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[cxx-interop] Make borrowing specifiers more precise #78946

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Merged
merged 1 commit into from
Jan 29, 2025
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[cxx-interop] Make borrowing specifiers more precise #78946

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10 changes: 7 additions & 3 deletions lib/ClangImporter/ImportType.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2687,14 +2687,18 @@ static ParamDecl *getParameterInfo(ClangImporter::Implementation *impl,
}
}

// Parameters of type const T& imported as T, make sure we borrow from them
// when they have lifetime annotations.
bool isBorrowing = (param->getAttr<clang::LifetimeBoundAttr>() ||
param->getAttr<clang::LifetimeCaptureByAttr>()) &&
param->getType()->isReferenceType();
// Foreign references are already references so they don't need to be passed
// as inout.
paramInfo->setSpecifier(
isConsuming ? ParamSpecifier::Consuming
: (isInOut ? ParamSpecifier::InOut
: (param->getAttr<clang::LifetimeBoundAttr>()
? ParamSpecifier::Borrowing
: ParamSpecifier::Default)));
: (isBorrowing ? ParamSpecifier::Borrowing
: ParamSpecifier::Default)));
paramInfo->setInterfaceType(swiftParamTy);
impl->recordImplicitUnwrapForDecl(paramInfo, isParamTypeImplicitlyUnwrapped);

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4 changes: 2 additions & 2 deletions test/Interop/Cxx/class/nonescapable-lifetimebound.swift
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Expand Up @@ -111,9 +111,9 @@ CaptureView getCaptureView(const Owner& owner [[clang::lifetimebound]]) {
// CHECK: sil [clang getViewFromEither] {{.*}} : $@convention(c) (@in_guaranteed Owner, @in_guaranteed Owner) -> @lifetime(borrow 0, borrow 1) @owned View
// CHECK: sil [clang Owner.handOutView] {{.*}} : $@convention(cxx_method) (@in_guaranteed Owner) -> @lifetime(borrow 0) @owned View
// CHECK: sil [clang Owner.handOutView2] {{.*}} : $@convention(cxx_method) (View, @in_guaranteed Owner) -> @lifetime(borrow 1) @owned View
// CHECK: sil [clang getViewFromEither] {{.*}} : $@convention(c) (@guaranteed View, @guaranteed View) -> @lifetime(copy 0, copy 1) @owned View
// CHECK: sil [clang getViewFromEither] {{.*}} : $@convention(c) (View, View) -> @lifetime(copy 0, copy 1) @owned View
// CHECK: sil [clang View.init] {{.*}} : $@convention(c) () -> @lifetime(immortal) @out View
// CHECK: sil [clang OtherView.init] {{.*}} : $@convention(c) (@guaranteed View) -> @lifetime(copy 0) @out OtherView
// CHECK: sil [clang OtherView.init] {{.*}} : $@convention(c) (View) -> @lifetime(copy 0) @out OtherView
// CHECK: sil [clang returnsImmortal] {{.*}} : $@convention(c) () -> @lifetime(immortal) @owned View
// CHECK: sil [clang copyView] {{.*}} : $@convention(c) (View, @lifetime(copy 0) @inout View) -> ()
// CHECK: sil [clang getCaptureView] {{.*}} : $@convention(c) (@in_guaranteed Owner) -> @lifetime(borrow 0) @owned CaptureView
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7 changes: 7 additions & 0 deletions test/Interop/Cxx/stdlib/Inputs/std-span.h
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Expand Up @@ -62,6 +62,13 @@ struct DependsOnSelf {

inline struct SpanBox getStructSpanBox() { return {iarray, iarray, sarray, sarray}; }

struct CaptureByReference {
void set(const std::vector<int>& x [[clang::lifetime_capture_by(this)]]) {
this->x = ConstSpanOfInt(x.data(), x.size());
};
ConstSpanOfInt x;
};

inline void funcWithSafeWrapper(ConstSpanOfInt s [[clang::noescape]]) {}

inline ConstSpanOfInt funcWithSafeWrapper2(ConstSpanOfInt s
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5 changes: 3 additions & 2 deletions test/Interop/Cxx/stdlib/std-span-interface.swift
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Expand Up @@ -19,8 +19,9 @@ import CxxStdlib
// CHECK-NEXT: @_alwaysEmitIntoClient public mutating func get() -> Span<CInt>
// CHECK-NEXT: mutating func get() -> ConstSpanOfInt

// CHECK: mutating func set(_ x: borrowing std.{{.*}}vector<CInt, std.{{.*}}allocator<CInt>>)
// CHECK: func funcWithSafeWrapper(_ s: ConstSpanOfInt)
// CHECK-NEXT: func funcWithSafeWrapper2(_ s: borrowing ConstSpanOfInt) -> ConstSpanOfInt
// CHECK-NEXT: func funcWithSafeWrapper2(_ s: ConstSpanOfInt) -> ConstSpanOfInt
// CHECK-NEXT: func funcWithSafeWrapper3(_ v: borrowing VecOfInt) -> ConstSpanOfInt
// CHECK: struct X {
// CHECK-NEXT: init()
Expand All @@ -29,6 +30,6 @@ import CxxStdlib
// CHECK-NEXT: }
// CHECK-NEXT: @_alwaysEmitIntoClient public func funcWithSafeWrapper(_ s: Span<CInt>)
// CHECK-NEXT: @lifetime(s)
// CHECK-NEXT: @_alwaysEmitIntoClient public func funcWithSafeWrapper2(_ s: borrowing Span<CInt>) -> Span<CInt>
// CHECK-NEXT: @_alwaysEmitIntoClient public func funcWithSafeWrapper2(_ s: Span<CInt>) -> Span<CInt>
// CHECK-NEXT: @lifetime(borrow v)
// CHECK-NEXT: @_alwaysEmitIntoClient public func funcWithSafeWrapper3(_ v: borrowing VecOfInt) -> Span<CInt>