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Sema: Enable exportability checks in non-library-evolution mode as warnings by default #86335

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Merged
xymus merged 7 commits into from
Jan 22, 2026
Merged

Sema: Enable exportability checks in non-library-evolution mode as warnings by default #86335

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2c59e8c
Sema: Check exportability in non-library-evolution as warnings by def…
xymus Dec 16, 2025
fa9d852
Sema: Stop downgrading to private enums cases and destructors with er…
xymus Dec 22, 2025
5cc4c78
Sema: Update warning on `@_implementationOnly` import
xymus Dec 6, 2025
2d5b4bb
Diagnostics: Intro `limitBehaviorIfMorePermissive`
xymus Jan 8, 2026
8ab9047
Sema: Downgrade more exportability diags to warning by default
xymus Jan 8, 2026
974e61d
Sema: Loosen exportability checking for non-publicly imported types
xymus Jan 12, 2026
9d4ed92
AST: Only check availability of explicitly exported decls
xymus Jan 7, 2026
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6 changes: 6 additions & 0 deletions include/swift/AST/DiagnosticEngine.h
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Expand Up @@ -364,6 +364,12 @@ namespace swift {
/// emitted as a warning, but a note will still be emitted as a note.
InFlightDiagnostic &limitBehavior(DiagnosticBehavior limit);

/// Prevent the diagnostic from behaving more severely than \p limit or the
/// previously set limit. Use to compose conditions to downgrade a
/// diagnostic in succession.
InFlightDiagnostic
&limitBehaviorIfMorePermissive(DiagnosticBehavior limit);

/// Conditionally prevent the diagnostic from behaving more severely than \p
/// limit. If the condition is false, no limit is imposed.
InFlightDiagnostic &limitBehaviorIf(bool shouldLimit,
Expand Down
5 changes: 3 additions & 2 deletions include/swift/AST/DiagnosticsSema.def
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Expand Up @@ -1272,8 +1272,9 @@ ERROR(module_not_compiled_with_library_evolution,none,
(Identifier, Identifier))
GROUPED_WARNING(implementation_only_requires_library_evolution,
ImplementationOnlyDeprecated,none,
"using '@_implementationOnly' without enabling library evolution "
"for %0 may lead to instability during execution",
"safely use '@_implementationOnly' without library evolution "
"by setting '-enable-experimental-feature CheckImplementationOnly' "
"for %0",
(Identifier))
GROUPED_WARNING(implementation_only_deprecated,
ImplementationOnlyDeprecated,none,
Expand Down
20 changes: 8 additions & 12 deletions lib/AST/AccessRequests.cpp
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Expand Up @@ -104,19 +104,15 @@ AccessLevelRequest::evaluate(Evaluator &evaluator, ValueDecl *D) const {
// Special case for dtors and enum elements: inherit from container
if (D->getKind() == DeclKind::Destructor ||
D->getKind() == DeclKind::EnumElement) {
if (D->hasInterfaceType() && D->isInvalid()) {
return AccessLevel::Private;
} else {
auto container = dyn_cast<NominalTypeDecl>(DC);
if (D->getKind() == DeclKind::Destructor && !container) {
// A destructor in an extension means @_objcImplementation. An
// @_objcImplementation class's deinit is only called by the ObjC thunk,
// if at all, so it is nonpublic.
return AccessLevel::Internal;
}

return std::max(container->getFormalAccess(), AccessLevel::Internal);
auto container = dyn_cast<NominalTypeDecl>(DC);
if (D->getKind() == DeclKind::Destructor && !container) {
// A destructor in an extension means @_objcImplementation. An
// @_objcImplementation class's deinit is only called by the ObjC thunk,
// if at all, so it is nonpublic.
return AccessLevel::Internal;
}

return std::max(container->getFormalAccess(), AccessLevel::Internal);
}

switch (DC->getContextKind()) {
Expand Down
4 changes: 1 addition & 3 deletions lib/AST/Availability.cpp
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Expand Up @@ -1014,8 +1014,6 @@ ExportedLevel swift::isExported(const ValueDecl *VD) {

