Add Style/HeredocIndent

[nobodywasishere]

Enforces that heredoc bodies are indented consistently.

[Sija]

We're testing just the heredoc strings, no need for additional constructs.

Suggested change

	call <<-HEREDOC
	<<-HEREDOC

ditto elsewhere

[nobodywasishere]

The call is needed to make sure the error # ^^^^ is within the heredoc body indentation-wise

[Sija]

That's handled by the ^{} marker.

[nobodywasishere]

What I mean is if the body is indented, the marker can't point to the beginning of the heredoc. This will give a parsing error:

<<-HEREDOC
# ^^^^^^^^ error: Heredoc indent ....
  HEREDOC

[nobodywasishere]

Also we're testing the indent relative to the indent of w/e is on the line where the heredoc start is, not to the indent of the heredoc start itself

[Sija]

Indentation should measured relatively to the Heredoc string.

Suggested change

	correct_indent = line_indent(source, start_location) + indent_by
	unless node.heredoc_indent == correct_indent
	issue_for node, MSG % correct_indent
	end
	unless node.heredoc_indent == indent_by
	issue_for node, MSG % indent_by
	end

[nobodywasishere]

I'm not sure I follow. heredoc_indent is the absolute indent of the heredoc ending identifier (not the relative indent), which is used to strip the extra whitespace from the beginning of the heredoc body. We therefore need to compare it against the desired absolute indent. With that, the heredoc body would always have to be indented by 2 from the beginning of the line.

[Sija]

Desired indent should always be relative, not absolute.

[nobodywasishere]

With the change you're suggesting, a heredoc would have to be indented like this to pass:

class MyClass
  def my_method
    var = <<-HEREDOC
  This is the value for `var`
  HEREDOC
  end
end

With the existing code, it has to be formatted like this:

class MyClass
  def my_method
    var = <<-HEREDOC
      This is the value for `var`
      HEREDOC
  end
end

[Sija]

StringInterpolation#heredoc_indent is counted from the start of the heredoc line, not start of the line, thus I think you're mistaken.

[nobodywasishere]

  call <<-HEREDOC
    body of heredoc
    HEREDOC
^^^^
# This is the heredoc_indent

With the proposed change, the heredoc body fails unless it's indented with two spaces, regardless of the indentation of the line the heredoc is used on:

[Sija]

That's exactly the point. Line indentation shouldn't matter here.

[nobodywasishere]

I completely disagree. That way of formatting heredocs does not match what is used in basically all of the codebases I work with, including this one. Having the body indented two lines while the rest of the code could be 6/8/10 lines indented does not look good.