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[cxx-interop] Fix crashing on recursive enums #85980

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Merged
Xazax-hun merged 1 commit into from
Dec 12, 2025
+32 −2
Merged

[cxx-interop] Fix crashing on recursive enums #85980

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4 changes: 4 additions & 0 deletions lib/PrintAsClang/DeclAndTypePrinter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -15,10 +15,12 @@

#include "OutputLanguageMode.h"

#include "PrintClangFunction.h"
#include "swift/AST/Decl.h"
#include "swift/AST/Module.h"
#include "swift/AST/Type.h"
// for OptionalTypeKind
#include "swift/AST/TypeRepr.h"
#include "swift/ClangImporter/ClangImporter.h"
#include "llvm/ADT/StringSet.h"

Expand Down Expand Up @@ -56,6 +58,7 @@ class DeclAndTypePrinter {
private:
class Implementation;
friend class Implementation;
friend class DeclAndTypeClangFunctionPrinter;

ModuleDecl &M;
raw_ostream &os;
Expand All @@ -69,6 +72,7 @@ class DeclAndTypePrinter {
bool requiresExposedAttribute;
llvm::StringSet<> &exposedModules;
OutputLanguageMode outputLang;
llvm::DenseMap<Type, std::optional<ClangRepresentation>> typeRepresentations;

/// The name 'CFTypeRef'.
///
Expand Down
18 changes: 16 additions & 2 deletions lib/PrintAsClang/PrintClangFunction.cpp
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Expand Up @@ -1895,13 +1895,27 @@ ClangRepresentation DeclAndTypeClangFunctionPrinter::getTypeRepresentation(
PrimitiveTypeMapping &typeMapping,
SwiftToClangInteropContext &interopContext, DeclAndTypePrinter &declPrinter,
const ModuleDecl *emittedModule, Type ty) {
auto [it, inserted] = declPrinter.typeRepresentations.try_emplace(ty);
// If we already seen the type but do not have a representation yet assume
// representable for now. This can happen for recursive types like:
//
// public enum E {
// case foo([E?])
// }
//
// We make a decision about these types when the function that first
// encountered them returns.
if (!inserted)
return it->second ? (*it->second) : ClangRepresentation::representable;
CFunctionSignatureTypePrinterModifierDelegate delegate;
CFunctionSignatureTypePrinter typePrinter(
llvm::nulls(), llvm::nulls(), typeMapping, OutputLanguageMode::Cxx,
interopContext, delegate, emittedModule, declPrinter,
FunctionSignatureTypeUse::TypeReference);
return typePrinter.visit(ty, OptionalTypeKind::OTK_None,
/*isInOutParam=*/false);
auto result = typePrinter.visit(ty, OptionalTypeKind::OTK_None,
/*isInOutParam=*/false);
declPrinter.typeRepresentations[ty] = result;
return result;
}

void DeclAndTypeClangFunctionPrinter::printTypeName(
Expand Down
12 changes: 12 additions & 0 deletions test/Interop/SwiftToCxx/enums/recursive-enum.swift
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@@ -0,0 +1,12 @@
// RUN: %empty-directory(%t)
// RUN: %target-swift-frontend %s -module-name Enums -clang-header-expose-decls=all-public -typecheck -verify -emit-clang-header-path %t/enums.h
// RUN: %FileCheck %s < %t/enums.h

// RUN: %check-interop-cxx-header-in-clang(%t/enums.h -Wno-unused-private-field -Wno-unused-function -DSWIFT_CXX_INTEROP_HIDE_STL_OVERLAY)

public enum E {
case foo([E?])
}

// CHECK: class SWIFT_SYMBOL("s:5Enums1EO") E final {
// CHECK: SWIFT_INLINE_THUNK swift::Array<swift::Optional<E>> getFoo() const;