// Is this a type exposed by default in a non-resilient module?
if (isa<NominalTypeDecl>(VD) &&
VD->getASTContext().LangOpts.hasFeature(
Feature::CheckImplementationOnly) &&
VD->getDeclContext()->getParentModule()->getResilienceStrategy() !=
ResilienceStrategy::Resilient &&
!VD->getAttrs().hasAttribute<ImplementationOnlyAttr>())
Expand Down Expand Up @@ -1064,5 +1062,5 @@ ExportedLevel swift::isExported(const ExtensionDecl *ED) {
for (const Decl *D : ED->getMembers())
membersExported = std::max(membersExported, isExported(D));

return membersExported;
return std::min(exported, membersExported);
}
2 changes: 1 addition & 1 deletion lib/AST/AvailabilityScopeBuilder.cpp
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Expand Up @@ -479,7 +479,7 @@ class AvailabilityScopeBuilder : private ASTWalker {
if (decl->isSPI())
return true;

return isExported(decl) == ExportedLevel::None;
return isExported(decl) != ExportedLevel::Exported;
}

/// Returns the source range which should be refined by declaration. This
Expand Down
3 changes: 1 addition & 2 deletions lib/AST/Decl.cpp
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Expand Up @@ -2808,8 +2808,7 @@ ExportedLevel VarDecl::isLayoutExposedToClients() const {
return ExportedLevel::None;

auto M = getDeclContext()->getParentModule();
if (getASTContext().LangOpts.hasFeature(Feature::CheckImplementationOnly) &&
M->getResilienceStrategy() != ResilienceStrategy::Resilient) {
if (M->getResilienceStrategy() != ResilienceStrategy::Resilient) {
// Non-resilient module expose layouts by default.
return ExportedLevel::ImplicitlyExported;
} else {
Expand Down
7 changes: 7 additions & 0 deletions lib/AST/DiagnosticEngine.cpp
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Expand Up @@ -458,6 +458,13 @@ InFlightDiagnostic::limitBehavior(DiagnosticBehavior limit) {
return *this;
}

InFlightDiagnostic &
InFlightDiagnostic::limitBehaviorIfMorePermissive(DiagnosticBehavior limit) {
auto prev = getDiag().getBehaviorLimit();
getDiag().setBehaviorLimit(prev.merge(limit));
return *this;
}

InFlightDiagnostic &
InFlightDiagnostic::limitBehaviorUntilLanguageMode(DiagnosticBehavior limit,
unsigned majorVersion) {
Expand Down
4 changes: 2 additions & 2 deletions lib/Sema/ImportResolution.cpp
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Expand Up @@ -929,8 +929,8 @@ void UnboundImport::validateResilience(NullablePtr<ModuleDecl> topLevelModule,
diag::implementation_only_deprecated);
inFlight.fixItReplace(import.implementationOnlyRange, "internal");
}
} else if ( // Non-resilient client
!shouldSuppressNonResilientImplementationOnlyImportDiagnostic(
} else if (!ctx.LangOpts.hasFeature(Feature::CheckImplementationOnly) &&
!shouldSuppressNonResilientImplementationOnlyImportDiagnostic(
targetName.str(), importerName.str())) {
ctx.Diags.diagnose(import.importLoc,
diag::implementation_only_requires_library_evolution,
Expand Down
39 changes: 23 additions & 16 deletions lib/Sema/ResilienceDiagnostics.cpp
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Expand Up @@ -175,7 +175,8 @@ static bool diagnoseTypeAliasDeclRefExportability(SourceLoc loc,
auto ignoredDowngradeToWarning = DowngradeToWarning::No;
auto originKind =
getDisallowedOriginKind(D, where, ignoredDowngradeToWarning);
if (where.canReferenceOrigin(originKind))
auto commonBehavior = where.behaviorForReferenceToOrigin(originKind);
if (commonBehavior == DiagnosticBehavior::Ignore)
return false;

// As an exception, if the import of the module that defines the desugared
Expand All @@ -197,15 +198,17 @@ static bool diagnoseTypeAliasDeclRefExportability(SourceLoc loc,
TAD, definingModule->getNameStr(), D->getNameStr(),
static_cast<unsigned>(*reason), definingModule->getName(),
static_cast<unsigned>(originKind))
.warnUntilLanguageModeIf(warnPreSwift6, 6);
.warnUntilLanguageModeIf(warnPreSwift6, 6)
.limitBehaviorIfMorePermissive(commonBehavior);
} else {
ctx.Diags
.diagnose(loc,
diag::inlinable_typealias_desugars_to_type_from_hidden_module,
TAD, definingModule->getNameStr(), D->getNameStr(),
fragileKind.getSelector(), definingModule->getName(),
static_cast<unsigned>(originKind))
.warnUntilLanguageModeIf(warnPreSwift6, 6);
.warnUntilLanguageModeIf(warnPreSwift6, 6)
.limitBehaviorIfMorePermissive(commonBehavior);
}
D->diagnose(diag::kind_declared_here, DescriptiveDeclKind::Type);

