error: `var_args!` can only have the `...` spread syntax on the last field.
 --> tests/compile-fail/var_args_spread_middle.rs:4:9
  |
4 |     let var_args!(a, ...b, c) = var_expr!(1, 2.0, "three", false);
  |         ^^^^^^^^^^^^^^^^^^^^^
  |
  = note: this error originates in the macro `$crate::var_args` which comes from the expansion of the macro `var_args` (in Nightly builds, run with -Z macro-backtrace for more info)

warning: unused variable: `a`
 --> tests/compile-fail/var_args_spread_middle.rs:4:19
  |
4 |     let var_args!(a, ...b, c) = var_expr!(1, 2.0, "three", false);
  |                   ^ help: if this is intentional, prefix it with an underscore: `_a`
  |
  = note: `#[warn(unused_variables)]` on by default