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[cxx-interop] Support reference types in function templates. #34536

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Merged
merged 1 commit into from
Nov 7, 2020
Merged

[cxx-interop] Support reference types in function templates. #34536

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16 changes: 14 additions & 2 deletions lib/ClangImporter/ImportType.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1814,8 +1814,20 @@ ParameterList *ClangImporter::Implementation::importFunctionParameterList(
// Import the parameter type into Swift.
Type swiftParamTy;
bool isParamTypeImplicitlyUnwrapped = false;
if (auto *templateParamType =
dyn_cast<clang::TemplateTypeParmType>(paramTy)) {

auto referenceType = dyn_cast<clang::ReferenceType>(paramTy);
if (referenceType &&
isa<clang::TemplateTypeParmType>(referenceType->getPointeeType())) {
auto pointeeType = referenceType->getPointeeType();
auto templateParamType = cast<clang::TemplateTypeParmType>(pointeeType);
PointerTypeKind pointerKind = pointeeType.getQualifiers().hasConst()
? PTK_UnsafePointer
: PTK_UnsafeMutablePointer;
auto genericType =
findGenericTypeInGenericDecls(templateParamType, genericParams);
swiftParamTy = genericType->wrapInPointer(pointerKind);
} else if (auto *templateParamType =
dyn_cast<clang::TemplateTypeParmType>(paramTy)) {
swiftParamTy =
findGenericTypeInGenericDecls(templateParamType, genericParams);
} else {
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6 changes: 6 additions & 0 deletions test/Interop/Cxx/templates/Inputs/function-templates.h
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Expand Up @@ -46,3 +46,9 @@ decltype(auto) testAuto(T arg) {
template <class T> struct Dep { using TT = T; };

template <class T> void useDependentType(typename Dep<T>::TT) {}

template <class T> void lvalueReference(T &ref) { ref = 42; }

template <class T> void constLvalueReference(const T &) {}

template <class T> void forwardingReference(T &&) {}
3 changes: 3 additions & 0 deletions test/Interop/Cxx/templates/function-template-module-interface.swift
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Expand Up @@ -6,3 +6,6 @@
// CHECK: func passThroughConst<T>(_ value: T) -> T
// CHECK: func returns_template<R, T, U>(_ a: T, _ b: U) -> R
// CHECK: func cannot_infer_template<T>()
// CHECK: func lvalueReference<T>(_ ref: UnsafeMutablePointer<T>)
// CHECK: func constLvalueReference<T>(_: UnsafePointer<T>)
// CHECK: func forwardingReference<T>(_: UnsafeMutablePointer<T>)
6 changes: 6 additions & 0 deletions test/Interop/Cxx/templates/function-template.swift
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Expand Up @@ -22,6 +22,12 @@ FunctionTemplateTestSuite.test("add<T, U> where T, U == Int") {
expectEqual(65, result)
}

FunctionTemplateTestSuite.test("lvalueReference<T> where T == Int") {
var value = 0
lvalueReference(&value)
expectEqual(value, 42)
}

// TODO: currently "Any" is imported as an Objective-C "id".
// This doesn't work without the Objective-C runtime.
#if _runtime(_ObjC)
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