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Support [[lifetimebound]] parameters in constructors. #414

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Merged
copybara-service merged 1 commit into from
Feb 6, 2026
+196 −8
Merged

Support [[lifetimebound]] parameters in constructors. #414

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24 changes: 16 additions & 8 deletions rs_bindings_from_cc/generate_bindings/lifetime_defaults_transform.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -282,11 +282,12 @@ impl LifetimeDefaults {
// TODO(b/475407556): Support lifetime_capture_by.
let mut return_lifetime: Vec<Rc<str>> = func.return_type.explicit_lifetimes.clone();
let mut has_lifetimebound = false;
let is_constructor = func.cc_name == ir::UnqualifiedIdentifier::Constructor;
// First, check to see if there are any existing lifetime annotations that we need to
// respect.
for param in func.params.iter() {
if param.clang_lifetimebound {
has_lifetimebound = true;
for (ix, param) in func.params.iter().enumerate() {
if param.clang_lifetimebound || (is_constructor && ix == 0) {
has_lifetimebound |= param.clang_lifetimebound;
if return_lifetime.is_empty() {
// If a [[lifetimebound]] parameter already has a lifetime annotation and we
// don't have a lifetime for the return value yet, use the parameter's
Expand Down Expand Up @@ -316,17 +317,24 @@ impl LifetimeDefaults {
// annotations, we need to create new lifetime variables for the return value.
// Use a reserved name for these so we don't conflict with lifetimes embedded in
// types or on non-[[lifetimebound]] parameters.
let arity = self.get_lifetime_arity(&func.return_type)?;
let arity = self.get_lifetime_arity(if is_constructor {
&func.params[0].type_
} else {
&func.return_type
})?;
for _ in 0..arity {
return_lifetime.push(self.bindings.fresh_name_for(&Rc::from("__rv")))
let name = if is_constructor { &Rc::from("__this") } else { &Rc::from("__rv") };
return_lifetime.push(self.bindings.fresh_name_for(name))
}
}
for param in func.params.iter_mut() {
if param.clang_lifetimebound {
for (ix, param) in func.params.iter_mut().enumerate() {
if param.clang_lifetimebound || (is_constructor && ix == 0) {
param.type_.explicit_lifetimes = return_lifetime.clone();
}
}
func.return_type.explicit_lifetimes = return_lifetime;
if !is_constructor {
func.return_type.explicit_lifetimes = return_lifetime;
}
Ok(())
}

Expand Down
180 changes: 180 additions & 0 deletions rs_bindings_from_cc/generate_bindings/lifetime_defaults_transform_test.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -590,6 +590,186 @@ fn test_this_lifetime_returned_for_member_function_with_reference_param() -> Res
Ok(())
}

#[gtest]
fn test_this_lifetime_applied_for_constructor() -> Result<()> {
let ir = ir_from_assumed_lifetimes_cc(
&(with_full_lifetime_macros()
+ r#"
struct S { S(); S(const S& o) = delete; S(const S&& o) = delete; };
"#),
)?;
let dir = lifetime_defaults_transform(&ir)?;
assert_ir_matches!(
dir,
quote! {
Func {
cc_name: Constructor,
rs_name: Constructor, ...
return_type: CcType { ... variant: Primitive(Void) ... }, ...
params: [
FuncParam {
type_: CcType { ... explicit_lifetimes: ["__this"] ... },
identifier: "__this", ...
}
],
lifetime_params: [],
...
lifetime_inputs: ["__this"],
...
}
}
);
Ok(())
}

#[gtest]
fn test_this_lifetime_annotation_applied_for_constructor() -> Result<()> {
let ir = ir_from_assumed_lifetimes_cc(
&(with_full_lifetime_macros()
+ r#"
struct S { S() $a; S(const S& o) = delete; S(const S&& o) = delete; };
"#),
)?;
let dir = lifetime_defaults_transform(&ir)?;
assert_ir_matches!(
dir,
quote! {
Func {
cc_name: Constructor,
rs_name: Constructor, ...
return_type: CcType { ... variant: Primitive(Void) ... }, ...
params: [
FuncParam {
type_: CcType { ... explicit_lifetimes: ["a"] ... },
identifier: "__this", ...
}
],
lifetime_params: [],
...
lifetime_inputs: ["a"],
...
}
}
);
Ok(())
}

#[gtest]
fn test_param_lifetime_inferred_for_constructor() -> Result<()> {
let ir = ir_from_assumed_lifetimes_cc(
&(with_full_lifetime_macros()
+ r#"
struct S { S(int& i1); S(const S& o) = delete; S(const S&& o) = delete; };
"#),
)?;
let dir = lifetime_defaults_transform(&ir)?;
assert_ir_matches!(
dir,
quote! {
Func {
cc_name: Constructor,
rs_name: Constructor, ...
return_type: CcType { ... variant: Primitive(Void) ... }, ...
params: [
FuncParam {
type_: CcType { ... explicit_lifetimes: ["__this"] ... },
identifier: "__this", ...
},
FuncParam {
type_: CcType { ... explicit_lifetimes: ["i1"] ... },
identifier: "i1", ...
},
],
lifetime_params: [],
...
lifetime_inputs: ["__this", "i1"],
...
}
}
);
Ok(())
}

#[gtest]
fn test_param_lifetimebound_to_this_in_constructor() -> Result<()> {
let ir = ir_from_assumed_lifetimes_cc(
&(with_full_lifetime_macros()
+ r#"
struct S {
S(int& i1 [[clang::lifetimebound]]);
S(const S& o) = delete;
S(const S&& o) = delete;
};
"#),
)?;
let dir = lifetime_defaults_transform(&ir)?;
assert_ir_matches!(
dir,
quote! {
Func {
cc_name: Constructor,
rs_name: Constructor, ...
return_type: CcType { ... variant: Primitive(Void) ... }, ...
params: [
FuncParam {
type_: CcType { ... explicit_lifetimes: ["__this"] ... },
identifier: "__this", ...
},
FuncParam {
type_: CcType { ... explicit_lifetimes: ["__this"] ... },
identifier: "i1", ...
},
],
lifetime_params: [],
...
lifetime_inputs: ["__this"],
...
}
}
);
Ok(())
}

#[gtest]
fn test_param_lifetimebound_to_this_in_constructor_explicit_lifetime() -> Result<()> {
let ir = ir_from_assumed_lifetimes_cc(
&(with_full_lifetime_macros()
+ r#"
struct S {
S(int& i1 [[clang::lifetimebound]]) $a;
S(const S& o) = delete;
S(const S&& o) = delete;
};
"#),
)?;
let dir = lifetime_defaults_transform(&ir)?;
assert_ir_matches!(
dir,
quote! {
Func {
cc_name: Constructor,
rs_name: Constructor, ...
return_type: CcType { ... variant: Primitive(Void) ... }, ...
params: [
FuncParam {
type_: CcType { ... explicit_lifetimes: ["a"] ... },
identifier: "__this", ...
},
FuncParam {
type_: CcType { ... explicit_lifetimes: ["a"] ... },
identifier: "i1", ...
},
],
lifetime_params: [],
...
lifetime_inputs: ["a"],
...
}
}
);
Ok(())
}

#[gtest]
fn test_binding_context_has_static() -> Result<()> {
let mut ctx = BindingContext::new();
Expand Down