Inline ParserDiagnostic module

Follow #8395 (comment).

This PR does a refactoring to inline `ParserDiagnostic` module.
It seems that it is simpler and easier to maintain if it is implemented
by each cop rather than mix-in the module.

I don't think `ParserDiagnostic` module is used outside of RuboCop core,
at least not in the RuboCop HQ products.
On the other hand, I added it to the changelog just in case for 3rd party gems.

CHANGELOG.md

@@ -50,6 +50,7 @@
 * [#8276](https://github.com/rubocop-hq/rubocop/issues/8276): Cop `Metrics/CyclomaticComplexity` not longer counts `&.` when repeated on the same variable. ([@marcandre][])
 * [#8204](https://github.com/rubocop-hq/rubocop/pull/8204): **(Breaking)** Cop `Metrics/PerceivedComplexity` now counts `else` in `case` statements, `&.`, `||=`, `&&=` and blocks known to iterate. Default bumped from 7 to 8. Consider using `rubocop -a --disable-uncorrectable` to ease transition. ([@marcandre][])
 * [#8416](https://github.com/rubocop-hq/rubocop/issues/8416): Cop `Lint/InterpolationCheck` marked as unsafe. ([@marcandre][])
+* [#8442](https://github.com/rubocop-hq/rubocop/pull/8442): Remove `RuboCop::Cop::ParserDiagnostic` mixin module. ([@koic][])
 
 ## 0.88.0 (2020-07-13)
 

lib/rubocop.rb

@@ -95,7 +95,6 @@
 require_relative 'rubocop/cop/mixin/on_normal_if_unless'
 require_relative 'rubocop/cop/mixin/ordered_gem_node'
 require_relative 'rubocop/cop/mixin/parentheses'
-require_relative 'rubocop/cop/mixin/parser_diagnostic'
 require_relative 'rubocop/cop/mixin/percent_array'
 require_relative 'rubocop/cop/mixin/percent_literal'
 require_relative 'rubocop/cop/mixin/preceding_following_alignment'

lib/rubocop/cop/lint/ambiguous_operator.rb

@@ -21,7 +21,6 @@ module Lint
       #   # With parentheses, there's no ambiguity.
       #   do_something(*some_array)
       class AmbiguousOperator < Base
-        include ParserDiagnostic
         extend AutoCorrector
 
         AMBIGUITIES = {
@@ -39,16 +38,23 @@ class AmbiguousOperator < Base
                      'a whitespace to the right of the `%<operator>s` if it ' \
                      'should be a %<possible>s.'
 
-        private
+        def on_new_investigation
+          processed_source.diagnostics.each do |diagnostic|
+            next unless diagnostic.reason == :ambiguous_prefix
 
-        def autocorrect(corrector, node)
-          add_parentheses(node, corrector)
-        end
+            offense_node = find_offense_node_by(diagnostic)
+            message = message(diagnostic)
 
-        def relevant_diagnostic?(diagnostic)
-          diagnostic.reason == :ambiguous_prefix
+            add_offense(
+              diagnostic.location, message: message, severity: diagnostic.level
+            ) do |corrector|
+              add_parentheses(offense_node, corrector)
+            end
+          end
         end
 
+        private
+
         def find_offense_node_by(diagnostic)
           ast = processed_source.ast
           ast.each_node(:splat, :block_pass, :kwsplat) do |node|
@@ -67,7 +73,7 @@ def find_offense_node_by(diagnostic)
           end
         end
 
-        def alternative_message(diagnostic)
+        def message(diagnostic)
           operator = diagnostic.location.source
           hash = AMBIGUITIES[operator]
           format(MSG_FORMAT, hash)

lib/rubocop/cop/lint/ambiguous_regexp_literal.rb

@@ -22,34 +22,33 @@ module Lint
       #   # With parentheses, there's no ambiguity.
       #   do_something(/pattern/i)
       class AmbiguousRegexpLiteral < Base
-        include ParserDiagnostic
         extend AutoCorrector
 
         MSG = 'Ambiguous regexp literal. Parenthesize the method arguments ' \
               "if it's surely a regexp literal, or add a whitespace to the " \
               'right of the `/` if it should be a division.'
 
-        private
+        def on_new_investigation
+          processed_source.diagnostics.each do |diagnostic|
+            next unless diagnostic.reason == :ambiguous_literal
 
-        def autocorrect(corrector, node)
-          add_parentheses(node, corrector)
-        end
+            offense_node = find_offense_node_by(diagnostic)
 
-        def relevant_diagnostic?(diagnostic)
-          diagnostic.reason == :ambiguous_literal
+            add_offense(diagnostic.location, severity: diagnostic.level) do |corrector|
+              add_parentheses(offense_node, corrector)
+            end
+          end
         end
 
+        private
+
         def find_offense_node_by(diagnostic)
           node = processed_source.ast.each_node(:regexp).find do |regexp_node|
             regexp_node.source_range.begin_pos == diagnostic.location.begin_pos
           end
 
           node.parent
         end
-
-        def alternative_message(_diagnostic)
-          MSG
-        end
       end
     end
   end

lib/rubocop/cop/lint/useless_else_without_rescue.rb

@@ -30,23 +30,14 @@ module Lint
       #     do_something_else
       #   end
       class UselessElseWithoutRescue < Base
-        include ParserDiagnostic
-
         MSG = '`else` without `rescue` is useless.'
 
-        private
-
-        def relevant_diagnostic?(diagnostic)
-          diagnostic.reason == :useless_else
-        end
-
-        def find_offense_node_by(diagnostic)
-          # TODO: When implementing auto-correction, this method should return
-          # an offense node passed as first argument of `add_offense` method.
-        end
+        def on_new_investigation
+          processed_source.diagnostics.each do |diagnostic|
+            next unless diagnostic.reason == :useless_else
 
-        def alternative_message(_diagnostic)
-          MSG
+            add_offense(diagnostic.location, severity: diagnostic.level)
+          end
         end
       end
     end