-conformance 'MA' // metadata for remote mirrors: associated type descriptor global ::= nominal-type 'MC' // metadata for remote mirrors: superclass descriptor global ::= mangled-name 'TA' // partial application forwarder global ::= mangled-name 'Ta' // ObjC partial application forwarder global ::= mangled-name 'TQ' index // Async await continuation partial function global ::= mangled-name 'TY' index // Async suspend continuation partial function global ::= mangled-name 'TwS' // #_hasSymbol query function global ::= type 'w' VALUE-WITNESS-KIND // value witness global ::= protocol 'MS' // protocol self-conformance descriptor global ::= protocol 'WS' // protocol self-conformance witness table global ::= protocol-conformance 'Mc' // protocol conformance descriptor global ::= protocol-conformance 'WP' // protocol witness table global ::= protocol-conformance 'Wa' // protocol witness table accessor (HISTORICAL) global ::= protocol-conformance 'WG' // generic protocol witness table (HISTORICAL) global ::= protocol-conformance 'Wp' // protocol witness table pattern global ::= protocol-conformance 'Wr' // resilient witness table (HISTORICAL) global ::= protocol-conformance 'WI' // generic protocol witness table instantiation function global ::= type protocol-conformance 'WL' // lazy protocol witness table cache variable global ::= protocol-conformance identifier 'Wt' // associated type metadata accessor (HISTORICAL) global ::= protocol-conformance assoc-type-list protocol 'WT' // associated type witness table accessor global ::= protocol-conformance protocol 'Wb' // base protocol witness table accessor global ::= type protocol-conformance 'Wl' // lazy protocol witness table accessor global ::= global generic-signature? 'WJ' DIFFERENTIABILITY-KIND INDEX-SUBSET 'p' INDEX-SUBSET 'r' // differentiability witness global ::= type 'WV' // value witness table global ::= entity 'Wvd' // field offset global ::= entity 'WC' // resilient enum tag index global ::= global 'MK' // instantiation cache associated with global global ::= global 'MJ' // noncanonical specialized generic type metadata instantiation cache associated with global global ::= global 'MN' // noncanonical specialized generic type metadata for global global ::= global 'Mz' // canonical specialized generic type metadata caching token global ::= global 'Mq' // global with a uniquing prefix #if SWIFT_RUNTIME_VERSION >= 5.4 global ::= context (decl-name '_')+ 'WZ' // global variable one-time initialization function global ::= context (decl-name '_')+ 'Wz' // global variable one-time initialization token #endif A direct symbol resolves directly to the address of an object. An indirect symbol resolves to the address of a pointer to the object. They are distinct manglings to make a certain class of bugs immediately obvious. The terminology is slightly overloaded when discussing offsets. A direct offset resolves to a variable holding the true offset. An indirect offset resolves to a variable holding an offset to be applied to type metadata to get the address of the true offset. (Offset variables are required when the object being accessed lies within a resilient structure. When the layout of the object may depend on generic arguments, these offsets must be kept in metadata. Indirect field offsets are therefore required when accessing fields in generic types where the metadata itself has unknown layout.) :: global ::= global 'Tj' // resilient method dispatch thunk global ::= global 'Tq' // method descriptor global ::= global 'TO' // ObjC-as-swift thunk global ::= global 'To' // swift-as-ObjC thunk global ::= global 'TD' // dynamic dispatch thunk global ::= global 'Td' // direct method reference thunk global ::= global 'TE' // distributed actor thunk global ::= global 'TF' // distributed method accessor global ::= global 'TI' // implementation of a dynamic_replaceable function global ::= global 'Tu' // async function pointer of a function global ::= global 'TX' // function pointer of a dynamic_replaceable function global ::= global 'Twb' // back deployment thunk global ::= global 'TwB' // back deployment fallback function global ::= global 'Twc' // coro function pointer of a function global ::= global 'Twd' // default override of a function global ::= entity entity 'TV' // vtable override thunk, derived followed by base global ::= type label-list? 'D' // type mangling for the debugger with label list for function types. global ::= type 'TC' // continuation prototype (not actually used for real symbols) global ::= protocol-conformance entity 'TW' // protocol witness thunk global ::= entity 'TS' // protocol self-conformance witness thunk global ::= context identifier identifier 'TB' // property behavior initializer thunk (not used currently) global ::= context identifier identifier 'Tb' // property behavior setter thunk (not used currently) global ::= global specialization // function specialization global ::= global 'Tm' // merged function global ::= entity // some identifiable thing global ::= type type generic-signature? 'TR' // reabstraction thunk global ::= impl-function-type type generic-signature? 'Tz' index? // objc-to-swift-async completion handler block implementation global ::= impl-function-type type generic-signature? 'TZ' index? // objc-to-swift-async completion handler block implementation predefined by runtime global ::= type type type generic-signature? 'Ty' // reabstraction thunk with dynamic 'Self' capture global ::= type type generic-signature? 'Tr' // obsolete mangling for reabstraction thunk global ::= entity generic-signature? type type* 'TK' // key path getter global ::= entity generic-signature? type type* 'Tk' // key path setter global ::= entity generic-signature? type type* 'Tkmu' // key path unapplied method global ::= entity generic-signature? type type* 'TkMA' // key path applied method global ::= type generic-signature 'TH' // key path equality global ::= type generic-signature 'Th' // key path hasher global ::= global generic-signature? 'TJ' AUTODIFF-FUNCTION-KIND INDEX-SUBSET 'p' INDEX-SUBSET 'r' // autodiff function global ::= global generic-signature? 