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madsmtmmadsmtm
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Add encoding UI test for function pointers
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8 files changed

+131
-3
lines changed

8 files changed

+131
-3
lines changed

‎objc2-encode/src/encode.rs

Lines changed: 1 addition & 2 deletions
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@@ -430,8 +430,7 @@ encode_pointer_impls!(
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///
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/// Ideally we'd implement it for all function pointers, but due to coherence
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/// issues, see <https://github.com/rust-lang/rust/issues/56105>, function
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/// pointers that take arguments with "special lifetimes" (don't know the
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/// termonology) don't get implemented properly.
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/// pointers that are higher-ranked over lifetimes don't get implemented.
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///
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/// We could fix it by adding those impls and allowing `coherence_leak_check`,
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/// but it would have to be done for _all_ references, `Option<&T>` and such as

‎objc2-foundation/src/array.rs

Lines changed: 4 additions & 1 deletion
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@@ -303,7 +303,10 @@ impl<T: Message, O: Ownership> NSMutableArray<T, O> {
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NSComparisonResult::from((*closure)(obj1, obj2))
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}
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let f: extern "C" fn(_, _, _) -> _ = compare_with_closure::<T, F>;
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// We can't name the actual lifetimes in use here, so use `_`.
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// See also https://github.com/rust-lang/rust/issues/56105
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let f: extern "C" fn(_, _, *mut c_void) -> NSComparisonResult =
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compare_with_closure::<T, F>;
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// Grab a type-erased pointer to the closure (a pointer to stack).
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let mut closure = compare;

‎tests/ui/fn_ptr_reference_encode.rs

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@@ -0,0 +1,22 @@
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//! Test that `Encode` is not implemented for function pointers that are
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//! higher-ranked over lifetimes.
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//!
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//! Ideally, they should be, but they can't be right now.
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//!
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//! (Also test that we can use `_` to work around this).
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use objc2::Encode;
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extern "C" fn my_fn(_x: &i32) {}
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fn e<T: Encode>(_x: T) {}
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fn main() {
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// Works
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e(my_fn as extern "C" fn(_));
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// Can't be written:
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// let encoding = <extern "C" fn(_) as Encode>::ENCODING;
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// Fails
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e(my_fn as extern "C" fn(&i32));
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let encoding = <extern "C" fn(&i32) as Encode>::ENCODING;
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}

‎tests/ui/fn_ptr_reference_encode.stderr

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@@ -0,0 +1,8 @@
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error: implementation of `Encode` is not general enough
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--> ui/fn_ptr_reference_encode.rs:20:5
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|
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20 | e(my_fn as extern "C" fn(&i32));
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| ^ implementation of `Encode` is not general enough
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|
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= note: `Encode` would have to be implemented for the type `for<'r> extern "C" fn(&'r i32)`
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= note: ...but `Encode` is actually implemented for the type `extern "C" fn(&'0 i32)`, for some specific lifetime `'0`

‎tests/ui/fn_ptr_reference_method.rs

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@@ -0,0 +1,27 @@
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//! Test how `MethodImplementation` is implemented regarding lifetimes in
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//! function pointers and whether they're higher-ranked over them.
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//!
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//! Ideally it should work for all of these, but it can't be right now.
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//!
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//! (`_` can be used to work around this, by letting the compiler choose an
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//! appropriate lifetime '0 that the trait is implemented for).
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use objc2::{class, sel};
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use objc2::declare::ClassBuilder;
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use objc2::runtime::{Object, Sel};
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extern "C" fn my_fn(_this: &Object, _cmd: Sel, _x: &Object) {}
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fn main() {
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let builder = ClassBuilder::new("SomeTestClass", class!(NSObject)).unwrap();
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unsafe {
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// Works
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builder.add_method(sel!(first:), my_fn as extern "C" fn(&Object, _, _));
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// Fails
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builder.add_method(sel!(none:), my_fn as extern "C" fn(_, _, _));
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builder.add_method(sel!(third:), my_fn as extern "C" fn(_, _, &Object));
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// Also fails, properly tested in `fn_ptr_reference_method2`
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builder.add_method(sel!(both:), my_fn as extern "C" fn(&Object, _, &Object));
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}
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}

