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[cxx-interop] Prevent crash when importing a std::optional of nonescapable #83973

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Sep 2, 2025
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[cxx-interop] Prevent crash when importing a std::optional of nonescapable #83973

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15 changes: 13 additions & 2 deletions lib/ClangImporter/ImportDecl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2413,8 +2413,18 @@ namespace {
}

auto *vd = cast<VarDecl>(member);
if (!isNonEscapable) {
if (const auto *fd = dyn_cast<clang::FieldDecl>(nd))
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Non-escapable is viral to the parents, so we should expect the parent record to be non-escapable when an indirect field is non-escapable. Would doing the same thing for both direct and indirect fields run into problems?

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That's a good point, thanks. We can do the same thing for indirect fields by assuming that an anonymous union/struct can never be escapable, and thus we can compare the escapability of these indirect fields directly with the outer record (i.e. skipping the comparison with the anonymous record)

auto getFieldDecl =
[](const clang::NamedDecl *decl) -> const clang::FieldDecl * {
if (const clang::FieldDecl *fd = dyn_cast<clang::FieldDecl>(decl))
return fd;
if (const clang::IndirectFieldDecl *ind =
dyn_cast<clang::IndirectFieldDecl>(decl))
return ind->getAnonField();
return nullptr;
};

if (!isNonEscapable && !decl->isAnonymousStructOrUnion()) {
if (const auto *fd = getFieldDecl(nd)) {
if (evaluateOrDefault(
Impl.SwiftContext.evaluator,
ClangTypeEscapability({fd->getType().getTypePtr(), &Impl}),
Expand All @@ -2427,6 +2437,7 @@ namespace {
decl->getLocation());
return nullptr;
}
}
}
members.push_back(vd);
}
Expand Down
113 changes: 86 additions & 27 deletions test/Interop/Cxx/class/nonescapable-errors.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ module Test {
//--- Inputs/nonescapable.h
#include "swift/bridging"
#include <vector>
#include <optional>

struct SWIFT_NONESCAPABLE View {
View() : member(nullptr) {}
Expand Down Expand Up @@ -115,64 +116,107 @@ struct SWIFT_ESCAPABLE Invalid {
View v;
};

struct SWIFT_NONESCAPABLE NonEscapable {};

template<typename T>
struct HasAnonUnion {
union {
int known;
T unknown;
};
};

template<typename T>
struct HasAnonStruct {
struct {
int known;
T unknown;
};
};

template<typename T>
struct SWIFT_NONESCAPABLE NonEscapableHasAnonUnion {
union {
int known;
T unknown;
};
};

using HasAnonUnionNonEscapable = HasAnonUnion<NonEscapable>;
using HasAnonStructNonEscapable = HasAnonStruct<NonEscapable>;
using NonEscapableHasAnonUnionNonEscapable = NonEscapableHasAnonUnion<NonEscapable>;
using NonEscapableOptional = std::optional<NonEscapable>;

//--- 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'
// CHECK-NO-LIFETIMES: error: cannot find type 'Invalid' in scope
// CHECK-NO-LIFETIMES: 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:11:32: error: a function cannot return a ~Escapable result
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@susmonteiro

You can make these line numbers resilient to this type of cascading change using:

// CHECK-NO-LIFETIMES: test.swift:[[@LINE+1]]:32: error: a function cannot return a ~Escapable result

By default this would be broken by split-files if you use FileCheck %s, since the line numbers change. This can be resolved by either using Filecheck %t/test.swift, or calling split-files --leading-lines which pads each file to preserve line numbers.

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Oh interesting, thanks!

