Rust makes all slice access an intrinsic

see: https://users.rust-lang.org/t/why-this-does-not-lead-to-recursion/50306/3

I tried this code:

unsafe impl<T> SliceIndex<[T]> for usize {
    type Output = T;

    fn get(self, slice: &[T]) -> Option<&T> {
        unsafe { Option::Some(&*self.get_unchecked(slice)) }
    }

    unsafe fn get_unchecked(self, slice: *const [T]) -> *const T {
        // SAFETY: the caller guarantees that `slice` is not dangling, so it
        // cannot be longer than `isize::MAX`. They also guarantee that
        // `self` is in bounds of `slice` so `self` cannot overflow an `isize`,
        // so the call to `add` is safe.
        unsafe { slice.as_ptr().add(self) }
    }

    fn index(self, slice: &[T]) -> &T {    
        // It works if you change this to unsafe { &*self.get_unchecked(slice) }
        // N.B., use intrinsic indexing
        &(*slice)[self]        
    }
}

I expected to see this happen: explanation

Instead, this happened:

test.rs: In function ‘<T as test::Index>::index<i32, usize>’:
test.rs:140:9: internal compiler error: in expand_expr_real_1, at expr.cc:10583
  140 |         index.index(self)
      |         ^
0x1605b99 expand_expr_real_1(tree_node*, rtx_def*, machine_mode, expand_modifier, rtx_def**, bool)
        ../../gccrs/gcc/expr.cc:10583
0x15fd3e3 expand_expr_real(tree_node*, rtx_def*, machine_mode, expand_modifier, rtx_def**, bool)
        ../../gccrs/gcc/expr.cc:8736
0x140544f expand_normal
        ../../gccrs/gcc/expr.h:307
0x14079d0 precompute_register_parameters
        ../../gccrs/gcc/calls.cc:985
0x140f854 expand_call(tree_node*, rtx_def*, int)
        ../../gccrs/gcc/calls.cc:3375
0x160ab60 expand_expr_real_1(tree_node*, rtx_def*, machine_mode, expand_modifier, rtx_def**, bool)
        ../../gccrs/gcc/expr.cc:11537
0x15fd3e3 expand_expr_real(tree_node*, rtx_def*, machine_mode, expand_modifier, rtx_def**, bool)
        ../../gccrs/gcc/expr.cc:8736
0x15f2418 store_expr(tree_node*, rtx_def*, int, bool, bool)
        ../../gccrs/gcc/expr.cc:6087
0x15f0b6c expand_assignment(tree_node*, tree_node*, bool)
        ../../gccrs/gcc/expr.cc:5819
0x142e364 expand_call_stmt
        ../../gccrs/gcc/cfgexpand.cc:2829
0x1431fb8 expand_gimple_stmt_1
        ../../gccrs/gcc/cfgexpand.cc:3864
0x14325e6 expand_gimple_stmt
        ../../gccrs/gcc/cfgexpand.cc:4028
0x143ae02 expand_gimple_basic_block
        ../../gccrs/gcc/cfgexpand.cc:6069
0x143d424 execute
        ../../gccrs/gcc/cfgexpand.cc:6795

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• What version of Rust GCC were you using, git sha if possible. cd39861da5e1113207193bb8b3e6fb3dde92895f