‎tests/ui/fn_ptr_reference_method.stderr

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@@ -0,0 +1,47 @@
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error[E0277]: the trait bound `extern "C" fn(_, _, _): MethodImplementation` is not satisfied
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--> ui/fn_ptr_reference_method.rs:21:41
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|
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21 | builder.add_method(sel!(none:), my_fn as extern "C" fn(_, _, _));
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| ---------- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `MethodImplementation` is not implemented for `extern "C" fn(_, _, _)`
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| |
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| required by a bound introduced by this call
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|
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= help: the following other types implement trait `MethodImplementation`:
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B, C) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B, C, D) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B, C, D, E) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B, C, D, E, F) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B, C, D, E, F, G) -> R
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and 70 others
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note: required by a bound in `ClassBuilder::add_method`
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--> $WORKSPACE/objc2/src/declare.rs
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|
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| F: MethodImplementation<Callee = T>,
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `ClassBuilder::add_method`
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error[E0277]: the trait bound `for<'r> extern "C" fn(_, _, &'r objc2::runtime::Object): MethodImplementation` is not satisfied
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--> ui/fn_ptr_reference_method.rs:22:42
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|
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22 | builder.add_method(sel!(third:), my_fn as extern "C" fn(_, _, &Object));
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| ---------- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `MethodImplementation` is not implemented for `for<'r> extern "C" fn(_, _, &'r objc2::runtime::Object)`
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| |
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| required by a bound introduced by this call
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|
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= help: the following other types implement trait `MethodImplementation`:
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B, C) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B, C, D) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B, C, D, E) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B, C, D, E, F) -> R
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for<'r> extern "C" fn(&'r T, objc2::runtime::Sel, A, B, C, D, E, F, G) -> R
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and 70 others
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note: required by a bound in `ClassBuilder::add_method`
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--> $WORKSPACE/objc2/src/declare.rs
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|
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| F: MethodImplementation<Callee = T>,
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `ClassBuilder::add_method`

‎tests/ui/fn_ptr_reference_method2.rs

Lines changed: 14 additions & 0 deletions
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@@ -0,0 +1,14 @@
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//! Extra test for `fn_ptr_reference_method`
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//! (They fail at different compilation passes).
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use objc2::{class, sel};
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use objc2::declare::ClassBuilder;
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use objc2::runtime::{Object, Sel};
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extern "C" fn my_fn(_this: &Object, _cmd: Sel, _x: &Object) {}
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fn main() {
10+
let builder = ClassBuilder::new("SomeTestClass", class!(NSObject)).unwrap();
11+
unsafe {
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builder.add_method(sel!(both:), my_fn as extern "C" fn(&Object, Sel, &Object));
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}
14+
}

‎tests/ui/fn_ptr_reference_method2.stderr

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@@ -0,0 +1,8 @@
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error: implementation of `MethodImplementation` is not general enough
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--> ui/fn_ptr_reference_method2.rs:12:17
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|
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12 | builder.add_method(sel!(both:), my_fn as extern "C" fn(&Object, Sel, &Object));
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| ^^^^^^^^^^ implementation of `MethodImplementation` is not general enough
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|
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= note: `MethodImplementation` would have to be implemented for the type `for<'r, 's> extern "C" fn(&'r objc2::runtime::Object, objc2::runtime::Sel, &'s objc2::runtime::Object)`
8+
= note: ...but `MethodImplementation` is actually implemented for the type `for<'r> extern "C" fn(&'r objc2::runtime::Object, objc2::runtime::Sel, &'0 objc2::runtime::Object)`, for some specific lifetime `'0`

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