Expand Down Expand Up @@ -249,7 +252,13 @@ static bool shouldDiagnoseDeclAccess(const ValueDecl *D,
switch (*reason) {
case ExportabilityReason::ExtensionWithPublicMembers:
case ExportabilityReason::ExtensionWithConditionalConformances:
return true;
// Allow public members in extensions of implicitly exported types.
// Extensions cannot define stored variables avoiding the memory layout
// concerns and we don't print swiftinterfaces in non-library-evolution
// mode.
// We should be able to always allow this if it's correctly guarded
// at generating module interfaces and generated headers.
return where.getExportedLevel() == ExportedLevel::Exported;
case ExportabilityReason::Inheritance:
case ExportabilityReason::ImplicitlyPublicInheritance:
return isa<ProtocolDecl>(D);
Expand Down Expand Up @@ -301,7 +310,8 @@ static bool diagnoseValueDeclRefExportability(SourceLoc loc, const ValueDecl *D,
}
});

if (where.canReferenceOrigin(originKind))
auto commonBehavior = where.behaviorForReferenceToOrigin(originKind);
if (commonBehavior == DiagnosticBehavior::Ignore)
return false;

auto fragileKind = where.getFragileFunctionKind();
Expand Down Expand Up @@ -361,21 +371,16 @@ static bool diagnoseValueDeclRefExportability(SourceLoc loc, const ValueDecl *D,
static_cast<unsigned>(*reason),
definingModule->getName(),
static_cast<unsigned>(originKind))
.limitBehavior(limit);
.limitBehavior(limit.merge(commonBehavior));

D->diagnose(diag::kind_declared_here, D->getDescriptiveKind());
} else {
// Only implicitly imported decls should be reported as a warning,
// and only for language versions below Swift 6.
assert(downgradeToWarning == DowngradeToWarning::No ||
originKind == DisallowedOriginKind::MissingImport &&
"Only implicitly imported decls should be reported as a warning.");

ctx.Diags.diagnose(loc, diag::inlinable_decl_ref_from_hidden_module, D,
fragileKind.getSelector(), definingModule->getName(),
static_cast<unsigned>(originKind))
.warnUntilLanguageModeIf(downgradeToWarning == DowngradeToWarning::Yes,
6);
6)
.limitBehaviorIfMorePermissive(commonBehavior);

if (originKind == DisallowedOriginKind::MissingImport &&
downgradeToWarning == DowngradeToWarning::Yes)
Expand Down Expand Up @@ -447,7 +452,8 @@ TypeChecker::diagnoseConformanceExportability(SourceLoc loc,
});

auto originKind = getDisallowedOriginKind(ext, where);
if (where.canReferenceOrigin(originKind))
auto commonBehavior = where.behaviorForReferenceToOrigin(originKind);
if (commonBehavior == DiagnosticBehavior::Ignore)
return false;

auto reason = where.getExportabilityReason();
Expand All @@ -463,8 +469,9 @@ TypeChecker::diagnoseConformanceExportability(SourceLoc loc,
(warnIfConformanceUnavailablePreSwift6 &&
originKind != DisallowedOriginKind::SPIOnly &&
originKind != DisallowedOriginKind::NonPublicImport) ||
originKind == DisallowedOriginKind::MissingImport,
6);
originKind == DisallowedOriginKind::MissingImport,
6)
.limitBehaviorIfMorePermissive(commonBehavior);

if (!ctx.LangOpts.hasFeature(Feature::StrictAccessControl) &&
originKind == DisallowedOriginKind::MissingImport &&
Expand Down
2 changes: 0 additions & 2 deletions lib/Sema/TypeCheckAccess.cpp
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Expand Up @@ -2169,8 +2169,6 @@ swift::getDisallowedOriginKind(const Decl *decl,

// Implementation-only memory layouts for non-library-evolution mode.
if (isa<NominalTypeDecl>(decl) &&
Context.LangOpts.hasFeature(
Feature::CheckImplementationOnly) &&
decl->getAttrs().hasAttribute<ImplementationOnlyAttr>())
return DisallowedOriginKind::ImplementationOnlyMemoryLayout;

