Add support for tabs in indentation (#7867)

This commit adds SupportedStyles to Layout/Tab - spaces and tabs. It also renames the cop to to Layout/IndentationStyle, as the old name no longer reflects its purpose. One notable difference is that before the `Layout/Tab` cop was warning on tabs anywhere in the source, but now we're focusing only on tabs used for indentation purposes.
rubocop · Apr 15, 2020 · 6b9510d · 6b9510d
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 ### New features
 
+* [#7867](https://github.com/rubocop-hq/rubocop/pull/7867): Add support for tabs in indentation. ([@DracoAter][])
 * [#7863](https://github.com/rubocop-hq/rubocop/issues/7863): Corrector now accepts nodes in addition to ranges. ([@marcandre][])
 * [#7862](https://github.com/rubocop-hq/rubocop/issues/7862): Corrector now has a `wrap` method. ([@marcandre][])
 * [#7850](https://github.com/rubocop-hq/rubocop/issues/7850): Make it possible to enable/disable pending cops. ([@koic][])
@@ -12,6 +13,10 @@
 * [#7384](https://github.com/rubocop-hq/rubocop/pull/7384): Add new `Style/DisableCopsWithinSourceCodeDirective` cop. ([@egze][])
 * [#7826](https://github.com/rubocop-hq/rubocop/issues/7826): Add new `Layout/SpaceAroundMethodCallOperator` cop. ([@saurabhmaurya15][])
 
+### Changes
+
+* **(Breaking)** Renamed `Layout/Tab` cop to `Layout/IndentationStyle`. ([@DracoAter][])
+
 ### Bug fixes
 
 * [#7871](https://github.com/rubocop-hq/rubocop/pull/7871): Fix an auto-correction bug in `Lint/BooleanSymbol`. ([@knu][])
@@ -4452,3 +4457,4 @@
 [@rafaelfranca]: https://github.com/rafaelfranca
 [@knu]: https://github.com/knu
 [@saurabhmaurya15]: https://github.com/saurabhmaurya15
+[@DracoAter]: https:/github.com/DracoAter
diff --git a/config/default.yml b/config/default.yml
@@ -801,6 +801,22 @@ Layout/IndentationConsistency:
     # A reference to `EnforcedStyle: indented_internal_methods`.
     - https://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html#follow-the-coding-conventions
 
+Layout/IndentationStyle:
+  Description: 'Consistent indentation either with tabs only or spaces only.'
+  StyleGuide: '#spaces-indentation'
+  Enabled: true
+  VersionAdded: '0.49'
+  VersionChanged: '0.82'
+  # By default, the indentation width from Layout/IndentationWidth is used
+  # But it can be overridden by setting this parameter
+  # It is used during auto-correction to determine how many spaces should
+  # replace each tab.
+  IndentationWidth: ~
+  EnforcedStyle: spaces
+  SupportedStyles:
+    - spaces
+    - tabs
+
 Layout/IndentationWidth:
   Description: 'Use 2 spaces for indentation.'
   StyleGuide: '#spaces-indentation'
@@ -1263,18 +1279,6 @@ Layout/SpaceInsideStringInterpolation:
     - space
     - no_space
 
-Layout/Tab:
-  Description: 'No hard tabs.'
-  StyleGuide: '#spaces-indentation'
-  Enabled: true
-  VersionAdded: '0.49'
-  VersionChanged: '0.51'
-  # By default, the indentation width from Layout/IndentationWidth is used
-  # But it can be overridden by setting this parameter
-  # It is used during auto-correction to determine how many spaces should
-  # replace each tab.
-  IndentationWidth: ~
-
 Layout/TrailingEmptyLines:
   Description: 'Checks trailing blank lines and final newline.'
   StyleGuide: '#newline-eof'

