We've never been using those 'expected' tokens captured during
parsing, which is lame because they contain useful information!
This is much better than merely showing our infamous
"Try removing it!"
Note that the formatter rewrite parens-block sequences as curly-block
sequences anyway. Albeit weird looking syntax, they are valid
nonetheless.
I also clarified a bit the hints and description of the
'illegal::return' error as it would mistakenly say 'function' instead
of 'block'.
- do not erase sequences if the sole expression is an assignment
- emit parse error if an assignment is assigned to an assignment
- do not allow assignments in logical op chains
This has been bothering me and the more I thought of it the more I
disliked the idea of a warning. The rationale being that in this very
context, there's absolutely no ambiguity. So it is only frustrating
that the parser is even able to make the exact suggestion of what
should be fixed, but still fails.
I can imagine it is going to be very common for people to type:
```
trace "foo"
```
...yet terribly frustrating if they have to remember each time that
this should actually be a string. Because of the `trace`, `todo` and
`error` keywords, we know exactly the surrounding context and what to
expect here. So we can work it nicely.
However, the formatter will re-format it to:
```
trace @"foo"
```
Just for the sake of remaining consistent with the type-system. This
way, we still only manipulate `String` in the AST, but we conveniently
parse a double-quote utf-8 literal when coupled with one of the
specific keywords.
I believe that's the best of both worlds.
With pretty parse errors on failures. The type-checker was already
implemented for those, so it now only requires some work in the code
generation.
Fixes#297.
KtorZ