Ambgious grammar for locals named record/interface/...

[purplesyringa]

I'm trying to make a parser compatible with Teal, and I'm having trouble figuring out how to correctly parse local record ... annotations. Not everything that starts with local record is a record annotation, it could also be a variable, and from a quick test, Teal parses this correctly:

local record -- compiled to Lua as-is
local record <const> = 1 -- <const> is removed

However, there is one scenario where this ambiguity resolution seems to fail:

local record
global interface X end

Both lines are correct individually, but Teal parses this as

local record global
    interface X
    end
-- missing end

...and throws a corresponding error. There are other similar examples, e.g.

local record
func(1) -- syntax error, expected identifier at "func"

Is this intended? I believed that Teal tries to be compatible with Lua, so at least the last snippet would be parsed correctly, since it's pure Lua, but apparently that's not the case.

If this is intended, what are the heuristics for determining whether a given local record ... annotation is a record or a variable?

[hishamhm]

We have made linebreaks relevant in Teal before for dealing with ambiguities. Lua has one such oddity regarding parentheses and function calls, for

local x = f
(expr_returning_function)(args)

We need a ; there in order to get the "obviously desired" semantics (an assignment and a function call). Lua, with its free-form grammar, makes ; usually optional, but that's one exception.

In that case, Teal instead treats the linebreak as relevant. I deemed this difference worth making because things like (x as AnotherType)(...) make this occurrence more common in Teal than in Lua.

Maybe we should apply newline relevance here as well for dealing with this soft-keyword ambiguity.