diff --git a/lib/rubocop.rb b/lib/rubocop.rb
@@ -235,6 +235,7 @@
 require_relative 'rubocop/cop/layout/heredoc_argument_closing_parenthesis'
 require_relative 'rubocop/cop/layout/heredoc_indentation'
 require_relative 'rubocop/cop/layout/indentation_consistency'
+require_relative 'rubocop/cop/layout/indentation_style'
 require_relative 'rubocop/cop/layout/indentation_width'
 require_relative 'rubocop/cop/layout/initial_indentation'
 require_relative 'rubocop/cop/layout/leading_comment_space'
@@ -278,7 +279,6 @@
 require_relative 'rubocop/cop/layout/space_inside_range_literal'
 require_relative 'rubocop/cop/layout/space_inside_reference_brackets'
 require_relative 'rubocop/cop/layout/space_inside_string_interpolation'
-require_relative 'rubocop/cop/layout/tab'
 require_relative 'rubocop/cop/layout/trailing_empty_lines'
 require_relative 'rubocop/cop/layout/trailing_whitespace'
 

diff --git a/lib/rubocop/config_obsoletion.rb b/lib/rubocop/config_obsoletion.rb
@@ -17,6 +17,7 @@ class ConfigObsoletion
       'Layout/IndentHash' => 'Layout/FirstHashElementIndentation',
       'Layout/IndentHeredoc' => 'Layout/HeredocIndentation',
       'Layout/LeadingBlankLines' => 'Layout/LeadingEmptyLines',
+      'Layout/Tab' => 'Layout/IndentationStyle',
       'Layout/TrailingBlankLines' => 'Layout/TrailingEmptyLines',
       'Lint/DuplicatedKey' => 'Lint/DuplicateHashKey',
       'Lint/EndInMethod' => 'Style/EndBlock',

diff --git a/lib/rubocop/cop/badge.rb b/lib/rubocop/cop/badge.rb
@@ -4,11 +4,11 @@ module RuboCop
   module Cop
     # Identifier of all cops containing a department and cop name.
     #
-    # All cops are identified by their badge. For example, the badge
-    # for `RuboCop::Cop::Layout::Tab` is `Layout/Tab`. Badges can be
-    # parsed as either `Department/CopName` or just `CopName` to allow
-    # for badge references in source files that omit the department
-    # for RuboCop to infer.
+    # All cops are identified by their badge. For example, the badge for
+    # `RuboCop::Cop::Layout::IndentationStyle` is `Layout/IndentationStyle`.
+    # Badges can be parsed as either `Department/CopName` or just `CopName` to
+    # allow for badge references in source files that omit the department for
+    # RuboCop to infer.
     class Badge
       # Error raised when a badge parse fails.
       class InvalidBadge < Error

diff --git a/lib/rubocop/cop/layout/tab.rb → lib/rubocop/cop/layout/indentation_style.rb b/lib/rubocop/cop/layout/tab.rb → lib/rubocop/cop/layout/indentation_style.rb
@@ -5,9 +5,10 @@
 module RuboCop
   module Cop
     module Layout
-      # This cop checks for tabs inside the source code.
+      # This cop checks that the indentation method is consistent.
+      # Either tabs only or spaces only are used for indentation.
       #
-      # @example
+      # @example EnforcedStyle: spaces (default)
       #   # bad
       #   # This example uses a tab to indent bar.
       #   def foo
@@ -20,17 +21,30 @@ module Layout
       #     bar
       #   end
       #
-      class Tab < Cop
+      # @example EnforcedStyle: tabs
+      #   # bad
+      #   # This example uses spaces to indent bar.
+      #   def foo
+      #     bar
+      #   end
+      #
+      #   # good
+      #   # This example uses a tab to indent bar.
+      #   def foo
+      #     bar
+      #   end
+      class IndentationStyle < Cop
         include Alignment
+        include ConfigurableEnforcedStyle
         include RangeHelp
 
-        MSG = 'Tab detected.'
+        MSG = '%<type>s detected in indentation.'
 
         def investigate(processed_source)
           str_ranges = string_literal_ranges(processed_source.ast)
 
           processed_source.lines.each.with_index(1) do |line, lineno|
-            match = line.match(/\t+/)
+            match = find_offence(line)
             next unless match
 
             range = source_range(processed_source.buffer,
@@ -43,13 +57,37 @@ def investigate(processed_source)
         end
 
         def autocorrect(range)
+          if range.source.include?("\t")
+            autocorrect_lambda_for_tabs(range)
+          else
+            autocorrect_lambda_for_spaces(range)
+          end
+        end
+
+        private
+
+        def find_offence(line)
+          if style == :spaces
+            line.match(/\A\s*\t+/)
+          else
+            line.match(/\A\s* +/)
+          end
+        end
+
+        def autocorrect_lambda_for_tabs(range)
           lambda do |corrector|
             spaces = ' ' * configured_indentation_width
             corrector.replace(range, range.source.gsub(/\t/, spaces))
           end
         end
 
