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Sema: Narrow down the derivation of == for RawRepresentable enums to non-resilient modules #40382

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merged 1 commit into from
Dec 3, 2021
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Sema: Narrow down the derivation of == for RawRepresentable enums to non-resilient modules #40382

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37 changes: 24 additions & 13 deletions lib/Sema/TypeCheckProtocol.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4123,6 +4123,11 @@ void ConformanceChecker::checkNonFinalClassWitness(ValueDecl *requirement,
}
}

static bool isSwiftRawRepresentableEnum(Type adoptee) {
auto *enumDecl = dyn_cast<EnumDecl>(adoptee->getAnyNominal());
return (enumDecl && enumDecl->hasRawType() && !enumDecl->isObjC());
}

// If the given witness matches a generic RawRepresentable function conforming
// with a given protocol e.g. `func == <T : RawRepresentable>(lhs: T, rhs: T) ->
// Bool where T.RawValue : Equatable`
Expand Down Expand Up @@ -4201,13 +4206,8 @@ ConformanceChecker::resolveWitnessViaLookup(ValueDecl *requirement) {
!requirement->getAttrs().isUnavailable(getASTContext());

auto &ctx = getASTContext();
bool isEquatableConformance = Conformance->getProtocol() ==
ctx.getProtocol(KnownProtocolKind::Equatable);

auto decl = Conformance->getDeclContext()->getSelfNominalTypeDecl();
auto *enumDecl = dyn_cast_or_null<EnumDecl>(decl);
bool isSwiftRawRepresentableEnum =
enumDecl && enumDecl->hasRawType() && !enumDecl->isObjC();
bool isEquatableConformance = (Conformance->getProtocol() ==
ctx.getProtocol(KnownProtocolKind::Equatable));

if (findBestWitness(requirement,
considerRenames ? &ignoringNames : nullptr,
Expand All @@ -4217,12 +4217,23 @@ ConformanceChecker::resolveWitnessViaLookup(ValueDecl *requirement) {
const auto &best = matches[bestIdx];
auto witness = best.Witness;

if (canDerive && isSwiftRawRepresentableEnum && isEquatableConformance) {
// For swift enum types that can derive equatable conformance,
// if the best witness is default generic conditional conforming
// `func == <T : RawRepresentable>(lhs: T, rhs: T) -> Bool where
// T.RawValue : Equatable` let's return as missing and derive
// the conformance since it is possible.
if (canDerive &&
isEquatableConformance &&
isSwiftRawRepresentableEnum(Adoptee) &&
!Conformance->getDeclContext()->getParentModule()->isResilient()) {
// For swift enum types that can derive an Equatable conformance,
// if the best witness is the default implementation
//
// func == <T : RawRepresentable>(lhs: T, rhs: T) -> Bool
// where T.RawValue : Equatable
//
// let's return as missing and derive the conformance, since it will be
// more efficient than comparing rawValues.
//
// However, we only do this if the module is non-resilient. If it is
// resilient, this change can break ABI by publishing a synthesized ==
// declaration that may not exist in versions of the framework built
// with an older compiler.
if (isRawRepresentableGenericFunction(ctx, witness, Conformance)) {
return ResolveWitnessResult::Missing;
}
Expand Down
63 changes: 36 additions & 27 deletions test/SILGen/enum_equatable_witness.swift
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Original file line number Diff line number Diff line change
@@ -1,70 +1,79 @@
// RUN: %target-swift-emit-silgen -module-name main %s -verify | %FileCheck %s
// RUN: %target-swift-emit-silgen -module-name main %s -verify | %FileCheck %s --check-prefix=FRAGILE
// RUN: %target-swift-emit-silgen -module-name main %s -verify -enable-library-evolution | %FileCheck %s --check-prefix=RESILIENT

// SR-9425
enum MyState : String {
public enum MyState : String {
case closed = "closed"
case opened = "opened"
}

@inline(never)
func check_state(_ state : MyState) -> Int {
// CHECK: function_ref @$s4main7MyStateO21__derived_enum_equalsySbAC_ACtFZ
// CHECK-LABEL: sil [ossa] @$s4main11check_stateySiAA7MyStateOF : $@convention(thin) (MyState) -> Int {
public func check_state(_ state : MyState) -> Int {
// FRAGILE: function_ref @$s4main7MyStateO21__derived_enum_equalsySbAC_ACtFZ
// RESILIENT: function_ref @$ss2eeoiySbx_xtSYRzSQ8RawValueRpzlF
return state == .opened ? 1 : 0
}

// generic-enum.swift
enum GenericMyState<T> : String {
public enum GenericMyState<T> : String {
case closed
case opened
}

