From 52bfe3a3c9976427889710ada2f66835ac2b040b Mon Sep 17 00:00:00 2001
From: Tejas Bubane <tejasbubane@gmail.com>
Date: Sun, 24 May 2020 23:57:58 +0530
Subject: [PATCH] Fix infinite loop for `Style/IfUnlessModifier`

Closes #8006 & #8025
---
 CHANGELOG.md                                  |  1 +
 lib/rubocop/cop/mixin/statement_modifier.rb   |  7 ++++---
 .../cop/style/if_unless_modifier_spec.rb      | 20 +++++++++++++++++++
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 12e09889306..7b5e7127145 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,6 +19,7 @@
 * [#8035](https://github.com/rubocop-hq/rubocop/issues/8035): Fix a false positive for `Lint/DeprecatedOpenSSLConstant` when using double quoted string argument. ([@koic][])
 * [#7971](https://github.com/rubocop-hq/rubocop/issues/7971): Fix an issue where `--disable-uncorrectable` would not update uncorrected code with `rubocop:todo`. ([@rrosenblum][])
 * [#8035](https://github.com/rubocop-hq/rubocop/issues/8035): Fix a false positive for `Lint/DeprecatedOpenSSLConstant` when argument is a variable, method, or consntant. ([@koic][])
+* [#8006](https://github.com/rubocop-hq/rubocop/issues/8006): Fix infinite loop for `Style/IfUnlessModifier`. ([@tejasbubane][])
 
 ### Changes
 
diff --git a/lib/rubocop/cop/mixin/statement_modifier.rb b/lib/rubocop/cop/mixin/statement_modifier.rb
index 88ea52a0334..3bea60ebe7c 100644
--- a/lib/rubocop/cop/mixin/statement_modifier.rb
+++ b/lib/rubocop/cop/mixin/statement_modifier.rb
@@ -41,9 +41,10 @@ def modifier_fits_on_single_line?(node)
 
       def length_in_modifier_form(node, cond)
         keyword = node.loc.keyword
-        indentation = keyword.source_line[/^\s*/]
-        line_length("#{indentation}#{node.body.source} #{keyword.source} " \
-                    "#{cond.source}")
+        line_before_condition, = keyword.source_line.split(keyword.source)
+        condition_source = "#{node.body.source} #{keyword.source} #{cond.source}"
+        source = line_before_condition + condition_source
+        line_length(source)
       end
 
       def max_line_length
diff --git a/spec/rubocop/cop/style/if_unless_modifier_spec.rb b/spec/rubocop/cop/style/if_unless_modifier_spec.rb
index 848dbd73554..01f7b2302d8 100644
--- a/spec/rubocop/cop/style/if_unless_modifier_spec.rb
+++ b/spec/rubocop/cop/style/if_unless_modifier_spec.rb
@@ -421,6 +421,26 @@ def f
     expect(corrected).to eq "a = (1 if b)\n"
   end
 
+  context 'when the code before condition pushes inline length over limit' do
+    let(:line_length_config) { { 'Enabled' => true, 'Max' => 100 } }
+
+    it 'does not result in infinite loop with assignment' do
+      expect_no_offenses(<<~RUBY)
+        timespan = if params[:timespan] && POSSIBLE_TIMESPANS.include?(params[:timespan])
+                     params[:timespan].to_sym
+                   end
+      RUBY
+    end
+
+    it 'does not result in infinite loop with any other statement' do
+      expect_no_offenses(<<~RUBY)
+        puts 'ab'; if params[:timespan] && POSSIBLE_TIMESPANS.include?(params[:timespan])
+                     params[:timespan].to_sym
+                   end
+      RUBY
+    end
+  end
+
   it "doesn't break if-end when used as RHS of instance var assignment" do
     corrected = autocorrect_source(<<~RUBY)
       @a = if b