'TJV' AUTODIFF-FUNCTION-KIND INDEX-SUBSET 'p' INDEX-SUBSET 'r' // autodiff derivative vtable thunk global ::= type type 'TJO' AUTODIFF-FUNCTION-KIND // autodiff self-reordering reabstraction thunk global ::= type 'TJS' AUTODIFF-FUNCTION-KIND INDEX-SUBSET 'p' INDEX-SUBSET 'r' INDEX-SUBSET 'P' // autodiff linear map subset parameters thunk global ::= global type 'TJS' AUTODIFF-FUNCTION-KIND INDEX-SUBSET 'p' INDEX-SUBSET 'r' INDEX-SUBSET 'P' // autodiff derivative function subset parameters thunk global ::= protocol 'TL' // protocol requirements base descriptor global ::= assoc-type-name 'Tl' // associated type descriptor global ::= assoc-type-name 'TM' // default associated type witness accessor (HISTORICAL) global ::= type assoc-type-list protocol 'Tn' // associated conformance descriptor global ::= type assoc-type-list protocol 'TN' // default associated conformance witness accessor global ::= type protocol 'Tb' // base conformance descriptor REABSTRACT-THUNK-TYPE ::= 'R' // reabstraction thunk REABSTRACT-THUNK-TYPE ::= 'r' // reabstraction thunk (obsolete) global ::= global type 'TU' // reabstraction thunk with global actor constraint All reabstraction thunks have the "from" and "to" types in that order, and are always non-polymorphic ```` types. :: VALUE-WITNESS-KIND ::= 'al' // allocateBuffer VALUE-WITNESS-KIND ::= 'ca' // assignWithCopy VALUE-WITNESS-KIND ::= 'ta' // assignWithTake VALUE-WITNESS-KIND ::= 'de' // deallocateBuffer VALUE-WITNESS-KIND ::= 'xx' // destroy VALUE-WITNESS-KIND ::= 'XX' // destroyBuffer VALUE-WITNESS-KIND ::= 'Xx' // destroyArray VALUE-WITNESS-KIND ::= 'CP' // initializeBufferWithCopyOfBuffer VALUE-WITNESS-KIND ::= 'Cp' // initializeBufferWithCopy VALUE-WITNESS-KIND ::= 'cp' // initializeWithCopy VALUE-WITNESS-KIND ::= 'TK' // initializeBufferWithTakeOfBuffer VALUE-WITNESS-KIND ::= 'Tk' // initializeBufferWithTake VALUE-WITNESS-KIND ::= 'tk' // initializeWithTake VALUE-WITNESS-KIND ::= 'pr' // projectBuffer VALUE-WITNESS-KIND ::= 'xs' // storeExtraInhabitant VALUE-WITNESS-KIND ::= 'xg' // getExtraInhabitantIndex VALUE-WITNESS-KIND ::= 'Cc' // initializeArrayWithCopy VALUE-WITNESS-KIND ::= 'Tt' // initializeArrayWithTakeFrontToBack VALUE-WITNESS-KIND ::= 'tT' // initializeArrayWithTakeBackToFront VALUE-WITNESS-KIND ::= 'ug' // getEnumTag VALUE-WITNESS-KIND ::= 'up' // destructiveProjectEnumData VALUE-WITNESS-KIND ::= 'ui' // destructiveInjectEnumTag VALUE-WITNESS-KIND ::= 'et' // getEnumTagSinglePayload VALUE-WITNESS-KIND ::= 'st' // storeEnumTagSinglePayload ```` differentiates the kinds of value witness functions for a type. :: AUTODIFF-FUNCTION-KIND ::= 'f' // JVP (forward-mode derivative) AUTODIFF-FUNCTION-KIND ::= 'r' // VJP (reverse-mode derivative) AUTODIFF-FUNCTION-KIND ::= 'd' // differential AUTODIFF-FUNCTION-KIND ::= 'p' // pullback ```` differentiates the kinds of functions associated with a differentiable function used for differentiable programming. :: global ::= generic-signature? type 'WOy' // Outlined copy global ::= generic-signature? type 'WOe' // Outlined consume global ::= generic-signature? type 'WOr' // Outlined retain global ::= generic-signature? type 'WOs' // Outlined release global ::= generic-signature? type 'WOB' // Outlined initializeWithTake, not using value witness global ::= generic-signature? type 'WOb' // Outlined initializeWithTake global ::= generic-signature? type 'WOc' // Outlined initializeWithCopy global ::= generic-signature? type 'WOC' // Outlined initializeWithCopy, not using value witness global ::= generic-signature? type 'WOd' // Outlined assignWithTake global ::= generic-signature? type 'WOD' // Outlined assignWithTake, not using value witness global ::= generic-signature? type 'WOf' // Outlined assignWithCopy global ::= generic-signature? type 'WOF' // Outlined assignWithCopy, not using value witness global ::= generic-signature? type 'WOh' // Outlined destroy global ::= generic-signature? type 'WOH' // Outlined destroy, not using value witness global ::= generic-signature? type 'WOi' // Outlined store enum tag global ::= generic-signature? type 'WOj' // Outlined enum destructive project global ::= generic-signature? type 'WOg' // Outlined enum get tag Entities ~~~~~~~~ :: entity ::= nominal-type // named type declaration entity ::= context entity-spec static? curry-thunk? static ::= 'Z' curry-thunk ::= 'Tc' label-list ::= empty-list // represents complete absence of parameter labels label-list ::= label* // '_' is inserted as placeholder for empty label, // since the number of labels should match the number of parameters label ::= '_' // empty label label ::= identifier // label // The leading type is the function type entity-spec ::= label-list type file-discriminator? 'fC' // allocating constructor entity-spec ::= label-list type file-discriminator? 'fc' // non-allocating constructor entity-spec ::= type 'fU' INDEX // explicit anonymous closure expression entity-spec ::= type 'fu' INDEX // implicit anonymous closure entity-spec ::= 'fA' INDEX // default argument N+1 generator entity-spec ::= entity 'fa' // runtime discoverable attribute generator entity-spec ::= 'fi' // non-local variable initializer entity-spec ::= 'fP' // property wrapper backing initializer entity-spec ::= 'fW' // property wrapper init from projected value entity-spec ::= 'fD' // deallocating destructor; untyped entity-spec ::= 'fZ' // isolated deallocating destructor; untyped entity-spec ::= 'fd' // non-deallocating destructor; untyped entity-spec ::= 'fE' // ivar destroyer; untyped entity-spec ::= 'fe' // ivar initializer; untyped entity-spec ::= 'Tv' NATURAL // outlined global variable (from context function) entity-spec ::= 'Tv' NATURAL 'r' // outlined global read-only object entity-spec ::= 'Te' bridge-spec // outlined objective c method call entity-spec ::= decl-name label-list function-signature generic-signature? 'F' // function entity-spec ::= label-list type file-discriminator? 'i' ACCESSOR // subscript entity-spec ::= decl-name label-list? type 'v' ACCESSOR // variable entity-spec ::= decl-name type 'fp' // generic type parameter entity-spec ::= decl-name type 'fo' // enum element (currently not used) entity-spec ::= decl-name label-list? type generic-signature? 'fm' // macro entity-spec ::= context macro-discriminator-list // macro expansion entity-spec ::= identifier 'Qa' // associated type declaration ACCESSOR ::= 'm' // materializeForSet ACCESSOR ::= 's' // setter ACCESSOR ::= 'g' // getter ACCESSOR ::= 'G' // global getter ACCESSOR ::= 'w' // willSet ACCESSOR ::= 'W' // didSet ACCESSOR ::= 'r' // _read ACCESSOR ::= 'M' // _modify (temporary) ACCESSOR ::= 'a' ADDRESSOR-KIND // mutable addressor ACCESSOR ::= 'l' ADDRESSOR-KIND // non-mutable addressor ACCESSOR ::= 'p' // pseudo accessor referring to the storage itself ACCESSOR ::= 'x' // modify ACCESSOR ::= 'y' // read ADDRESSOR-KIND ::= 'u' // unsafe addressor (no owner) ADDRESSOR-KIND ::= 'O' // owning addressor (non-native owner), not used anymore ADDRESSOR-KIND ::= 'o' // owning addressor (native owner), not used anymore ADDRESSOR-KIND ::= 'p' // pinning addressor (native owner), not used anymore decl-name ::= identifier decl-name ::= identifier 'L' INDEX // locally-discriminated declaration decl-name ::= identifier identifier 'LL' // file-discriminated declaration decl-name ::= identifier 'L' RELATED-DISCRIMINATOR // related declaration RELATED-DISCRIMINATOR ::= [a-j] RELATED-DISCRIMINATOR ::= [A-J] macro-discriminator-list ::= macro-discriminator-list? file-discriminator? macro-expansion-operator INDEX macro-expansion-operator ::= decl-name identifier 'fMa' // attached accessor macro macro-expansion-operator ::= decl-name identifier 'fMr' // attached member-attribute macro macro-expansion-operator ::= identifier 'fMf' // freestanding macro macro-expansion-operator ::= decl-name identifier 'fMm' // attached member macro macro-expansion-operator ::= decl-name identifier 'fMp' // attached peer macro macro-expansion-operator ::= decl-name identifier 'fMc' // attached conformance macro macro-expansion-operator ::= decl-name identifier 'fMe' // attached extension macro macro-expansion-operator ::= decl-name identifier 'fMq' // attached preamble macro macro-expansion-operator ::= decl-name identifier 'fMb' // attached