Expand Down
19 changes: 15 additions & 4 deletions lib/Sema/TypeCheckAvailability.cpp
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Expand Up @@ -236,9 +236,11 @@ bool ExportContext::mustOnlyReferenceExportedDecls() const {
return Exported || FragileKind.kind != FragileFunctionKind::None;
}

bool ExportContext::canReferenceOrigin(DisallowedOriginKind originKind) const {
DiagnosticBehavior
ExportContext::behaviorForReferenceToOrigin(DisallowedOriginKind originKind)
const {
if (originKind == DisallowedOriginKind::None)
return true;
return DiagnosticBehavior::Ignore;

// Exportability checks for non-library-evolution mode have less restrictions
// than the library-evolution ones. Implicitly always emit into client code
Expand All @@ -253,7 +255,7 @@ bool ExportContext::canReferenceOrigin(DisallowedOriginKind originKind) const {
case DisallowedOriginKind::SPIOnly:
case DisallowedOriginKind::SPIImported:
case DisallowedOriginKind::SPILocal:
return true;
return DiagnosticBehavior::Ignore;
case DisallowedOriginKind::MissingImport:
case DisallowedOriginKind::InternalBridgingHeaderImport:
case DisallowedOriginKind::ImplementationOnly:
Expand All @@ -263,7 +265,16 @@ bool ExportContext::canReferenceOrigin(DisallowedOriginKind originKind) const {
}
}

return false;
// Exportability checking for non-library-evolution was introduced late,
// downgrade errors to warnings by default.
auto &ctx = DC->getASTContext();
if (getExportedLevel() == ExportedLevel::ImplicitlyExported &&
originKind != DisallowedOriginKind::ImplementationOnlyMemoryLayout &&
!ctx.LangOpts.hasFeature(Feature::CheckImplementationOnly) &&
!ctx.isLanguageModeAtLeast(7))
return DiagnosticBehavior::Warning;

return DiagnosticBehavior::Error;
}

std::optional<ExportabilityReason>
Expand Down
7 changes: 4 additions & 3 deletions lib/Sema/TypeCheckAvailability.h
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Expand Up @@ -202,9 +202,10 @@ class ExportContext {
/// because it is the function body context of an inlinable function.
bool mustOnlyReferenceExportedDecls() const;

/// If true, the context reference a dependency of \p originKind without
/// restriction.
bool canReferenceOrigin(DisallowedOriginKind originKind) const;
/// Level of restriction to references from the context to an \p originKind.
/// This check is shared by different diagnostics.
DiagnosticBehavior
behaviorForReferenceToOrigin(DisallowedOriginKind originKind) const;

/// Get the ExportabilityReason for diagnostics. If this is 'None', there
/// are no restrictions on referencing unexported declarations.
Expand Down
2 changes: 1 addition & 1 deletion test/Index/enum_case_with_invalid_associated_type.swift
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@@ -1,7 +1,7 @@
enum MyEnum {
// RUN: %target-swift-ide-test -print-indexed-symbols -source-filename %s | %FileCheck %s
case test(artifactID: String, hostTriple: Triple)
// CHECK: enumerator(less_than_private)/Swift | test(artifactID:hostTriple:)
// CHECK: enumerator(internal)/Swift | test(artifactID:hostTriple:)
// CHECK: param/Swift | artifactID
// CHECK: param/Swift | hostTriple
}
6 changes: 3 additions & 3 deletions test/Sema/access-level-and-implementation-only-import-embedded.swift
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Expand Up @@ -18,7 +18,7 @@
// REQUIRES: embedded_stdlib_cross_compiling

@_implementationOnly internal import directs
// expected-warning @-1 {{using '@_implementationOnly' without enabling library evolution for 'main' may lead to instability during execution}}
// expected-warning @-1 {{safely use '@_implementationOnly' without library evolution by setting '-enable-experimental-feature CheckImplementationOnly' for 'main'}}
// expected-note @-2 11 {{struct 'StructFromDirect' imported as 'internal' from 'directs' here}}
// expected-note @-3 6 {{initializer 'init()' imported as 'internal' from 'directs' here}}
import indirects
Expand Down Expand Up @@ -174,9 +174,9 @@ public struct ExposedLayoutPublic {
// expected-error @-1 {{cannot use struct 'StructFromDirect' in a property declaration marked public or in a '@frozen' or '@usableFromInline' context; 'directs' has been imported as implementation-only}}
// expected-note @-2 {{struct 'StructFromDirect' is imported by this file as 'internal' from 'directs'}}

