Our parse tree differs wrt to block trailing expressions

Some examples:

fn main() {
    S {..}  = ();
    || {  } = ();
    break {  } = ();
}

we get the following diagnostics in rustc

error[E0070]: invalid left-hand side of assignment
 --> src/main.rs:4:13
  |
4 |     || {  } = ();
  |        ---- ^
  |        |
  |        cannot assign to this expression

error[E0070]: invalid left-hand side of assignment
 --> src/main.rs:5:16
  |
5 |     break {  } = ();
  |           ---- ^
  |           |
  |           cannot assign to this expression

which clearly show that these are expression statements containing a binary expression each, yet in r-a the second one is considered a statement containing a closure expression and the third a statement containing a break expresson (with a nested binary expression inside each). This is very much wrong and most likely causes issue in other places as well.

Meanwhile in fn func() { let Some(_) = || {Some(1)} else { panic!("h") };} we should error with error: right curly brace }beforeelsein alet...else statement not allowed yet we accept this just fine.

https://github.com/rust-lang/rust-analyzer/issues/16289 might be related to this.

Start by reproducing the Rust examples and comparing rust-analyzer's parse trees and diagnostics with rustc's output. Investigate parsing of block trailing expressions and let-else statements; done means the assignment examples are represented as binary expression statements and the let-else example is rejected as rustc rejects it.