body macro macro-expansion-operator ::= decl-name identifier 'fMu' // uniquely-named entity file-discriminator ::= identifier 'Ll' // anonymous file-discriminated declaration The identifier in a ```` and the second identifier in a file-discriminated ```` is a string that represents the file the original declaration came from. It should be considered unique within the enclosing module. The first identifier is the name of the entity. Not all declarations marked ``private`` declarations will use this mangling; if the entity's context is enough to uniquely identify the entity, the simple ``identifier`` form is preferred. Twenty operators of the form 'LA', 'LB', etc. are reserved to described entities related to the entity whose name is provided. For example, 'LE' and 'Le' in the "SC" module are used to represent the structs synthesized by the Clang importer for various "error code" enums. Outlined bridged Objective C method call mangling includes which parameters and return value are bridged and the type of pattern outlined. :: bridge-spec ::= bridged-kind bridged-param* bridged-return '_' bridged-param ::= 'n' // not bridged parameter bridged-param ::= 'b' // bridged parameter bridged-return ::= 'n' // not bridged return bridged-return ::= 'b' // bridged return bridged-kind ::= 'm' // bridged method bridged-kind ::= 'a' // bridged property (by address) bridged-kind ::= 'p' // bridged property (by value) Declaration Contexts ~~~~~~~~~~~~~~~~~~~~ These manglings identify the enclosing context in which an entity was declared, such as its enclosing module, function, or nominal type. :: context ::= module context ::= entity context ::= entity module generic-signature? 'E' An ``extension`` mangling is used whenever an entity's declaration context is an extension *and* the entity being extended is in a different module. In this case the extension's module is mangled first, followed by the entity being extended. If the extension and the extended entity are in the same module, the plain ``entity`` mangling is preferred, but not always used. An extension is considered "constrained" if it: - Has any requirements not already satisfied by the extended nominal, excluding conformance requirements for invertible protocols. - Has any generic parameters with an inverse requirement. Those requirements included in any of the above are included in the extension's generic signature. The reason for this additional complexity is that we do not mangle conformance req's for invertible protocols, only their absence. :: struct S {} // An unconstrained extension. extension S {} // Also an unconstrained extension, because there are no inverses to mangle. // This extension is exactly the same as the previous. extension S where A: Copyable, B: Copyable {} // A constrained extension, because of the added requirement `B: P` that is // not already present in S. extension S where B: P {} // A constrained extension, because of the absence of `A: Copyable`. // Despite also being absent in `S`, absences of invertible protocols // are always mangled. extension S where A: ~Copyable {} Some entities, like computed properties, rely on the generic signature in their `context`, so in order to disambiguate between those properties and those in a context where a generic type requires Copyable, which is not mangled, we have the following rule: If the innermost type declaration for an entity has any inverses in its generic signature, then extension mangling is used. This strategy is used to ensure that moving a declaration between a nominal type and one of its extensions does not cause an ABI break if the generic signature of the entity is equivalent in both circumstances. For example: :: struct R { func f1() {} // uses extension mangling, just like `f3` func f2() where A: Copyable {} } extension R where A: ~Copyable { func f3() {} func f4() where A: Copyable {} // uses entity mangling, just like `f2` } extension R where A: Copyable { // 'f5' is mangled equivalent to 'f2' and 'f4' modulo its identifier. func f5() {} } For intermediate nested types, i.e., those between the top level and the entity, any inverses that remain in at the signature of the entity are mangled into that entity's generic signature: :: struct X { struct Y { // 'g1' uses 'entity' context mangling with and has no mangled signatures. func g1() where A: Copyable, B: Copyable {} // 'g2' uses 'entity' context mangling. The requirement `B: ~Copyable` is //mangled into the generic signature for 'g2'. func g2() where A: Copyable {} // 'g3' uses extension mangling with generic signature 'A: ~Copyable'. // The mangled generic signature of 'g3' is empty. func g3() where B: Copyable {} // 'g4' uses extension mangling with generic signature 'A: ~Copyable'. // The mangled generic signature of 'g4' contains 'B: ~Copyable'. func g4() {} } } When mangling the context of a local entity within a constructor or destructor, the non-allocating or non-deallocating variant is used. :: module ::= identifier // module name module ::= known-module // abbreviation context ::= entity identifier type-list 'XZ' // unknown runtime context The runtime produces manglings of unknown runtime contexts when a declaration context has no preserved runtime information, or when a declaration is encoded in runtime in a way that the current runtime does not understand. These manglings are unstable and may change between runs of the process. :: known-module ::= 's' // Swift known-module ::= 'SC' // Clang-importer-synthesized known-module ::= 'So' // C and Objective-C The Objective-C module is used as the context for mangling Objective-C classes as ````\ s. Types ~~~~~ :: any-generic-type ::= substitution any-generic-type ::= context decl-name 'C' // nominal class type any-generic-type ::= context decl-name 'O' // nominal enum type any-generic-type ::= context decl-name 'V' // nominal struct type any-generic-type ::= context decl-name 'XY' // unknown nominal type any-generic-type ::= protocol 'P' // nominal protocol type any-generic-type ::= standard-substitutions nominal-type ::= any-generic-type // nominal type standard-substitutions ::= 'S' KNOWN-TYPE-KIND // known nominal type substitution standard-substitutions ::= 'S' NATURAL KNOWN-TYPE-KIND // repeated known type substitutions of the same kind KNOWN-TYPE-KIND ::= 'A' // Swift.AutoreleasingUnsafeMutablePointer KNOWN-TYPE-KIND ::= 'a' // Swift.Array KNOWN-TYPE-KIND ::= 'B' // Swift.BinaryFloatingPoint KNOWN-TYPE-KIND ::= 'b' // Swift.Bool KNOWN-TYPE-KIND ::= 'c' KNOWN-TYPE-KIND-2 // Second set of standard types KNOWN-TYPE-KIND ::= 'D' // Swift.Dictionary KNOWN-TYPE-KIND ::= 'd' // Swift.Float64 KNOWN-TYPE-KIND ::= 'E' // Swift.Encodable KNOWN-TYPE-KIND ::= 'e' // Swift.Decodable KNOWN-TYPE-KIND ::= 'F' // Swift.FloatingPoint KNOWN-TYPE-KIND ::= 'f' // Swift.Float32 KNOWN-TYPE-KIND ::= 'G' // Swift.RandomNumberGenerator KNOWN-TYPE-KIND ::= 'H' // Swift.Hashable KNOWN-TYPE-KIND ::= 'h' // Swift.Set KNOWN-TYPE-KIND ::= 'I' // Swift.DefaultIndices KNOWN-TYPE-KIND ::= 'i' // Swift.Int KNOWN-TYPE-KIND ::= 'J' // Swift.Character KNOWN-TYPE-KIND ::= 'j' // Swift.Numeric KNOWN-TYPE-KIND ::= 'K' // Swift.BidirectionalCollection KNOWN-TYPE-KIND ::= 