private var privateField: StructFromDirect
private var privateField: StructFromDirect // expected-warning {{cannot use struct 'StructFromDirect' in a property declaration member of a type not marked '@_implementationOnly'; 'directs' has been imported as implementation-only}}
}

private struct ExposedLayoutPrivate {
private var privateField: StructFromDirect
private var privateField: StructFromDirect // expected-warning {{cannot use struct 'StructFromDirect' in a property declaration member of a type not marked '@_implementationOnly'; 'directs' has been imported as implementation-only}}
}
43 changes: 35 additions & 8 deletions test/Sema/access-level-import-classic-exportability.swift
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@@ -1,30 +1,52 @@
// RUN: %empty-directory(%t)
// RUN: split-file --leading-lines %s %t

/// Build the libraries.
/// Non-library-evolution.
// RUN: %target-swift-frontend -emit-module %t/PublicLib.swift -o %t
// RUN: %target-swift-frontend -emit-module %t/PackageLib.swift -o %t
// RUN: %target-swift-frontend -emit-module %t/InternalLib.swift -o %t \
// RUN: -package-name pkg
// RUN: %target-swift-frontend -emit-module %t/FileprivateLib.swift -o %t
// RUN: %target-swift-frontend -emit-module %t/PrivateLib.swift -o %t

/// Check diagnostics.
// RUN: %target-swift-frontend -typecheck %t/Client.swift -I %t \
// RUN: -package-name pkg -swift-version 5 \
// RUN: -verify -verify-ignore-unrelated

/// CheckImplementationOnly doesn't change the results.
// RUN: %target-swift-frontend -typecheck %t/Client.swift -I %t \
// RUN: -package-name pkg -swift-version 5 \
// RUN: -enable-experimental-feature CheckImplementationOnly \
// RUN: -verify -verify-ignore-unrelated


/// Library-evolution.
// RUN: %target-swift-frontend -emit-module %t/PublicLib.swift -o %t \
// RUN: -enable-library-evolution
// RUN: %target-swift-frontend -emit-module %t/PackageLib.swift -o %t \
// RUN: -enable-library-evolution
// RUN: %target-swift-frontend -emit-module %t/InternalLib.swift -o %t \
// RUN: -enable-library-evolution
// RUN: -enable-library-evolution -package-name pkg
// RUN: %target-swift-frontend -emit-module %t/FileprivateLib.swift -o %t \
// RUN: -enable-library-evolution
// RUN: %target-swift-frontend -emit-module %t/PrivateLib.swift -o %t \
// RUN: -enable-library-evolution

/// Check diagnostics.
// RUN: %target-swift-frontend -typecheck %t/Client.swift -I %t \
// RUN: -package-name TestPackage -swift-version 5 \
// RUN: -enable-experimental-feature AccessLevelOnImport -verify -verify-ignore-unrelated
// RUN: -package-name pkg -swift-version 5 \
// RUN: -enable-library-evolution \
// RUN: -verify -verify-ignore-unrelated

/// Check diagnostics with library-evolution.
/// CheckImplementationOnly doesn't change the results.
// RUN: %target-swift-frontend -typecheck %t/Client.swift -I %t \
// RUN: -package-name TestPackage -swift-version 5 \
// RUN: -package-name pkg -swift-version 5 \
// RUN: -enable-library-evolution \
// RUN: -enable-experimental-feature AccessLevelOnImport -verify -verify-ignore-unrelated
// RUN: -enable-experimental-feature CheckImplementationOnly \
// RUN: -verify -verify-ignore-unrelated

// REQUIRES: swift_feature_AccessLevelOnImport
// REQUIRES: swift_feature_CheckImplementationOnly

//--- PublicLib.swift
public struct PublicImportType {
Expand All @@ -41,6 +63,8 @@ public struct InternalImportType {
public init() {}
}

package struct InternalImportPackageType {}

//--- FileprivateLib.swift
public struct FileprivateImportType {
public init() {}
Expand Down Expand Up @@ -141,6 +165,9 @@ extension Array: InternalConstrainedExtensionProtoInFileprivate where Element ==
extension InternalImportType {
fileprivate func fileprivateMethod() {}
}
extension InternalImportPackageType { // No error
public func foo() {}
}

private protocol InternalConstrainedExtensionProtoInPrivate {}
extension Array: InternalConstrainedExtensionProtoInPrivate where Element == InternalImportType {}
Expand Down
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