Fix updating of indexes containing escaped characters

[antonivanopoulos]

There are a number of different mechanisms with String#sub that pertain to the matching of backreferences and capture groups when using either the String or Hash type args for the replacement arg.

If replacement is a String that looks like a pattern's capture group but is actually not a pattern capture group e.g. "'", then it will have to be preceded by two backslashes like so "\'".

When an index contains unescaped characters, those are being incorrectly interpreted as capture groups. Using the block version of #sub avoids this.

For example, here's the behaviour we see with an index containing special characters that need escaping.

Existing index:

# Indexes
# 
# index_xyz   (regexp_replace((some_column)::text, '[[:space:]]|\+61|^[0]'::text, ''::text, 'g'::text))

Updated index:

# Indexes
# 
# index_xyz   (regexp_replace((some_column)::text, '[[:space:]]|61|^[0]'::text, ''::text, 'g'::text))

This becomes a problem given that the issue is in the Updater itself; we get stuck in a loop where annotation changes are always being detected, so a CI step with --frozen will always fail.

[drwl]

@antonivanopoulos thanks for finding this bug and submitting this fix. A really interesting difference in behavior between the two modes. I was able to reproduce it myself, for anyone future viewer that is interested:

file_content = <<~FILE
  # An Annotation
  class User < ApplicationRecord
  end
FILE

current_annotations = <<~CURR
  # An Annotation
CURR

new_annotations = <<~ANNOTATIONS
  #  index_rails_02e851e3b8  (another_column) WHERE value IS LIKE '\\\\%'
  #
ANNOTATIONS

puts file_content.sub(current_annotations, new_annotations)
# =>
# #  index_rails_02e851e3b8  (another_column) WHERE value IS LIKE '\%'
# #
# class User < ApplicationRecord
# end

puts file_content.sub(current_annotations) { new_annotations }
# =>
# #  index_rails_02e851e3b8  (another_column) WHERE value IS LIKE '\\%'
# #
# class User < ApplicationRecord
# end
# => nil

[drwl]

Also apologies for delay in review. I have more time now to dedicate back to maintaining this gem.

[antonivanopoulos]

No problem at all, thanks for taking a look 😄