Merge #1268

1268: Fix Slice Type Layout r=philberty a=philberty

Slices in Rust are represented by TypePaths such as '[i32]'. Though if you
actually try to use this explicit type-path you will hit errors such as
this type has an unknown size at compile time. This is because this is
actually what Rust calls a dynamically sized type. This means when you use
types such as: '&[i32]' it is not actually a reference type to a slice. Its
a slice in its entirety this means for lack of a better word when you use
'*const [i32]' or '&mut [i32]' we end up actually passing around a struct
by value _not_ at pointer/reference to it.

This patch changes the type-layout so that we handle this layout change
properly. This patch will also need to be applied to str types which I
believe have a similar layout for safety.

The patch also sets up TYPE_MAIN_VARIANT so that we can avoid unnessecary
view_convert_expressions between *const [i32] and &mut [i32] which will
have the same layout.

Reference:

https://doc.rust-lang.org/reference/dynamically-sized-types.html

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=672adac002939a2dab43b8d231adc1dc

Fixes #1232


Co-authored-by: Philip Herron <philip.herron@embecosm.com>

0 files changed, 0 insertions, 0 deletions