@inline(never)
func check_generic_state(_ state : GenericMyState<Int>) -> Int {
// CHECK: function_ref @$s4main14GenericMyStateO21__derived_enum_equalsySbACyxG_AEtFZ
// CHECK-LABEL: sil [ossa] @$s4main19check_generic_stateySiAA14GenericMyStateOySiGF : $@convention(thin) (GenericMyState<Int>) -> Int {
public func check_generic_state(_ state : GenericMyState<Int>) -> Int {
// FRAGILE: function_ref @$s4main14GenericMyStateO21__derived_enum_equalsySbACyxG_AEtFZ
// RESILIENT: function_ref @$ss2eeoiySbx_xtSYRzSQ8RawValueRpzlF
return state == .opened ? 1 : 0
}

// regular-enum.swift
enum Regular {
public enum Regular {
case closed
case opened
}

@inline(never)
func check_regular(_ state : Regular) -> Int {
// CHECK: function_ref @$s4main7RegularO21__derived_enum_equalsySbAC_ACtFZ
// CHECK-LABEL: sil [ossa] @$s4main13check_regularySiAA7RegularOF : $@convention(thin) (Regular) -> Int {
public func check_regular(_ state : Regular) -> Int {
// FRAGILE: function_ref @$s4main7RegularO21__derived_enum_equalsySbAC_ACtFZ
// RESILIENT: function_ref @$ss2eeoiySbx_xtSYRzSQ8RawValueRpzlF
return state == .closed ? 1 : 0
}

// string-enum.swift
enum Alphabet : String {
public enum Alphabet : String {
case A = "A", B = "B", C = "C", D = "D", E = "E", F = "F", G = "G", H = "H", I = "I", J = "J"
}

@inline(never)
func check_alphabet(_ state : Alphabet) -> Int {
// CHECK: function_ref @$s4main8AlphabetO21__derived_enum_equalsySbAC_ACtFZ
// CHECK-LABEL: sil [ossa] @$s4main14check_alphabetySiAA8AlphabetOF : $@convention(thin) (Alphabet) -> Int {
public func check_alphabet(_ state : Alphabet) -> Int {
// FRAGILE: function_ref @$s4main8AlphabetO21__derived_enum_equalsySbAC_ACtFZ
// RESILIENT: function_ref @$ss2eeoiySbx_xtSYRzSQ8RawValueRpzlF
return state == .E ? 1 : 0
}

@inline(never)
func compareIt(_ state : Alphabet, _ rhs: Alphabet) -> Bool {
// CHECK: function_ref @$s4main8AlphabetO21__derived_enum_equalsySbAC_ACtFZ
// CHECK-LABEL: sil [ossa] @$s4main9compareItySbAA8AlphabetO_ADtF : $@convention(thin) (Alphabet, Alphabet) -> Bool {
public func compareIt(_ state : Alphabet, _ rhs: Alphabet) -> Bool {
// FRAGILE: function_ref @$s4main8AlphabetO21__derived_enum_equalsySbAC_ACtFZ
// RESILIENT: function_ref @$ss2eeoiySbx_xtSYRzSQ8RawValueRpzlF
return state == rhs
}

// int-enum.swift
enum AlphabetInt : Int {
public enum AlphabetInt : Int {
case A = 10, B = 100, C = 12, D = 456, E = 1, F = 3, G = 77, H = 2, I = 27, J = 42
}

@inline(never)
func check_alphabet_int(_ state : AlphabetInt) -> Int {
// CHECK: function_ref @$s4main11AlphabetIntO21__derived_enum_equalsySbAC_ACtFZ
// CHECK-LABEL: sil [ossa] @$s4main18check_alphabet_intySiAA11AlphabetIntOF : $@convention(thin) (AlphabetInt) -> Int {
public func check_alphabet_int(_ state : AlphabetInt) -> Int {
// FRAGILE: function_ref @$s4main11AlphabetIntO21__derived_enum_equalsySbAC_ACtFZ
// RESILIENT: function_ref @$ss2eeoiySbx_xtSYRzSQ8RawValueRpzlF
return state == .E ? 1 : 0
}

@inline(never)
func compareIt(_ state : AlphabetInt, _ rhs: AlphabetInt) -> Bool {
// CHECK: function_ref @$s4main11AlphabetIntO21__derived_enum_equalsySbAC_ACtFZ
// CHECK-LABEL: sil [ossa] @$s4main9compareItySbAA11AlphabetIntO_ADtF : $@convention(thin) (AlphabetInt, AlphabetInt) -> Bool {
public func compareIt(_ state : AlphabetInt, _ rhs: AlphabetInt) -> Bool {
// FRAGILE: function_ref @$s4main11AlphabetIntO21__derived_enum_equalsySbAC_ACtFZ
// RESILIENT: function_ref @$ss2eeoiySbx_xtSYRzSQ8RawValueRpzlF
return state == rhs
}