[PATCH 6/8] rust: pin-init: remove `E` from `InitClosure`

[Gary Guo <gary@garyguo.net>]

Move `E` from type to trait impl block. This greatly shortens the
monomorphized type names. The `__pinned_init` function name is only
slightly shortened as it still encodes the `E` as part of `PinInit<T, E>`
in the symbol.

`T` cannot be moved to trait impl block otherwise it will start to conflict
with the `impl Init<T> for T` as Rust cannot deduce that there're no types
that fulfill `T: FnOnce(*mut T)`.

Signed-off-by: Gary Guo <gary@garyguo.net>
---
 rust/pin-init/src/lib.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/rust/pin-init/src/lib.rs b/rust/pin-init/src/lib.rs
index 9732af32795c..fd40c8f244a1 100644
--- a/rust/pin-init/src/lib.rs
+++ b/rust/pin-init/src/lib.rs
@@ -1096,11 +1096,11 @@ unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
 ///
 /// It is unsafe to create this type, since the closure needs to fulfill the same safety
 /// requirement as the `__pinned_init`/`__init` functions.
-struct InitClosure<F, T: ?Sized, E>(F, __internal::PhantomInvariant<(E, T)>);
+struct InitClosure<F, T: ?Sized>(F, __internal::PhantomInvariant<T>);
 
 // SAFETY: While constructing the `InitClosure`, the user promised that it upholds the
 // `__init` invariants.
-unsafe impl<T: ?Sized, F, E> Init<T, E> for InitClosure<F, T, E>
+unsafe impl<T: ?Sized, F, E> Init<T, E> for InitClosure<F, T>
 where
     F: FnOnce(*mut T) -> Result<(), E>,
 {
@@ -1112,7 +1112,7 @@ unsafe fn __init(self, slot: *mut T) -> Result<(), E> {
 
 // SAFETY: While constructing the `InitClosure`, the user promised that it upholds the
 // `__pinned_init` invariants.
-unsafe impl<T: ?Sized, F, E> PinInit<T, E> for InitClosure<F, T, E>
+unsafe impl<T: ?Sized, F, E> PinInit<T, E> for InitClosure<F, T>
 where
     F: FnOnce(*mut T) -> Result<(), E>,
 {

-- 
2.54.0