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[cxx-interop] Diagnose Escapable C++ types with non-escapable fields #80671

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Merged
merged 1 commit into from
Apr 9, 2025
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[cxx-interop] Diagnose Escapable C++ types with non-escapable fields #80671

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4 changes: 4 additions & 0 deletions include/swift/AST/DiagnosticsClangImporter.def
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Original file line number Diff line number Diff line change
Expand Up @@ -377,5 +377,9 @@ NOTE(ptr_to_nonescapable,none,
"pointer to non-escapable type %0 cannot be imported",
(const clang::Type*))

NOTE(nonescapable_field_of_escapable, none,
"escapable record %0 cannot have non-escapable field '%1'",
(const clang::NamedDecl *, StringRef))

#define UNDEFINE_DIAGNOSTIC_MACROS
#include "DefineDiagnosticMacros.h"
18 changes: 17 additions & 1 deletion lib/ClangImporter/ImportDecl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2401,7 +2401,23 @@ namespace {
continue;
}

members.push_back(cast<VarDecl>(member));
auto *vd = cast<VarDecl>(member);
if (!isNonEscapable) {
if (const auto *fd = dyn_cast<clang::FieldDecl>(nd))
if (evaluateOrDefault(
Impl.SwiftContext.evaluator,
ClangTypeEscapability({fd->getType().getTypePtr(), &Impl}),
CxxEscapability::Unknown) ==
CxxEscapability::NonEscapable) {
Impl.addImportDiagnostic(
decl,
Diagnostic(diag::nonescapable_field_of_escapable, decl,
nd->getName()),
decl->getLocation());
return nullptr;
}
}
members.push_back(vd);
}

bool hasReferenceableFields = !members.empty();
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11 changes: 10 additions & 1 deletion test/Interop/Cxx/class/nonescapable-errors.swift
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Expand Up @@ -95,12 +95,21 @@ const View* usedToCrash(const View* p) {
return p;
}

struct SWIFT_ESCAPABLE Invalid {
View v;
};

//--- test.swift
import Test
import CxxStdlib

// CHECK: error: cannot find type 'Invalid' in scope
// CHECK: note: escapable record 'Invalid' cannot have non-escapable field 'v'
public func importInvalid(_ x: Invalid) {
}

// CHECK: error: a function with a ~Escapable result needs a parameter to depend on
// CHECK-NO-LIFETIMES: test.swift:6:32: error: a function with a ~Escapable result requires '-enable-experimental-feature LifetimeDependence'
// CHECK-NO-LIFETIMES: test.swift:11:32: error: a function with a ~Escapable result requires '-enable-experimental-feature LifetimeDependence'
public func noAnnotations() -> View {
// CHECK: nonescapable.h:16:7: warning: the returned type 'Owner' is annotated as escapable; it cannot have lifetime dependencies
// CHECK-NO-LIFETIMES: nonescapable.h:16:7: warning: the returned type 'Owner' is annotated as escapable; it cannot have lifetime dependencies
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