'k' // Swift.RandomAccessCollection KNOWN-TYPE-KIND ::= 'L' // Swift.Comparable KNOWN-TYPE-KIND ::= 'l' // Swift.Collection KNOWN-TYPE-KIND ::= 'M' // Swift.MutableCollection KNOWN-TYPE-KIND ::= 'm' // Swift.RangeReplaceableCollection KNOWN-TYPE-KIND ::= 'N' // Swift.ClosedRange KNOWN-TYPE-KIND ::= 'n' // Swift.Range KNOWN-TYPE-KIND ::= 'O' // Swift.ObjectIdentifier KNOWN-TYPE-KIND ::= 'P' // Swift.UnsafePointer KNOWN-TYPE-KIND ::= 'p' // Swift.UnsafeMutablePointer KNOWN-TYPE-KIND ::= 'Q' // Swift.Equatable KNOWN-TYPE-KIND ::= 'q' // Swift.Optional KNOWN-TYPE-KIND ::= 'R' // Swift.UnsafeBufferPointer KNOWN-TYPE-KIND ::= 'r' // Swift.UnsafeMutableBufferPointer KNOWN-TYPE-KIND ::= 'S' // Swift.String KNOWN-TYPE-KIND ::= 's' // Swift.Substring KNOWN-TYPE-KIND ::= 'T' // Swift.Sequence KNOWN-TYPE-KIND ::= 't' // Swift.IteratorProtocol KNOWN-TYPE-KIND ::= 'U' // Swift.UnsignedInteger KNOWN-TYPE-KIND ::= 'u' // Swift.UInt KNOWN-TYPE-KIND ::= 'V' // Swift.UnsafeRawPointer KNOWN-TYPE-KIND ::= 'v' // Swift.UnsafeMutableRawPointer KNOWN-TYPE-KIND ::= 'W' // Swift.UnsafeRawBufferPointer KNOWN-TYPE-KIND ::= 'w' // Swift.UnsafeMutableRawBufferPointer KNOWN-TYPE-KIND ::= 'X' // Swift.RangeExpression KNOWN-TYPE-KIND ::= 'x' // Swift.Strideable KNOWN-TYPE-KIND ::= 'Y' // Swift.RawRepresentable KNOWN-TYPE-KIND ::= 'y' // Swift.StringProtocol KNOWN-TYPE-KIND ::= 'Z' // Swift.SignedInteger KNOWN-TYPE-KIND ::= 'z' // Swift.BinaryInteger KNOWN-TYPE-KIND-2 ::= 'A' // Swift.Actor KNOWN-TYPE-KIND-2 ::= 'C' // Swift.CheckedContinuation KNOWN-TYPE-KIND-2 ::= 'c' // Swift.UnsafeContinuation KNOWN-TYPE-KIND-2 ::= 'E' // Swift.CancellationError KNOWN-TYPE-KIND-2 ::= 'e' // Swift.UnownedSerialExecutor KNOWN-TYPE-KIND-2 ::= 'F' // Swift.Executor KNOWN-TYPE-KIND-2 ::= 'f' // Swift.SerialExecutor KNOWN-TYPE-KIND-2 ::= 'G' // Swift.TaskGroup KNOWN-TYPE-KIND-2 ::= 'g' // Swift.ThrowingTaskGroup KNOWN-TYPE-KIND-2 ::= 'I' // Swift.AsyncIteratorProtocol KNOWN-TYPE-KIND-2 ::= 'i' // Swift.AsyncSequence KNOWN-TYPE-KIND-2 ::= 'J' // Swift.UnownedJob KNOWN-TYPE-KIND-2 ::= 'M' // Swift.MainActor KNOWN-TYPE-KIND-2 ::= 'P' // Swift.TaskPriority KNOWN-TYPE-KIND-2 ::= 'S' // Swift.AsyncStream KNOWN-TYPE-KIND-2 ::= 's' // Swift.AsyncThrowingStream KNOWN-TYPE-KIND-2 ::= 'T' // Swift.Task KNOWN-TYPE-KIND-2 ::= 't' // Swift.UnsafeCurrentTask protocol ::= context decl-name protocol ::= standard-substitutions type ::= 'Bb' // Builtin.BridgeObject type ::= 'BB' // Builtin.UnsafeValueBuffer #if SWIFT_RUNTIME_VERSION >= 5.5 type ::= 'Bc' // Builtin.RawUnsafeContinuation type ::= 'BD' // Builtin.DefaultActorStorage type ::= 'Be' // Builtin.Executor #endif #if SWIFT_RUNTIME_VERSION >= 5.9 type ::= 'Bd' // Builtin.NonDefaultDistributedActorStorage #endif type ::= 'Bf' NATURAL '_' // Builtin.Float type ::= 'Bi' NATURAL '_' // Builtin.Int type ::= 'BI' // Builtin.IntLiteral #if SWIFT_RUNTIME_VERSION >= 5.5 type ::= 'Bj' // Builtin.Job #endif type ::= 'BP' // Builtin.PackIndex type ::= 'BO' // Builtin.UnknownObject (no longer a distinct type, but still used for AnyObject) type ::= 'Bo' // Builtin.NativeObject type ::= 'Bp' // Builtin.RawPointer type ::= 'Bt' // Builtin.SILToken type ::= type 'Bv' NATURAL '_' // Builtin.Vecx type ::= type type 'BV' // Builtin.FixedArray type ::= 'Bw' // Builtin.Word type ::= function-signature 'c' // function type (escaping) type ::= function-signature 'X' FUNCTION-KIND // special function type type ::= bound-generic-type type ::= type 'Sg' // optional type, shortcut for: type 'ySqG' type ::= type 'Xo' // @unowned type type ::= type 'Xu' // @unowned(unsafe) type type ::= type 'Xw' // @weak type type ::= impl-function-type 'XF' // function implementation type (currently unused) type ::= type 'Xb' // SIL @box type (deprecated) type ::= type-list 'Xx' // SIL box type type ::= type-list type-list generic-signature 'XX' // Generic SIL box type type ::= type 'XD' // dynamic self type type ::= type 'm' // metatype without representation type ::= type 'XM' METATYPE-REPR // metatype with representation type ::= type 'Xp' // existential metatype without representation type ::= type 'Xm' METATYPE-REPR // existential metatype with representation type ::= 'Xe' // error or unresolved type #if SWIFT_RUNTIME_VERSION >= 6.TBD type ::= '$' 'n'? INDEX // integer type #endif bound-generic-type ::= type bound-generic-args 'G' // one type-list per nesting level of type bound-generic-type ::= substitution bound-generic-args ::= 'y' (type* '_')* type* retroactive-conformance* // generic arguments FUNCTION-KIND ::= 'f' // @thin function type FUNCTION-KIND ::= 'U' // uncurried function type (currently not used) FUNCTION-KIND ::= 'K' // @auto_closure function type (noescape) FUNCTION-KIND ::= 'B' // objc block function type FUNCTION-KIND ::= 'zB' C-TYPE // objc block type with non-canonical C type FUNCTION-KIND ::= 'L' // objc block function type with canonical C type (escaping) (DWARF only; otherwise use 'B' or 'zB' C-TYPE) FUNCTION-KIND ::= 'C' // C function pointer / C++ method type FUNCTION-KIND ::= 'zC' C-TYPE // C function pointer / C++ method type with non-canonical C type FUNCTION-KIND ::= 'A' // @auto_closure function type (escaping) FUNCTION-KIND ::= 'E' // function type (noescape) C-TYPE ::= NATURAL IDENTIFIER-STRING // raw Itanium mangling function-signature ::= result-type params-type async? sendable? throws? differentiable? function-isolation? sending-result? // results and parameters result-type ::= type result-type ::= empty-list // shortcut for () params-type ::= type 'z'? 'h'? // tuple in case of multiple parameters or a single parameter with a single tuple type // with optional inout convention, shared convention. parameters don't have labels, // they are mangled separately as part of the entity. params-type ::= empty-list // shortcut for no parameters #if SWIFT_RUNTIME_VERSION >= 5.5 async ::= 'Ya' // 'async' annotation on function types sendable ::= 'Yb' // @Sendable on function types function-isolation ::= type 'Yc' // Global actor on function type #endif throws ::= 'K' // 'throws' annotation on function types #if SWIFT_RUNTIME_VERSION >= 6.0 throws ::= type 'YK' // 'throws(type)' annotation on function types function-isolation ::= type 'YA' // @isolated(any) on function type sending-result ::= 'YT' // -> sending T #endif #if SWIFT_RUNTIME_VERSION >= 6.2 function-isolation :== 'YC' // nonisolated(nonsending) on function type #endif differentiable ::= 'Yjf' // @differentiable(_forward) on function type differentiable ::= 'Yjr' // @differentiable(reverse) on function type differentiable ::= 'Yjd' // @differentiable on function type differentiable ::= 'Yjl' // @differentiable(_linear) on function type type-list ::= list-type '_' list-type* // list of types type-list ::= empty-list // FIXME: Consider replacing 'h' with a two-char code list-type ::= type identifier? 'Yk'? 'z'? 'h'? 'n'? 'Yi'? 'd'? 