fix(parser): allow comments between a bare return and its terminator

[smn]

Problem

A valueless return followed by a comment before the block terminator (elseif / else / end / until) fails to parse:

local function f(method)
  if method == "GET" then
    return
  -- handle other methods
  elseif method == "POST" then
    return
  end
end

Parse Error: Expected expression

Comments are whitespace in Lua, so the return here is simply a bare (valueless) return and the branch continues normally. Reference Lua 5.3 accepts this, and it's a common idiom (then return -- note \n elseif ...).

Root cause

Lua.Parser.parse_return/1 peeked at the raw next token to decide whether the return was valueless. A comment token is not one of the terminators (end/else/elseif/until), nor EOF/;, so it fell through to parse_expr_list, which then choked on the comment → "Expected expression".

Fix

Peek past comment tokens (via the existing skip_comments/1) when detecting the terminator. The comment tokens are left in the stream so the block parser still collects them as orphaned/trailing comments — no comment metadata is lost.

case peek(skip_comments(rest)) do

The semicolon branch consumes past comments as well, so return -- note followed by ; is handled too.

Tests

Added a regression test in test/lua/parser/statement_test.exs covering a bare return with a comment before elseif/else/end — fails before, passes after.

• mix test test/lua/parser/ — all green
• mix test (full suite) — all green

🤖 Generated with Claude Code

[davydog187]

Thanks!

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