Sema: Don’t use ‘.’ in symbol names of synthesized properties

[eeckstein]

Instead use ‘$’.

[eeckstein]

@swift-ci Please smoke test

[eeckstein]

@jckarter Can you please review this?

[jrose-apple]

This is no good, $ is a valid identifier character.

[jrose-apple]

What's prompting this? Problems with mangling? Problems with the SIL parser?

[jckarter]

$ isn't a valid Swift identifier character. The problem was that the . was leaking into mangled symbol names, and so far we've been trying to keep mangled symbols restricted to the commonly-supported [A-Za-z0-9_$] character set.

[jckarter]

@eeckstein I do think though that it'd be better to mangle unexpected characters like . by mapping them to $ in the mangling rather than changing the AST names. It is useful to synthesize AST nodes with impossible identifiers for names.

[rintaro]

Since #5270
We can

let `$storage` = 1
print(`$storage`)

[jckarter]

I don't think we ever allowed $ as anything other than the first character, though.

[rintaro]

$ in middle of identifiers is allowed even in Swift2.3/3.0, even without backticks.

let foo$storage = 1
print(foo$storage)

[jckarter]

Well, that's arguably a bug we should fix (for future Swift versions) in line with #5270.

[jrose-apple]

:-/ Perhaps. I wish we had a good way to search for that one first.

(We could also do some kind of silly substitution, like $ -> $$, . -> $.)

[jckarter]

Alternatively, we could treat . and all other nonstandard identifier characters as if they were Unicode code units and Punycode them out-of-band. That would also allow us to accept arbitrary strings in a backtick-quoted identifier, if we wanted to…

[eeckstein]

ok, no problem, I'll handle it in the mangling