'Yt'? // type with optional label, '@noDerivative', inout convention, shared convention, owned convention, actor 'isolated', variadic specifier, and compile-time constant In the mangling of C function types,``C-TYPE`` is mangled according to the Itanium ABI, prefixed with its length. This resembles the mangling of ``identifier``, but it does not honor substitutions or Punycode. The 6.0 Swift runtime supports demangling ``sending-result``, but has a bug when it's combined with ``function-isolation``. :: METATYPE-REPR ::= 't' // Thin metatype representation METATYPE-REPR ::= 'T' // Thick metatype representation METATYPE-REPR ::= 'o' // ObjC metatype representation existential-layout ::= protocol-list 'p' // existential layout existential-layout ::= protocol-list type 'Xc' // existential layout with superclass existential-layout ::= protocol-list 'Xl' // existential layout with AnyObject type ::= associated-type type ::= any-generic-type type ::= existential-layout // existential type type ::= existential-layout requirement '_' requirement* 'XP' // constrained existential type type ::= type-list 't' // tuple type ::= type generic-signature 'u' // generic type type ::= 'x' // generic param, depth=0, idx=0 type ::= 'q' GENERIC-PARAM-INDEX // dependent generic parameter type ::= type assoc-type-name 'qa' // associated type of non-generic param type ::= assoc-type-name 'Qy' GENERIC-PARAM-INDEX // associated type type ::= assoc-type-name 'Qz' // shortcut for 'Qyz' type ::= assoc-type-list 'QY' GENERIC-PARAM-INDEX // associated type at depth type ::= assoc-type-list 'QZ' // shortcut for 'QYz' type ::= type 'Qe' INDEX // pack element type type ::= type type 'Qp' // pack expansion type (pattern, count) type ::= pack-element-list 'QP' // pack type type ::= pack-element-list 'QS' DIRECTNESS // SIL pack type pack-element-list ::= type '_' type* pack-element-list ::= empty-list #if SWIFT_RUNTIME_VERSION >= 5.2 type ::= type assoc-type-name 'Qx' // associated type relative to base `type` type ::= type assoc-type-list 'QX' // associated type relative to base `type` list #endif #if SWIFT_RUNTIME_VERSION >= 5.7 type ::= symbolic-extended-existential-type-shape type* retroactive-conformance* 'Xj' #endif protocol-list ::= protocol '_' protocol* protocol-list ::= empty-list assoc-type-list ::= assoc-type-name '_' assoc-type-name* associated-type ::= substitution associated-type ::= type identifier 'Qa' // associated type assoc-type-name ::= identifier // associated type name without protocol assoc-type-name ::= identifier protocol 'P' // associated type name with protocol empty-list ::= 'y' Associated types use an abbreviated mangling when the base generic parameter or associated type is constrained by a single protocol requirement. The associated type in this case can be referenced unambiguously by name alone. If the base has multiple conformance constraints, then the protocol name is mangled in to disambiguate. :: impl-function-type ::= type* 'I' FUNC-ATTRIBUTES '_' impl-function-type ::= type* generic-signature 'I' FUNC-ATTRIBUTES '_' FUNC-ATTRIBUTES ::= PATTERN-SUBS? INVOCATION-SUB? PSEUDO-GENERIC? CALLEE-ESCAPE? ISOLATION? DIFFERENTIABILITY-KIND? CALLEE-CONVENTION FUNC-REPRESENTATION? COROUTINE-KIND? SENDABLE? ASYNC? SENDING-RESULT? (PARAM-CONVENTION PARAM-DIFFERENTIABILITY?)* RESULT-CONVENTION* ('Y' PARAM-CONVENTION)* ('z' RESULT-CONVENTION RESULT-DIFFERENTIABILITY?)? PATTERN-SUBS ::= 's' // has pattern substitutions INVOCATION-SUB ::= 'I' // has invocation substitutions PSEUDO-GENERIC ::= 'P' CALLEE-ESCAPE ::= 'e' // @escaping (inverse of SIL @noescape) ISOLATION ::= 'A' // @isolated(any) DIFFERENTIABILITY-KIND ::= 'd' // @differentiable DIFFERENTIABILITY-KIND ::= 'l' // @differentiable(_linear) DIFFERENTIABILITY-KIND ::= 'f' // @differentiable(_forward) DIFFERENTIABILITY-KIND ::= 'r' // @differentiable(reverse) CALLEE-CONVENTION ::= 'y' // @callee_unowned CALLEE-CONVENTION ::= 'g' // @callee_guaranteed CALLEE-CONVENTION ::= 'x' // @callee_owned CALLEE-CONVENTION ::= 't' // thin FUNC-REPRESENTATION ::= 'B' // C block invocation function FUNC-REPRESENTATION ::= 'zB' C-TYPE // C block invocation function with non-canonical C type FUNC-REPRESENTATION ::= 'C' // C global function FUNC-REPRESENTATION ::= 'zC' C-TYPE // C global function with non-canonical C type FUNC-REPRESENTATION ::= 'M' // Swift method FUNC-REPRESENTATION ::= 'J' // ObjC method FUNC-REPRESENTATION ::= 'K' // closure FUNC-REPRESENTATION ::= 'W' // protocol witness COROUTINE-KIND ::= 'A' // yield-once coroutine COROUTINE-KIND ::= 'I' // yield-once-2 coroutine COROUTINE-KIND ::= 'G' // yield-many coroutine #if SWIFT_RUNTIME_VERSION >= 5.5 SENDABLE ::= 'h' // @Sendable ASYNC ::= 'H' // @async #endif #if SWIFT_RUNTIME_VERSION >= 6.0 SENDING-RESULT ::= 'T' // sending result #endif PARAM-CONVENTION ::= 'i' // indirect in PARAM-CONVENTION ::= 'c' // indirect in constant PARAM-CONVENTION ::= 'l' // indirect inout PARAM-CONVENTION ::= 'b' // indirect inout aliasable PARAM-CONVENTION ::= 'n' // indirect in guaranteed PARAM-CONVENTION ::= 'X' // indirect in C++ PARAM-CONVENTION ::= 'x' // direct owned PARAM-CONVENTION ::= 'y' // direct unowned PARAM-CONVENTION ::= 'g' // direct guaranteed PARAM-CONVENTION ::= 'e' // direct deallocating PARAM-CONVENTION ::= 'v' // pack owned PARAM-CONVENTION ::= 'p' // pack guaranteed PARAM-CONVENTION ::= 'm' // pack inout PARAM-DIFFERENTIABILITY ::= 'w' // @noDerivative RESULT-CONVENTION ::= 'r' // indirect RESULT-CONVENTION ::= 'o' // owned RESULT-CONVENTION ::= 'd' // unowned RESULT-CONVENTION ::= 'u' // unowned inner pointer RESULT-CONVENTION ::= 'a' // auto-released RESULT-CONVENTION ::= 'k' // pack RESULT-DIFFERENTIABILITY ::= 'w' // @noDerivative DIRECTNESS ::= 'i' // indirect DIRECTNESS ::= 'd' // direct For the most part, manglings follow the structure of formal language types. However, in some cases it is more useful to encode the exact implementation details of a function type. :: #if SWIFT_VERSION >= 5.1 type ::= 'Qr' // opaque result type (of current decl, used for the first opaque type parameter only) type ::= 'QR' INDEX // same as above, for subsequent opaque type parameters, INDEX is the ordinal -1 type ::= opaque-type-decl-name bound-generic-args 'Qo' INDEX // opaque type opaque-type-decl-name ::= entity 'QO' // opaque result type of specified decl #endif #if SWIFT_VERSION >= 5.4 type ::= 'Qu' // opaque result type (of current decl, first param) // used for ObjC class runtime name purposes. type ::= 'QU' INDEX #endif Opaque return types have a special short representation in the mangling of their defining entity. In structural position, opaque types are fully qualified by mangling the defining entity for the opaque declaration and the substitutions into the defining entity's generic environment. The ``type*`` list contains parameter and return types (including the error result), in that order. The number of parameters and results must match with the number of ```` and ```` characters after the ````. The ```` is used if the function is polymorphic. DWARF debug info and USRs also mangle sugared types, adding the following productions: :: any-generic-type ::= context decl-name 'a' // typealias type type ::= type 'XSq' // sugared Optional type type ::= type 'XSa' // sugared Array type type ::= type type 'XSD' // sugared Dictionary type (key, value) type ::= type type 'XSA' // sugared InlineArray type (count, element) Generics ~~~~~~~~ :: protocol-conformance-context ::= protocol module generic-signature? protocol-conformance ::= type protocol-conformance-context ```` refers to a type's conformance to a protocol. The named module is the one containing the extension or type declaration that declared the conformance. :: protocol-conformance ::= type protocol If ``type`` is a generic parameter or associated type of one, then no module is mangled, because the conformance must be resolved from the generic environment. protocol-conformance ::= context identifier protocol identifier generic-signature? // Property behavior conformance Property behaviors are implemented using private protocol conformances. :: concrete-protocol-conformance ::= type protocol-conformance-ref any-protocol-conformance-list 'HC' protocol-conformance-ref ::= protocol 'HP' // same module as conforming type protocol-conformance-ref ::= protocol 'Hp' // same module as protocol protocol-conformance-ref ::= protocol module // "retroactive" any-protocol-conformance ::= concrete-protocol-conformance any-protocol-conformance ::= dependent-protocol-conformance any-protocol-conformance ::= pack-protocol-conformance any-protocol-conformance-list ::= any-protocol-conformance '_' any-protocol-conformance-list any-protocol-conformance-list ::= empty-list DEPENDENT-CONFORMANCE-INDEX ::= INDEX dependent-protocol-conformance ::= type protocol 'HD' DEPENDENT-CONFORMANCE-INDEX dependent-protocol-conformance ::= dependent-protocol-conformance protocol 'HI' DEPENDENT-CONFORMANCE-INDEX dependent-protocol-conformance ::= dependent-protocol-conformance dependent-associated-conformance 'HA' DEPENDENT-CONFORMANCE-INDEX dependent-associated-conformance ::= type protocol dependent-protocol-conformance ::= dependent-protocol-conformance type 'HO' pack-protocol-conformance ::= any-protocol-conformance-list 'HX' A compact representation used to represent mangled protocol conformance witness arguments at runtime. The ``module`` is only specified for conformances that are "retroactive", meaning that the context in which the conformance is defined is in neither the protocol or type module. For a non-retroactive conformance where both the type *and* the protocol are in the same module, or for synthesized conformances that have no owning module, the "HP" operator is preferred. The concrete protocol conformances that follow are for the conditional conformance requirements. Dependent protocol conformances mangle the access path required to extract a protocol conformance from some conformance passed into the environment. The first case (operator "HD") is the leaf requirement, containing a dependent type and the protocol it conforms to. The remaining dependent protocol conformance manglings describe lookups performed on their child dependent protocol conformances. The "HI" operator retrieves the named inherited protocol from the witness table produced by the child. The "HA" operator refers to an associated conformance within the witness table, identified by the dependent type and protocol. In all cases, the DEPENDENT-CONFORMANCE-INDEX is an INDEX value indicating the position of the appropriate value within the generic environment (for "HD") or witness table (for "HI" and "HA") when it is known to be at a fixed position. An index of 1 ("0\_") is used to indicate "unknown"; all other values are adjusted by 2. That these indexes are not 0-based is a bug that's now codified into the ABI; the index 0 is therefore reserved. :: generic-signature ::= requirement* generic-param-marker 'l' // one generic parameter generic-signature ::= requirement* generic-param-marker* 'r' GENERIC-PARAM-COUNT* 'l' generic-param-marker ::= generic-param-pack-marker generic-param-marker ::= generic-param-value-marker generic-param-pack-marker ::= 'Rv' GENERIC-PARAM-INDEX // generic parameter pack marker #if SWIFT_RUNTIME_VERSION >= 6.TBD generic-param-value-marker ::= type 'RV' GENERIC-PARAM-INDEX // generic parameter value marker #endif GENERIC-PARAM-COUNT ::= 'z' // zero parameters GENERIC-PARAM-COUNT ::= INDEX // N+1 parameters requirement ::= protocol 'R' GENERIC-PARAM-INDEX // protocol requirement requirement ::= protocol assoc-type-name 'Rp' GENERIC-PARAM-INDEX // protocol requirement on associated type requirement ::= protocol assoc-type-list 'RP' GENERIC-PARAM-INDEX // protocol requirement on associated type at depth requirement ::= protocol substitution 'RQ' // protocol requirement with substitution #if SWIFT_RUNTIME_VERSION >= 6.0 requirement ::= 'Ri' INDEX GENERIC-PARAM-INDEX // inverse requirement on generic parameter where INDEX is the bit number requirement ::= substitution 'RI' INDEX // inverse requirement with substitution requirement ::= assoc-type-name 'Rj' INDEX GENERIC-PARAM-INDEX // inverse requirement on associated type requirement ::= assoc-type-list 'RJ' INDEX GENERIC-PARAM-INDEX // inverse requirement on associated type at depth #endif requirement ::= type 'Rb' GENERIC-PARAM-INDEX // base class requirement requirement ::= type assoc-type-name 'Rc' GENERIC-PARAM-INDEX // base class requirement on associated type requirement ::= type assoc-type-list 'RC' GENERIC-PARAM-INDEX // base class requirement on associated type at depth requirement ::= type substitution 'RB' // base class requirement with substitution requirement ::= type 'Rs' GENERIC-PARAM-INDEX // same-type requirement requirement ::= type assoc-type-name 'Rt' GENERIC-PARAM-INDEX // same-type requirement on associated type requirement ::= type assoc-type-list 'RT' GENERIC-PARAM-INDEX // same-type requirement on associated type at depth requirement ::= type substitution 'RS' // same-type requirement with substitution requirement ::= type 'Rl' GENERIC-PARAM-INDEX LAYOUT-CONSTRAINT // layout requirement requirement ::= type assoc-type-name 'Rm' GENERIC-PARAM-INDEX LAYOUT-CONSTRAINT // layout requirement on associated type requirement ::= type assoc-type-list 'RM' GENERIC-PARAM-INDEX LAYOUT-CONSTRAINT // layout requirement on associated type at depth requirement ::= type substitution 'RM' LAYOUT-CONSTRAINT // layout requirement with substitution requirement ::= type 'Rh' GENERIC-PARAM-INDEX // same-shape requirement (only supported on a generic parameter) GENERIC-PARAM-INDEX ::= 'z' // depth = 0, idx = 0 GENERIC-PARAM-INDEX ::= INDEX // depth = 0, idx = N+1 GENERIC-PARAM-INDEX ::= 'd' INDEX INDEX // depth = M+1, idx = N GENERIC-PARAM-INDEX ::= 's' // depth = 0, idx = 0; Constrained existential 'Self' type LAYOUT-CONSTRAINT ::= 'N' // NativeRefCountedObject LAYOUT-CONSTRAINT ::= 'R' // RefCountedObject LAYOUT-CONSTRAINT ::= 'T' // Trivial LAYOUT-CONSTRAINT ::= 'C' // Class LAYOUT-CONSTRAINT ::= 'D' // NativeClass LAYOUT-CONSTRAINT ::= 'E' LAYOUT-SIZE-AND-ALIGNMENT // Trivial of exact size and alignment LAYOUT-CONSTRAINT ::= 'e' LAYOUT-SIZE // Trivial of exact size LAYOUT-CONSTRAINT ::= 'M' LAYOUT-SIZE-AND-ALIGNMENT // Trivial of size and alignment at most N bits LAYOUT-CONSTRAINT ::= 'm' LAYOUT-SIZE // Trivial of size at most N bits LAYOUT-CONSTRAINT ::= 'U' // Unknown layout LAYOUT-CONSTRAINT ::= 'B' // BridgeObject LAYOUT-CONSTRAINT ::= 'S' // TrivialStride LAYOUT-SIZE ::= INDEX // Size only LAYOUT-SIZE-AND-ALIGNMENT ::= INDEX INDEX // Size followed by alignment A generic signature begins with an optional