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[cxx-interop] Disable debug info in synthesized C++ methods #80094

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Merged
merged 1 commit into from
Mar 20, 2025
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[cxx-interop] Disable debug info in synthesized C++ methods #80094

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1 change: 1 addition & 0 deletions lib/ClangImporter/SwiftDeclSynthesizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2106,6 +2106,7 @@ clang::CXXMethodDecl *SwiftDeclSynthesizer::synthesizeCXXForwardingMethod(
newMethod->setImplicit();
newMethod->setImplicitlyInline();
newMethod->setAccess(clang::AccessSpecifier::AS_public);
newMethod->addAttr(clang::NoDebugAttr::CreateImplicit(clangCtx));
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@Xazax-hun Xazax-hun Mar 18, 2025

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I am a bit curious what is going on here. We are specifying the source range for the created method here, so I would suspect codegen to generate the right debug info based on that. Or is this due to missing source locations in the body of the function? Should we add this attribute to other synthesized functions as well?

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@egorzhdan egorzhdan Mar 18, 2025

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Should we add this attribute to other synthesized functions as well?

Yeah I think so, but let's make it a separate change to make this diff smaller and easier to cherry-pick.

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@susmonteiro susmonteiro Mar 19, 2025

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Or is this due to missing source locations in the body of the function?

Yes, exactly - particularly on calls to destructors in the body of the synthesized function. I've updated the PR description.

if (method->hasAttr<clang::CFReturnsRetainedAttr>()) {
// Return an FRT field at +1 if the base method also follows this
// convention.
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9 changes: 9 additions & 0 deletions test/Interop/Cxx/class/inheritance/Inputs/virtual-methods.h
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Expand Up @@ -50,6 +50,10 @@ struct DerivedFromCallsPureMethod : CallsPureMethod {

struct DerivedFromDerivedFromCallsPureMethod : DerivedFromCallsPureMethod {};

struct HasDestructor {
~HasDestructor() {}
};

// MARK: Reference Types:

#define IMMORTAL_FRT \
Expand All @@ -76,6 +80,11 @@ struct IMMORTAL_FRT DerivedFromImmortal : public Immortal {
static DerivedFromImmortal *_Nonnull create() { return new DerivedFromImmortal(); }
};

struct IMMORTAL_FRT Immortal2 {
public:
virtual void virtualMethod(HasDestructor) = 0;
};

inline const ImmortalBase *_Nonnull castToImmortalBase(
const Immortal *_Nonnull immortal) {
return static_cast<const ImmortalBase *>(immortal);
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11 changes: 11 additions & 0 deletions test/Interop/Cxx/class/inheritance/virtual-methods.swift
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@@ -1,6 +1,7 @@
// RUN: %target-run-simple-swift(-I %S/Inputs -cxx-interoperability-mode=swift-5.9)
// RUN: %target-run-simple-swift(-I %S/Inputs -cxx-interoperability-mode=swift-6)
// RUN: %target-run-simple-swift(-I %S/Inputs -cxx-interoperability-mode=upcoming-swift)
// RUN: %target-run-simple-swift(-g -I %S/Inputs -cxx-interoperability-mode=default)

// REQUIRES: executable_test

Expand Down Expand Up @@ -53,4 +54,14 @@ if #available(SwiftStdlib 5.8, *) {
}
}

#if !os(Windows)
// FIXME in Windows, non-trivial C++ class with trivial ABI is not yet available in Swift
VirtualMethodsTestSuite.test("C++ virtual method with complex parameter") {
@available(macOS 13.3, *)
func f(simpleClass: HasDestructor, immortalClass: Immortal2) {
immortalClass.virtualMethod(simpleClass)
}
}
#endif

runAllTests()