[gcc/devel/rust/master] Merge #1045

[gcc/devel/rust/master] Merge #1045

[Thomas Schwinge]

https://gcc.gnu.org/g:e8b9587d3a0615f497cfe9c66995c1f21e42a536

commit e8b9587d3a0615f497cfe9c66995c1f21e42a536
Merge: 729bbacbd17 afa451b311d
Author: bors[bot] <26634292+bors[bot]@users.noreply.github.com>
Date:   Mon Mar 28 14:22:24 2022 +0000

    Merge #1045
    
    1045: Add initial support for unsized method resolution r=philberty a=philberty
    
    In order to support slices, we end up with an operator overload call of:
    
    ```
    impl<T, I> Index<I> for [T]
    where
        I: SliceIndex<[T]>,
    {
        type Output = I::Output;
    
        fn index(&self, index: I) -> &I::Output {
            index.index(self)
        }
    }
    ```
    
    So this means the self, in this case, is an array[T,capacity] and the index parameter is of type Range<usize>. In order to actually call this method
    which has a self parameter of [T] we need to be able to 'unsize' the array
    into a slice.
    
    Addresses #849
    
    
    Co-authored-by: Philip Herron <philip.herron@embecosm.com>

Diff:

 gcc/rust/backend/rust-compile-base.h        |  3 +++
 gcc/rust/backend/rust-compile-expr.cc       | 30 +++++++++++++++++++++++++++++
 gcc/rust/typecheck/rust-autoderef.cc        | 21 ++++++++++++++++++++
 gcc/rust/typecheck/rust-autoderef.h         |  5 +++++
 gcc/rust/typecheck/rust-hir-dot-operator.cc | 15 +++++++++++++++
 gcc/rust/typecheck/rust-hir-type-check.h    |  1 +
 gcc/rust/typecheck/rust-tyctx.cc            |  7 +++++++
 7 files changed, 82 insertions(+)