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[cxx-interop] Do not import C++23 deducing this #84537

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Merged
merged 1 commit into from
Sep 26, 2025
Merged

[cxx-interop] Do not import C++23 deducing this #84537

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4 changes: 4 additions & 0 deletions lib/ClangImporter/ImportName.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1538,6 +1538,10 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
if (!swift3OrLaterName && isa<clang::CXXMethodDecl>(D)) {
return ImportedName();
}
// If this function uses C++23 deducing this, bail.
if (auto functionDecl = dyn_cast<clang::FunctionDecl>(D))
if (functionDecl->hasCXXExplicitFunctionObjectParameter())
return {};

// Dig out the definition, if there is one.
if (auto def = getDefinitionForClangTypeDecl(D)) {
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4 changes: 4 additions & 0 deletions test/Interop/Cxx/class/method/Inputs/deducing-this.h
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@@ -0,0 +1,4 @@
struct HasDeducingThis {
int value;
int deducingRef(this HasDeducingThis &self) { return self.value; }
};
5 changes: 5 additions & 0 deletions test/Interop/Cxx/class/method/Inputs/module.modulemap
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@@ -1,3 +1,8 @@
module DeducingThis {
header "deducing-this.h"
requires cplusplus23
}

module Methods {
header "methods.h"
requires cplusplus
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6 changes: 6 additions & 0 deletions test/Interop/Cxx/class/method/deducing-this-module-interface.swift
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@@ -0,0 +1,6 @@
// RUN: %target-swift-ide-test -print-module -module-to-print=DeducingThis -I %S/Inputs -source-filename=x -cxx-interoperability-mode=upcoming-swift -Xcc -std=c++23 | %FileCheck %s

// This mostly ensures that we don't import deducing this method with an incorrect signature.

// CHECK: struct HasDeducingThis {
// CHECK-NOT: deducingRef