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IRGen: We can't look through opaque archetypes if the underlying type contains a private type #27609

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IRGen: We can't look through opaque archetypes if the underlying type contains a private type #27609

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40 changes: 30 additions & 10 deletions lib/IRGen/MetadataRequest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -512,15 +512,28 @@ CanType IRGenModule::getRuntimeReifiedType(CanType type) {
}));
}

static bool containsPrivateType(CanType ty) {
return ty.findIf([](Type t) -> bool {
if (auto *nominal = t->getAnyNominal()) {
if (nominal->getEffectiveAccess() <= AccessLevel::FilePrivate)
return true;
}
return false;
});
}

CanType IRGenModule::substOpaqueTypesWithUnderlyingTypes(CanType type) {
// Substitute away opaque types whose underlying types we're allowed to
// assume are constant.
if (type->hasOpaqueArchetype()) {
ReplaceOpaqueTypesWithUnderlyingTypes replacer(getSwiftModule(),
ResilienceExpansion::Maximal);
type = type.subst(replacer, replacer,
SubstFlags::SubstituteOpaqueArchetypes)
->getCanonicalType();
auto underlyingTy =
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Since you have an IRGenModule here, I think you should instead use getTypeInfo(type).isABIAccessible()

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isABIAccessible does not give the right answer for private non resilient types:

 /// Whether this type is known to be ABI-accessible, i.e. whether it's        
  /// actually possible to do ABI operations on it from this current SILModule. 
  /// See SILModule::isTypeABIAccessible.                                       
  ///                                                                           
  /// All fixed-size types are currently ABI-accessible, although this would    
  /// not be difficult to change (e.g. if we had an archetype size constraint   
  /// that didn't say anything about triviality).                               
  IsABIAccessible_t isABIAccessible() const {

The failure occurs when we build the associated type witness. The associated type resolves to an opaque type and the underlying type contains the private type.

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Ah, good point. In that case, I think it's still worth extracting a new predicate since it might come up elsewhere.

Is 'private' access enough though? It seems if the declaration is internal, you'll run into the same problem.

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You are right internal access is problematic across modules (the problematic case can happen with non-inlineable functions from non resilient modules).

I will fix the code in the ReplaceOpaqueTypesWithUnderlyingTypes utility instead.

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New PR: #27666

type.subst(replacer, replacer, SubstFlags::SubstituteOpaqueArchetypes)
->getCanonicalType();
// The underlying type could contain a private type from a different TU.
if (!containsPrivateType(underlyingTy))
return underlyingTy;
}

return type;
Expand All @@ -533,8 +546,12 @@ SILType IRGenModule::substOpaqueTypesWithUnderlyingTypes(
if (type.getASTType()->hasOpaqueArchetype()) {
ReplaceOpaqueTypesWithUnderlyingTypes replacer(getSwiftModule(),
ResilienceExpansion::Maximal);
type = type.subst(getSILModule(), replacer, replacer, genericSig,
/*substitute opaque*/ true);
auto underlyingTy =
type.subst(getSILModule(), replacer, replacer, genericSig,
/*substitute opaque*/ true);
// The underlying type could contain a private type from a different TU.
if (!containsPrivateType(underlyingTy.getASTType()))
return underlyingTy;
}

return type;
Expand All @@ -548,11 +565,14 @@ IRGenModule::substOpaqueTypesWithUnderlyingTypes(CanType type,
if (type->hasOpaqueArchetype()) {
ReplaceOpaqueTypesWithUnderlyingTypes replacer(getSwiftModule(),
ResilienceExpansion::Maximal);
conformance = conformance.subst(type, replacer, replacer,
SubstFlags::SubstituteOpaqueArchetypes);
type = type.subst(replacer, replacer,
SubstFlags::SubstituteOpaqueArchetypes)
->getCanonicalType();
auto substConformance = conformance.subst(
type, replacer, replacer, SubstFlags::SubstituteOpaqueArchetypes);
auto underlyingTy =
type.subst(replacer, replacer, SubstFlags::SubstituteOpaqueArchetypes)
->getCanonicalType();
// The underlying type could contain a private type from a different TU.
if (!containsPrivateType(underlyingTy))
return std::make_pair(underlyingTy, substConformance);
}

return std::make_pair(type, conformance);
Expand Down
17 changes: 17 additions & 0 deletions test/IRGen/Inputs/opaque_result_type_private_underlying_2.swift
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Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
public protocol A {
associatedtype Assoc
func bindAssoc() -> Assoc
}

public protocol Q {}

fileprivate struct PrivateS : Q {
init() {}
}

public struct G : A {
public init() {}
public func bindAssoc() -> some Q {
return PrivateS()
}
}
8 changes: 8 additions & 0 deletions test/IRGen/opaque_result_type_private_underlying.swift
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Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
// RUN: %target-swift-frontend -disable-availability-checking -emit-ir -primary-file %s -primary-file %S/Inputs/opaque_result_type_private_underlying_2.swift

public struct G2 : A {
public init() {}
public func bindAssoc() -> some Q {
return G().bindAssoc()
}
}