-        private
+        def autocorrect_lambda_for_spaces(range)
+          lambda do |corrector|
+            corrector.replace(range, range.source.gsub(/\A\s+/) do |match|
+              "\t" * (match.size / configured_indentation_width)
+            end)
+          end
+        end
 
         def in_string_literal?(ranges, tabs_range)
           ranges.any? { |range| range.contains?(tabs_range) }
@@ -69,6 +107,10 @@ def string_literal_ranges(ast)
             end
           end
         end
+
+        def message(_node)
+          format(MSG, type: style == :spaces ? 'Tab' : 'Space')
+        end
       end
     end
   end

diff --git a/lib/rubocop/cop/layout/line_length.rb b/lib/rubocop/cop/layout/line_length.rb
@@ -8,7 +8,7 @@ module Layout
       # This cop checks the length of lines in the source code.
       # The maximum length is configurable.
       # The tab size is configured in the `IndentationWidth`
-      # of the `Layout/Tab` cop.
+      # of the `Layout/IndentationStyle` cop.
       # It also ignores a shebang line by default.
       #
       # This cop has some autocorrection capabilities.

diff --git a/lib/rubocop/cop/mixin/line_length_help.rb b/lib/rubocop/cop/mixin/line_length_help.rb
@@ -63,7 +63,7 @@ def indentation_difference(line)
       end
 
       def tab_indentation_width
-        config.for_cop('Layout/Tab')['IndentationWidth']
+        config.for_cop('Layout/IndentationStyle')['IndentationWidth']
       end
 
       def uri_regexp

diff --git a/lib/rubocop/cop/mixin/statement_modifier.rb b/lib/rubocop/cop/mixin/statement_modifier.rb
@@ -58,12 +58,13 @@ def max_line_length
       end
 
       def indentation_multiplier
-        return 1 if config.for_cop('Layout/Tab')['Enabled']
+        return 1 if config.for_cop('Layout/IndentationStyle')['Enabled']
 
         default_configuration = RuboCop::ConfigLoader.default_configuration
-        config.for_cop('Layout/Tab')['IndentationWidth'] ||
+        config.for_cop('Layout/IndentationStyle')['IndentationWidth'] ||
           config.for_cop('Layout/IndentationWidth')['Width'] ||
-          default_configuration.for_cop('Layout/Tab')['IndentationWidth'] ||
+          default_configuration
+            .for_cop('Layout/IndentationStyle')['IndentationWidth'] ||
           default_configuration.for_cop('Layout/IndentationWidth')['Width']
       end
     end

diff --git a/lib/rubocop/cop/style/if_unless_modifier.rb b/lib/rubocop/cop/style/if_unless_modifier.rb
@@ -9,7 +9,7 @@ module Style
       #
       # The maximum line length is configured in the `Layout/LineLength`
       # cop. The tab size is configured in the `IndentationWidth` of the
-      # `Layout/Tab` cop.
+      # `Layout/IndentationStyle` cop.
       #
       # @example
       #   # bad

