Fixes #350 by adding missing HEREDOC handling

[vidarh]

Unparser::Emitter::OpAssign was lacking an emit_heredoc_reminders method.

[vidarh]

Sorry, got the issue number wrong. Fixed the title.

[mbj]

@vidarh Your fix appears valid. And I'm going to merge it.

But I'd still love if unparser would only generate heredocs if the AST can only be produced by a heredoc. There is a duality where:

A) Some dstr nodes can be produced by complex string literals, but still string literals.
B) Some dstr nodes can only be produced by heredocs when parsed.

I've yet to find a rule about the signagure in the dstr nodes to differentiate A) and B) to only emit heredoc if its absolutely required.

Also I think heredoc vs not heredoc should be a different AST node, and I hope prism (former YARP), and parser may change this to be discoverable AST level without looking at source locations.

I'll do another OSS cycle this weekend to look deeper into your PR. Thanks so far!

[mbj]

@vidarh I'm coming back to this now, your test is not failing without the code fix:

$ bundle exec unparser --verbose -e 'y += "{42}\n"'
(string)
Original-Source:
y += "{42}\n"
Generated-Source:
y += "{42}\n"
Original-Node:
(op-asgn
  (lvasgn :y) :+
  (str "{42}\n"))
Generated-Node:
(op-asgn
  (lvasgn :y) :+
  (str "{42}\n"))
Success: (string)

Can you tell me a piece of source that shows the bug? (I'm blind, my repro did not interpolate).

[mbj]

I can reproduce it via: #350 (comment), which is odd.

[mbj]

undle exec unparser --verbose -e 'y += "#{42}\n"'
(string)
Original-Source:
y += "#{42}\n"
Generated-Source:
y += <<-HEREDOC
Original-Node:
(op-asgn
  (lvasgn :y) :+
  (dstr
    (begin
      (int 42))
    (str "\n")))
Generated-Node:
#<Parser::SyntaxError: unexpected token tLSHFT>
/home/mutant-dev/.gem/ruby/3.2.2/gems/parser-3.2.2.4/lib/parser/diagnostic/engine.rb:72:in `process'
/home/mutant-dev/.gem/ruby/3.2.2/gems/parser-3.2.2.4/lib/parser/base.rb:286:in `on_error'
/home/mutant-dev/.gem/ruby/3.2.2/gems/racc-1.7.1/lib/racc/parser.rb:265:in `_racc_do_parse_c'
/home/mutant-dev/.gem/ruby/3.2.2/gems/racc-1.7.1/lib/racc/parser.rb:265:in `do_parse'
/home/mutant-dev/.gem/ruby/3.2.2/gems/parser-3.2.2.4/lib/parser/base.rb:190:in `parse'
/home/mutant-dev/devel/unparser/lib/unparser.rb:116:in `block in parse_either'
/home/mutant-dev/devel/unparser/lib/unparser/either.rb:34:in `wrap_error'
/home/mutant-dev/devel/unparser/lib/unparser.rb:115:in `parse_either'
/home/mutant-dev/devel/unparser/lib/unparser/either.rb:115:in `bind'
/home/mutant-dev/devel/unparser/lib/unparser/validation.rb:65:in `from_string'
/home/mutant-dev/devel/unparser/lib/unparser/cli.rb:40:in `validation'
/home/mutant-dev/devel/unparser/lib/unparser/cli.rb:144:in `public_send'
/home/mutant-dev/devel/unparser/lib/unparser/cli.rb:144:in `process_target'
/home/mutant-dev/devel/unparser/lib/unparser/cli.rb:134:in `block in exit_status'
/home/mutant-dev/devel/unparser/lib/unparser/cli.rb:133:in `each'
/home/mutant-dev/devel/unparser/lib/unparser/cli.rb:133:in `exit_status'
/home/mutant-dev/devel/unparser/lib/unparser/cli.rb:64:in `run'
/home/mutant-dev/devel/unparser/bin/unparser:10:in `<top (required)>'
/home/mutant-dev/.gem/ruby/3.2.2/bin/unparser:25:in `load'
/home/mutant-dev/.gem/ruby/3.2.2/bin/unparser:25:in `<top (required)>'
Error: (string)

[mbj]

@vidarh BTW I forgot to make sure test suite ran on CI and your change had a coverage hole, I fixed it in a followup: #353

[mbj]

here was the coverage hole detected by mutant https://github.com/mbj/unparser/actions/runs/6700137747/job/18205557341#step:4:623