MIR inliner doesn't support return place used as an index

[tmiasko]

#![feature(box_syntax)]

#[inline(always)]
pub fn f(a: usize, b: &mut usize, c: &[usize]) -> usize {
    let x = a + a;
    *b = c[x];
    x
}

pub fn g(a: usize, b: &mut usize, c: &[usize]) -> usize {
    f(a, b, c)
}

pub fn h(a: usize, b: &mut usize, c: &[usize]) -> Box<usize> {
    box f(a, b, c)
}

$ rustc a.rs --crate-type=lib -O -Zmir-opt-level=3
thread '<unnamed>' panicked at 'assertion failed: `(left != right)`
  left: `Index(_0)`,
 right: `Index(_0)`', compiler/rustc_mir_transform/src/inline.rs:1035:13

[tmiasko]

Fixed in #106850.