// CHECK-NO-LIFETIMES: test.swift:13:32: error: a function cannot return a ~Escapable result
public func noAnnotations() -> View {
// CHECK: nonescapable.h:24:7: warning: the returned type 'Owner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:24:7: warning: the returned type 'Owner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK: nonescapable.h:25:7: warning: the returned type 'Owner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:25:7: warning: the returned type 'Owner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
f(nil)
// CHECK: nonescapable.h:28:7: warning: the returned type 'Owner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:28:7: warning: the returned type 'Owner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK: nonescapable.h:29:7: warning: the returned type 'Owner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:29:7: warning: the returned type 'Owner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// No duplicate warning for f2:
// CHECK-NOT: nonescapable.h:28
// CHECK-NOT: nonescapable.h:29
f2(nil, nil)
// CHECK: nonescapable.h:32:19: warning: the returned type 'TemplatedIntOwner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:32:19: warning: the returned type 'TemplatedIntOwner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK: nonescapable.h:33:19: warning: the returned type 'TemplatedIntOwner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:33:19: warning: the returned type 'TemplatedIntOwner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// No duplicate warning for f3:
// CHECK-NOT: nonescapable.h:32
// CHECK-NOT: nonescapable.h:33
f3(nil)
// CHECK: nonescapable.h:36:21: warning: the returned type 'TemplatedFloatOwner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:36:21: warning: the returned type 'TemplatedFloatOwner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK: nonescapable.h:37:21: warning: the returned type 'TemplatedFloatOwner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:37:21: warning: the returned type 'TemplatedFloatOwner' is annotated as escapable; it cannot have lifetime dependencies [#ClangDeclarationImport]
// No duplicate warning for f4:
// CHECK-NOT: nonescapable.h:34
// CHECK-NOT: nonescapable.h:35
f4(nil)
// CHECK: nonescapable.h:40:6: warning: the returned type 'View' is annotated as non-escapable; its lifetime dependencies must be annotated [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:40:6: warning: the returned type 'View' is annotated as non-escapable; its lifetime dependencies must be annotated [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:40:6: error: a function cannot return a ~Escapable result
// CHECK: nonescapable.h:41:6: warning: the returned type 'View' is annotated as non-escapable; its lifetime dependencies must be annotated [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:41:6: warning: the returned type 'View' is annotated as non-escapable; its lifetime dependencies must be annotated [#ClangDeclarationImport]
// CHECK-NO-LIFETIMES: nonescapable.h:41:6: error: a function cannot return a ~Escapable result
g(nil)
h1(nil)
// CHECK-NO-LIFETIMES: nonescapable.h:50:21: error: a function cannot return a ~Escapable result
h2(nil)
// CHECK-NO-LIFETIMES: nonescapable.h:51:21: error: a function cannot return a ~Escapable result
h2(nil)
// CHECK-NO-LIFETIMES: nonescapable.h:52:21: error: a function cannot return a ~Escapable result
h3(nil)
i1()
// CHECK: nonescapable.h:55:39: error: template parameter 'Missing' does not exist
// CHECK-NO-LIFETIMES: nonescapable.h:55:39: error: template parameter 'Missing' does not exist
// CHECK: nonescapable.h:56:39: error: template parameter 'Missing' does not exist
// CHECK-NO-LIFETIMES: nonescapable.h:56:39: error: template parameter 'Missing' does not exist
i2()
// CHECK: nonescapable.h:61:33: error: template parameter 'S' expected to be a type parameter
// CHECK-NO-LIFETIMES: nonescapable.h:61:33: error: template parameter 'S' expected to be a type parameter
// CHECK: nonescapable.h:62:33: error: template parameter 'S' expected to be a type parameter
// CHECK: nonescapable.h:80:41: error: a function with a ~Escapable result needs a parameter to depend on
// CHECK: note: '@_lifetime(immortal)' can be used to indicate that values produced
// CHECK-NO-LIFETIMES: nonescapable.h:62:33: error: template parameter 'S' expected to be a type parameter
j1()
// CHECK-NO-LIFETIMES: nonescapable.h:79:41: error: a function cannot return a ~Escapable result
j2()
// CHECK-NO-LIFETIMES: nonescapable.h:80:41: error: a function cannot return a ~Escapable result
j2()
// CHECK: nonescapable.h:81:41: error: a function with a ~Escapable result needs a parameter to depend on
// CHECK-NO-LIFETIMES: nonescapable.h:81:41: error: a function cannot return a ~Escapable result
// CHECK: note: '@_lifetime(immortal)' can be used to indicate that values produced
j3()
k1();
// CHECK-NO-LIFETIMES: nonescapable.h:86:15: error: a function cannot return a ~Escapable result
// CHECK: nonescapable.h:87:15: error: a function with a ~Escapable result needs a parameter to depend on
// CHECK: nonescapable.h:87:15: note: '@_lifetime(immortal)' can be used to indicate that values produced
// CHECK-NO-LIFETIMES: nonescapable.h:87:15: error: a function cannot return a ~Escapable result

k2();
// CHECK-NO-LIFETIMES: nonescapable.h:87:22: error: a function cannot return a ~Escapable result
// CHECK: nonescapable.h:88:22: error: a function with a ~Escapable result needs a parameter to depend on
// CHECK-NO-LIFETIMES: nonescapable.h:88:22: error: a function cannot return a ~Escapable result
// CHECK: note: '@_lifetime(immortal)' can be used to indicate that values produced
k3();
l1();
// CHECK: nonescapable.h:93:12: error: a function with a ~Escapable result needs a parameter to depend on
// CHECK-NO-LIFETIMES: nonescapable.h:93:12: error: a function cannot return a ~Escapable result
// CHECK: nonescapable.h:94:12: error: a function with a ~Escapable result needs a parameter to depend on
// CHECK: nonescapable.h:94:12: note: '@_lifetime(immortal)' can be used to indicate that values produced by this initializer have no lifetime dependencies
// CHECK-NO-LIFETIMES: nonescapable.h:94:12: error: a function cannot return a ~Escapable result
l2();
return View()
}
Expand All @@ -188,6 +232,21 @@ public func test3(_ x: inout View) {
// CHECK-NO-LIFETIMES: note: return type unavailable (cannot import)
// CHECK-NO-LIFETIMES: pointer to non-escapable type 'View' cannot be imported
}

public func anonymousUnions() {
_ = HasAnonUnionNonEscapable()
// CHECK: error: cannot find 'HasAnonUnionNonEscapable' in scope
// CHECK-NO-LIFETIMES: error: cannot find 'HasAnonUnionNonEscapable' in scope
_ = HasAnonStructNonEscapable()
// CHECK: error: cannot find 'HasAnonStructNonEscapable' in scope
// CHECK-NO-LIFETIMES: error: cannot find 'HasAnonStructNonEscapable' in scope
_ = NonEscapableHasAnonUnionNonEscapable()
_ = NonEscapableOptional()
// CHECK: error: cannot infer the lifetime dependence scope on an initializer with a ~Escapable parameter, specify '@_lifetime(borrow {{.*}})' or '@_lifetime(copy {{.*}})'
// CHECK-NO-LIFETIMES: error: an initializer cannot return a ~Escapable result
// CHECK-NO-LIFETIMES: error: an initializer cannot return a ~Escapable result
}

// CHECK-NOT: error
// CHECK-NOT: warning
// CHECK-NO-LIFETIMES-NOT: error
Expand Down