gccrs does not check if something is assignable

Summary

gccrs does not check if something is assignable, and gccrs accepts many un-assignable expressions.

Reproducer

I tried this code:

fn main() -> i32 {
    let mut x = 42;
    x + 1 = 2;

    x
}

Does the code make use of any (1.49) nightly feature ?

• Nightly

Godbolt link

No response

Actual behavior

The current behavior is that gccrs accepts this kind of semantically invalid code and even successfully generates machine code for them (in this case, gccrs generates code to make the function return 42).

Expected behavior

I expected to see an error thrown like rustc does:

error[E0070]: invalid left-hand side of assignment
 --> test1.rs:3:11
  |
3 |     x + 1 = 2;
  |     ----- ^
  |     |
  |     cannot assign to this expression

GCC Version

fa93e280ed1c11d9775cb9c3211e13853d39c51c

Start by compiling the reproducer with gccrs and compare its result with rustc's E0070 diagnostic for x + 1 = 2. Trace the assignment semantic-checking entry point responsible for accepting the expression; done means gccrs rejects unassignable left-hand sides and reports an appropriate error without generating machine code.