bump rubocop version to 0.68.0 to support ruby 2.6

this changes upgrades to the earliest version of rubocop
supporting ruby 2.6 while also choosing a version that fixes
a breaking 0.60.0 change to revert psych version change.

namespace changes were made on multiple cops to support
the new rubocop version requirements as well as the change to
move performance cops out of the rubocop gem in to
rubocop-performance.

the Layout/IndentFirstParameter cop is currently broken but a
rubocop version upgrade will fix that. the FreezeConstants cop
also required a fix to handle nil types.

refs DE-289

test plan:
- ensure rubocop runs completely

Change-Id: I0ca68f426e287b5a973b96a4ae0e975f1cbc0240
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/248786
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
QA-Review: Kyle Rosenbaum <krosenbaum@instructure.com>
Product-Review: Kyle Rosenbaum <krosenbaum@instructure.com>
Reviewed-by: Ryan Norton <rnorton@instructure.com>

.rubocop.yml

@@ -1,5 +1,6 @@
 require:
   - rubocop-rspec
+  - rubocop-performance
   # this odd relative path is so that rubocop works when run without "bundle
   # exec", such as from most editors/IDEs.
   - ./gems/rubocop-canvas/lib/rubocop_canvas
@@ -26,7 +27,7 @@ Layout/EmptyLinesAroundMethodBody:
   Enabled: false
 Layout/EmptyLinesAroundModuleBody:
   Enabled: false
-Layout/IndentHash:
+Layout/IndentFirstHashElement:
   Enabled: false
 Layout/IndentationConsistency:
   Enabled: false
@@ -93,7 +94,9 @@ Style/DoubleNegation:
   Enabled: false
 Style/TrailingCommaInArguments:
   Enabled: false
-Style/TrailingCommaInLiteral:
+Style/TrailingCommaInArrayLiteral:
+  Enabled: false
+Style/TrailingCommaInHashLiteral:
   Enabled: false
 Style/MethodCallWithoutArgsParentheses:
   Enabled: false
@@ -194,7 +197,7 @@ Lint/UselessAssignment:
   Severity: convention
 Lint/Debugger:
   Severity: error
-Lint/EndAlignment:
+Layout/EndAlignment:
   EnforcedStyleAlignWith: variable
   Severity: convention
 
@@ -212,7 +215,7 @@ Style/RescueModifier:
   Severity: warning
 Layout/MultilineMethodCallIndentation:
   EnforcedStyle: indented
-Layout/IndentArray:
+Layout/IndentFirstArrayElement:
   EnforcedStyle: consistent
 
 # these don't make sense pre-Rails 4
@@ -278,3 +281,7 @@ Specs/EnsureSpecExtension:
   Enabled: true
   Exclude:
     - spec/shared_examples/**/*
+
+# this cops is crashing; https://github.com/rubocop-hq/rubocop/issues/6992
+Layout/IndentFirstParameter:
+  Enabled: false

Gemfile.d/.rubocop.yml

@@ -2,7 +2,7 @@ inherit_from: ../.rubocop.yml
 
 Metrics/LineLength:
   Enabled: false
-Style/IndentationConsistency:
+Layout/IndentationConsistency:
   Enabled: false
 Metrics/MethodLength:
   Enabled: false

Gemfile.d/test.rb

@@ -38,9 +38,10 @@ group :test do
   gem 'shoulda-matchers', '4.3.0'
 
   gem 'rubocop-canvas', require: false, path: 'gems/rubocop-canvas'
-    gem 'rubocop', '0.52.1', require: false
+    gem 'rubocop', '0.68.0', require: false
       gem 'rainbow', '3.0.0', require: false
-  gem 'rubocop-rspec', '1.22.2', require: false
+  gem 'rubocop-rspec', '1.33.0', require: false
+  gem 'rubocop-performance', '1.3.0', require: false
 
   gem 'once-ler', '0.1.4'
   gem 'sauce_whisk', '0.2.2'

db/migrate/.rubocop.yml

@@ -2,7 +2,7 @@ inherit_from: ../../.rubocop.yml
 
 Metrics/LineLength:
   Enabled: false
-Style/IndentationConsistency:
+Layout/IndentationConsistency:
   Enabled: false
 Metrics/MethodLength:
   Enabled: false

gems/rubocop-canvas/lib/rubocop_canvas/cops/lint/freeze_constants.rb

@@ -47,7 +47,7 @@ module RuboCop
 
         def target_isnt_structure_or_string(node)
           target = node.children.first
-          ![:hash, :array, :string].include?(target.type)
+          ![:hash, :array, :string].include?(target&.type)
         end
 
         def check_children(node, safe_at_next_level)

gems/rubocop-canvas/rubocop-canvas.gemspec

@@ -14,7 +14,7 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
-  spec.add_runtime_dependency "rubocop", "~> 0.52.0"
+  spec.add_runtime_dependency "rubocop", "~> 0.68.0"
   spec.add_runtime_dependency "jira_ref_parser", "1.0.1"
   spec.add_development_dependency "bundler", "~> 1.7"
   spec.add_development_dependency "pry", "~> 0.10.1"