diff --git a/manual/cops.md b/manual/cops.md
@@ -128,6 +128,7 @@ In the following section you find all available cops:
 * [Layout/HeredocArgumentClosingParenthesis](cops_layout.md#layoutheredocargumentclosingparenthesis)
 * [Layout/HeredocIndentation](cops_layout.md#layoutheredocindentation)
 * [Layout/IndentationConsistency](cops_layout.md#layoutindentationconsistency)
+* [Layout/IndentationStyle](cops_layout.md#layoutindentationstyle)
 * [Layout/IndentationWidth](cops_layout.md#layoutindentationwidth)
 * [Layout/InitialIndentation](cops_layout.md#layoutinitialindentation)
 * [Layout/LeadingCommentSpace](cops_layout.md#layoutleadingcommentspace)
@@ -171,7 +172,6 @@ In the following section you find all available cops:
 * [Layout/SpaceInsideRangeLiteral](cops_layout.md#layoutspaceinsiderangeliteral)
 * [Layout/SpaceInsideReferenceBrackets](cops_layout.md#layoutspaceinsidereferencebrackets)
 * [Layout/SpaceInsideStringInterpolation](cops_layout.md#layoutspaceinsidestringinterpolation)
-* [Layout/Tab](cops_layout.md#layouttab)
 * [Layout/TrailingEmptyLines](cops_layout.md#layouttrailingemptylines)
 * [Layout/TrailingWhitespace](cops_layout.md#layouttrailingwhitespace)
 

diff --git a/manual/cops_layout.md b/manual/cops_layout.md
@@ -2720,6 +2720,59 @@ EnforcedStyle | `normal` | `normal`, `indented_internal_methods`
 * [https://rubystyle.guide#spaces-indentation](https://rubystyle.guide#spaces-indentation)
 * [https://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html#follow-the-coding-conventions](https://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html#follow-the-coding-conventions)
 
+## Layout/IndentationStyle
+
+Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
+--- | --- | --- | --- | ---
+Enabled | Yes | Yes  | 0.49 | 0.82
+
+This cop checks that the indentation method is consistent.
+Either tabs only or spaces only are used for indentation.
+
+### Examples
+
+#### EnforcedStyle: spaces (default)
+
+```ruby
+# bad
+# This example uses a tab to indent bar.
+def foo
+  bar
+end
+
+# good
+# This example uses spaces to indent bar.
+def foo
+  bar
+end
+```
+#### EnforcedStyle: tabs
+
+```ruby
+# bad
+# This example uses spaces to indent bar.
+def foo
+  bar
+end
+
+# good
+# This example uses a tab to indent bar.
+def foo
+  bar
+end
+```
+
+### Configurable attributes
+
+Name | Default value | Configurable values
+--- | --- | ---
+IndentationWidth | `<none>` | Integer
+EnforcedStyle | `spaces` | `spaces`, `tabs`
+
+### References
+
+* [https://rubystyle.guide#spaces-indentation](https://rubystyle.guide#spaces-indentation)
+
 ## Layout/IndentationWidth
 
 Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
@@ -2916,7 +2969,7 @@ Enabled | Yes | Yes  | 0.25 | 0.78
 This cop checks the length of lines in the source code.
 The maximum length is configurable.
 The tab size is configured in the `IndentationWidth`
-of the `Layout/Tab` cop.
+of the `Layout/IndentationStyle` cop.
 It also ignores a shebang line by default.
 
 This cop has some autocorrection capabilities.
@@ -4873,40 +4926,6 @@ EnforcedStyle | `no_space` | `space`, `no_space`
 
 * [https://rubystyle.guide#string-interpolation](https://rubystyle.guide#string-interpolation)
 
-## Layout/Tab
-
-Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
---- | --- | --- | --- | ---
-Enabled | Yes | Yes  | 0.49 | 0.51
-
-This cop checks for tabs inside the source code.
-
-### Examples
-
-```ruby
-# bad
-# This example uses a tab to indent bar.
-def foo
-  bar
-end
-
-# good
-# This example uses spaces to indent bar.
-def foo
-  bar
-end
-```
-
-### Configurable attributes
-
-Name | Default value | Configurable values
---- | --- | ---
-IndentationWidth | `<none>` | Integer
-
-### References
-
-* [https://rubystyle.guide#spaces-indentation](https://rubystyle.guide#spaces-indentation)
-
 ## Layout/TrailingEmptyLines
 
 Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged

diff --git a/manual/cops_style.md b/manual/cops_style.md
@@ -2925,7 +2925,7 @@ written as modifier `if`/`unless`. The cop also checks for modifier
 
 The maximum line length is configured in the `Layout/LineLength`
 cop. The tab size is configured in the `IndentationWidth` of the
-`Layout/Tab` cop.
+`Layout/IndentationStyle` cop.
 
 ### Examples