list of requirements. This is followed by an optional list of generic-param-pack-markers to record which generic parameters are packs (variadic). The ```` describes the number of generic parameters at each depth of the signature. As a special case, no ```` values indicates a single generic parameter at the outermost depth:: x_xCru // T_0_0 -> T_0_0 d_0__xCr_0_u // T_0_0 -> T_1_1 A generic signature must only precede an operator character which is different from any character in a ````. :: retroactive-conformance ::= any-protocol-conformance 'g' INDEX When a protocol conformance used to satisfy one of a bound generic type's generic requirements is retroactive (i.e., it is specified in a module other than the module of the conforming type or the conformed-to protocol), it is mangled with its offset into the set of conformance requirements, the root protocol conformance, and the suffix 'g'. :: // No generalization signature. extended-existential-shape ::= type 'Xg' // no generalization signature extended-existential-shape ::= generic-signature type 'XG' Identifiers ~~~~~~~~~~~ :: identifier ::= substitution identifier ::= NATURAL IDENTIFIER-STRING // identifier without word substitutions identifier ::= '0' IDENTIFIER-PART // identifier with word substitutions IDENTIFIER-PART ::= NATURAL IDENTIFIER-STRING IDENTIFIER-PART ::= [a-z] // word substitution (except the last one) IDENTIFIER-PART ::= [A-Z] // last word substitution in identifier IDENTIFIER-STRING ::= IDENTIFIER-START-CHAR IDENTIFIER-CHAR* IDENTIFIER-START-CHAR ::= [_a-zA-Z] IDENTIFIER-CHAR ::= [_$a-zA-Z0-9] ```` is run-length encoded: the natural indicates how many characters follow. Operator characters are mapped to letter characters as given. In neither case can an identifier start with a digit, so there's no ambiguity with the run-length. If the run-length start with a ``0`` the identifier string contains word substitutions. A word is a sub-string of an identifier which contains letters and digits ``[A-Za-z0-9]``. Words are separated by underscores ``_``. In addition a new word begins with an uppercase letter ``[A-Z]`` if the previous character is not an uppercase letter:: Abc1DefG2HI // contains four words 'Abc1', 'Def' and 'G2' and 'HI' _abc1_def_G2hi // contains three words 'abc1', 'def' and G2hi The words of all identifiers, which are encoded in the current mangling are enumerated and assigned to a letter: a = first word, b = second word, etc. An identifier containing word substitutions is a sequence of run-length encoded sub-strings and references to previously mangled words. All but the last word-references are lowercase letters and the last one is an uppercase letter. If there is no literal sub-string after the last word-reference, the last word-reference is followed by a ``0``. Let's assume the current mangling already encoded the identifier ``AbcDefGHI``:: 02Myac1_B // expands to: MyAbcGHI_Def A maximum of 26 words in a mangling can be used for substitutions. :: identifier ::= '00' natural '_'? IDENTIFIER-CHAR+ // '_' is inserted if the identifier starts with a digit or '_'. Identifiers that contain non-ASCII characters are encoded using the Punycode algorithm specified in RFC 3492, with the modifications that ``_`` is used as the encoding delimiter, and uppercase letters A through J are used in place of digits 0 through 9 in the encoding character set. The mangling then consists of an ``00`` followed by the run length of the encoded string and the encoded string itself. For example, the identifier ``vergüenza`` is mangled to ``0012vergenza_JFa``. (The encoding in standard Punycode would be ``vergenza-95a``) If the encoded string starts with a digit or an ``_``, an additional ``_`` is inserted between the run length and the encoded string. :: identifier ::= identifier 'o' OPERATOR-FIXITY OPERATOR-FIXITY ::= 'p' // prefix operator OPERATOR-FIXITY ::= 'P' // postfix operator OPERATOR-FIXITY ::= 'i' // infix operator OPERATOR-CHAR ::= 'a' // & 'and' OPERATOR-CHAR ::= 'c' // @ 'commercial at' OPERATOR-CHAR ::= 'd' // / 'divide' OPERATOR-CHAR ::= 'e' // = 'equals' OPERATOR-CHAR ::= 'g' // > 'greater' OPERATOR-CHAR ::= 'l' // < 'less' OPERATOR-CHAR ::= 'm' // * 'multiply' OPERATOR-CHAR ::= 'n' // ! 'not' OPERATOR-CHAR ::= 'o' // | 'or' OPERATOR-CHAR ::= 'p' // + 'plus' OPERATOR-CHAR ::= 'q' // ? 'question' OPERATOR-CHAR ::= 'r' // % 'remainder' OPERATOR-CHAR ::= 's' // - 'subtract' OPERATOR-CHAR ::= 't' // ~ 'tilde' OPERATOR-CHAR ::= 'x' // ^ 'xor' OPERATOR-CHAR ::= 'z' // . 'zperiod' If an identifier is followed by an ``o`` its text is interpreted as an operator. Each lowercase character maps to an operator character (``OPERATOR-CHAR``). Operators that contain non-ASCII characters are mangled by first mapping the ASCII operator characters to letters as for pure ASCII operator names, then Punycode-encoding the substituted string. For example, the infix operator ``«+»`` is mangled to ``007p_qcaDcoi`` (``p_qcaDc`` being the encoding of the substituted string ``«p»``). Substitutions ~~~~~~~~~~~~~ :: substitution ::= 'A' INDEX // substitution of N+26 substitution ::= 'A' SUBST-IDX* LAST-SUBST-IDX // One or more consecutive substitutions of N < 26 SUBST-IDX ::= [a-z] SUBST-IDX ::= NATURAL [a-z] LAST-SUBST-IDX ::= [A-Z] LAST-SUBST-IDX ::= NATURAL [A-Z] ```` is a back-reference to a previously mangled entity. The mangling algorithm maintains a mapping of entities to substitution indices as it runs. When an entity that can be represented by a substitution (a module, nominal type, or protocol) is mangled, a substitution is first looked for in the substitution map, and if it is present, the entity is mangled using the associated substitution index. Otherwise, the entity is mangled normally, and it is then added to the substitution map and associated with the next available substitution index. For example, in mangling a function type ``(zim.zang.zung, zim.zang.zung, zim.zippity) -> zim.zang.zoo`` (with module ``zim`` and class ``zim.zang``), the recurring contexts ``zim``, ``zim.zang``, and ``zim.zang.zung`` will be mangled using substitutions after being mangled for the first time. The first argument type will mangle in long form, ``3zim4zang4zung``, and in doing so, ``zim`` will acquire substitution ``AA``, ``zim.zang`` will acquire substitution ``AB``, and ``zim.zang.zung`` will acquire ``AC``. The second argument is the same as the first and will mangle using its substitution, ``AC``. The third argument type will mangle using the substitution for ``zim``, ``AA7zippity``. (It also acquires substitution ``AD`` which would be used if it mangled again.) The result type will mangle using the substitution for ``zim.zang``, ``AB3zoo`` (and acquire substitution ``AE``). There are some pre-defined substitutions, see ``KNOWN-TYPE-KIND``. If the mangling contains two or more consecutive substitutions, it can be abbreviated with the ``A`` substitution. Similar to word-substitutions the index is encoded as letters, whereas the last letter is uppercase:: AaeB // equivalent to A_A4_A0_ Repeated substitutions are encoded with a natural prefix number:: A3a2B // equivalent to AaaabB Numbers and Indexes ~~~~~~~~~~~~~~~~~~~ :: INDEX ::= '_' // 0 INDEX ::= NATURAL '_' // N+1 NATURAL ::= [1-9] [0-9]* NATURAL-ZERO ::= [0-9]+ ```` is a production for encoding numbers in contexts that can't end in a digit; it's optimized for encoding smaller numbers. :: INDEX-SUBSET ::= [SU]+ ```` is encoded like a bit vector and is optimized for encoding indices with a small upper bound. Function Specializations ~~~~~~~~~~~~~~~~~~~~~~~~ :: specialization ::= type '_' type* 'T' dropped-arg* 'g' SPEC-INFO // Generic re-abstracted specialization specialization ::= type '_' type* 'T' dropped-arg* 'B' SPEC-INFO // Alternative mangling for generic re-abstracted specializations, // used for functions with re-abstracted resilient parameter types. specialization ::= type '_' type* 'T' dropped-arg* 'G' SPEC-INFO // Generic not re-abstracted specialization specialization ::= type '_' type* 'Ts' SPEC-INFO // Generic re-abstracted prespecialization specialization ::= type '_' type* 'Ti' SPEC-INFO // Inlined function with generic substitutions. specialization ::= type '_' type* 'Ta' SPEC-INFO // Non-async specialization dropped-arg ::= 't' // The first argument is dropped dropped-arg ::= 't' NATURAL // The `N+1`th argument is dropped The types are the replacement types of the substitution list. :: specialization ::= type 'Tp' SPEC-INFO // Partial generic specialization specialization ::= type 'TP' SPEC-INFO // Partial generic specialization, not re-abstracted The type is the function type of the specialized function. :: specialization ::= spec-arg* 'Tf' SPEC-INFO ARG-SPEC-KIND* '_' ARG-SPEC-KIND // Function signature specialization kind The ```` describes how arguments are specialized. Some kinds need arguments, which precede ``Tf``. :: spec-arg ::= identifier spec-arg ::= type SPEC-INFO ::= FRAGILE? ASYNC-REMOVED? PASSID PASSID ::= '0' // AllocBoxToStack, PASSID ::= '1' // ClosureSpecializer, PASSID ::= '2' // CapturePromotion, PASSID ::= '3' // CapturePropagation, PASSID ::= '4' // FunctionSignatureOpts, PASSID ::= '5' // GenericSpecializer, PASSID ::= '6' // MoveDiagnosticInOutToOut, PASSID ::= '7' // AsyncDemotion, FRAGILE ::= 'q' ASYNC-REMOVED ::= 'a' // async effect removed ARG-SPEC-KIND ::= 'n' // Unmodified argument ARG-SPEC-KIND ::= 'c' // Consumes n 'type' arguments which are closed over types in argument order // and one 'identifier' argument which is the closure symbol name ARG-SPEC-KIND ::= 'p' CONST-PROP // Constant propagated argument ARG-SPEC-KIND ::= 'e' 'D'? 'G'? 'X'? // Generic argument, with optional dead, owned=>guaranteed or exploded-specifier ARG-SPEC-KIND ::= 'd' 'G'? 'X'? // Dead argument, with optional owned=>guaranteed or exploded-specifier ARG-SPEC-KIND ::= 'g' 'X'? // Owned => Guaranteed,, with optional exploded-specifier ARG-SPEC-KIND ::= 'x' // Exploded ARG-SPEC-KIND ::= 'i' // Box to value ARG-SPEC-KIND ::= 's' // Box to stack CONST-PROP ::= 'f' // Consumes one identifier argument which is a function symbol name CONST-PROP ::= 'g' // Consumes one identifier argument which is a global symbol name CONST-PROP ::= 'i' NATURAL-ZERO // 64-bit-integer CONST-PROP ::= 'd' NATURAL-ZERO // float-as-64-bit-integer CONST-PROP ::= 's' ENCODING // string literal. Consumes one identifier argument. CONST-PROP ::= 'k' // keypath. Consumes one identifier - the SHA1 of the keypath and two types (root and value). ENCODING ::= 'b' // utf8 ENCODING ::= 'w' // utf16 ENCODING ::= 'c' // objc If the first character of the string literal is a digit ``[0-9]`` or an underscore ``_``, the identifier for the string literal is prefixed with an additional underscore ``_``. Conventions for foreign symbols ------------------------------- Swift interoperates with multiple other languages - C, C++, Objective-C, and Objective-C++. Each of these languages defines their own mangling conventions, so Swift must take care to follow them. However, these conventions do not cover Swift-specific symbols like Swift type metadata for foreign types, so Swift uses its own mangling scheme for those symbols. Importing C and C++ structs ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Types imported from C and C++ are imported as if they are located in the ``__C`` module, regardless of the actual Clang module that they are coming from. This can be observed when mangling a Swift function that accepts a C/C++ struct as a parameter: C++ module ``CxxStructModule``: .. code-block:: c++ struct CxxStruct {}; inline void cxxFunction(CxxStruct s) {} Swift module ``main`` that imports ``CxxStructModule``: .. code-block:: swift import CxxStructModule public func swiftFunction(_ s: CxxStruct) {} Resulting symbols (showing only Itanium-mangled C++ symbols for brevity): .. code:: _Z11cxxFunction9CxxStruct // -> cxxFunction(CxxStruct) s4main13swiftFunctionyySo9CxxStructVF // -> main.swiftFunction(__C.CxxStruct) -> () The reason for ignoring the Clang module and always putting C and C++ types into ``__C`` at the Swift ABI level is that the Clang module is not a part of the C or C++ ABI. When owners of C and C++ Clang modules decide what changes are ABI-compatible or not, they will likely take into account C and C++ ABI, but not the Swift ABI. Therefore, Swift ABI can only encode information about a C or C++ type that the C and C++ ABI already encodes in order to remain compatible with future versions of libraries that evolve according to C and C++ ABI compatibility principles. The C/C++ compiler does not generate Swift metadata symbols and value witness tables for C and C++ types. To make a foreign type usable in Swift in the same way as a native type, the Swift compiler must generate these symbols. Specifically, each Swift module that uses a given C or C++ type generates the necessary Swift symbols. For the example above the Swift compiler will generate following nominal type descriptor symbol for ``CxxStruct`` while compiling the ``main`` module: .. code:: sSo9CxxStructVMn // -> nominal type descriptor for __C.CxxStruct Importing C++ class template instantiations ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A class template instantiation is imported as a struct named ``__CxxTemplateInst`` plus Itanium mangled type of the instantiation (see the ``type`` production in the Itanium specification). Note that Itanium mangling is used on all platforms, regardless of the ABI of the C++ toolchain, to ensure that the mangled name is a valid Swift type name (this is not the case for MSVC mangled names). A prefix with a double underscore (to ensure we have a reserved C++ identifier) is added to limit the possibility for conflicts with names of user-defined structs. The struct is notionally defined in the ``__C`` module, similarly to regular C and C++ structs and classes. Consider the following C++ module: .. code-block:: c++ template struct MagicWrapper { T t; }; struct MagicNumber {}; typedef MagicWrapper WrappedMagicNumber; ``WrappedMagicNumber`` is imported as a typealias for struct ``__CxxTemplateInst12MagicWrapperI11MagicNumberE``. Interface of the imported module looks as follows: .. code-block:: swift struct __CxxTemplateInst12MagicWrapperI11MagicNumberE { var t: MagicNumber } struct MagicNumber {} typealias WrappedMagicNumber = __CxxTemplateInst12MagicWrapperI11MagicNumberE