From 4d01b52228df7df564589908db53f43efab1f891 Mon Sep 17 00:00:00 2001
From: Parker Finch <pfinch@panoramaed.com>
Date: Sun, 26 May 2019 14:07:42 -0400
Subject: [PATCH] [Fix #7063] Fix unsafe autocorrect for
 'Style/TernaryParentheses'

This takes the precedence of operators used into account when deciding
to autocorrect. The issue is that if an operator of precedence below
that of the ternary operator (e.g. "or") is used, then the existing
autocorrect can change the semantics by removing parentheses. With
this change, the autocorrect will no longer attempt to make this
correction.
---
 CHANGELOG.md                                  |  4 ++++
 lib/rubocop/cop/style/ternary_parentheses.rb  | 12 ++++++++++-
 .../cop/style/ternary_parentheses_spec.rb     | 21 +++++++++++++++++++
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c9044488c555..ec2f72f3c362 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### Bug fixes
+
+* [#7063](https://github.com/rubocop-hq/rubocop/issues/7063): Fix autocorrect in `Style/TernaryParentheses` cop. ([@parkerfinch][])
+
 ### Changes
 
 * [#5976](https://github.com/rubocop-hq/rubocop/issues/5976): Remove Rails cops. ([@koic][])
diff --git a/lib/rubocop/cop/style/ternary_parentheses.rb b/lib/rubocop/cop/style/ternary_parentheses.rb
index e04b0561a282..6c93257b57b4 100644
--- a/lib/rubocop/cop/style/ternary_parentheses.rb
+++ b/lib/rubocop/cop/style/ternary_parentheses.rb
@@ -149,7 +149,8 @@ def infinite_loop?
 
         def unsafe_autocorrect?(condition)
           condition.children.any? do |child|
-            unparenthesized_method_call?(child)
+            unparenthesized_method_call?(child) ||
+              below_ternary_precedence?(child)
           end
         end
 
@@ -157,6 +158,15 @@ def unparenthesized_method_call?(child)
           method_name(child) =~ /^[a-z]/i && !child.parenthesized?
         end
 
+        def below_ternary_precedence?(child)
+          # Handle English "or", e.g. 'foo or bar ? a : b'
+          (child.or_type? && child.semantic_operator?) ||
+            # Handle English "and", e.g. 'foo and bar ? a : b'
+            (child.and_type? && child.semantic_operator?) ||
+            # Handle English "not", e.g. 'not foo ? a : b'
+            (child.send_type? && child.prefix_not?)
+        end
+
         def_node_matcher :method_name, <<-PATTERN
           {($:defined? (send nil? _) ...)
            (send {_ nil?} $_ _ ...)}
diff --git a/spec/rubocop/cop/style/ternary_parentheses_spec.rb b/spec/rubocop/cop/style/ternary_parentheses_spec.rb
index 0d25371c322c..08cc8a7936ab 100644
--- a/spec/rubocop/cop/style/ternary_parentheses_spec.rb
+++ b/spec/rubocop/cop/style/ternary_parentheses_spec.rb
@@ -110,6 +110,14 @@
       it_behaves_like 'code with offense',
                       'foo = bar && (baz || bar) ? a : b',
                       'foo = (bar && (baz || bar)) ? a : b'
+
+      it_behaves_like 'code with offense',
+                      'foo = bar or baz ? a : b',
+                      'foo = bar or (baz) ? a : b'
+
+      it_behaves_like 'code with offense',
+                      'not bar ? a : b',
+                      'not (bar) ? a : b'
     end
 
     context 'with an assignment condition' do
@@ -168,6 +176,12 @@
 
       it_behaves_like 'code without offense',
                       'foo = bar && (baz || bar) ? a : b'
+
+      it_behaves_like 'code with offense',
+                      'foo = (foo or bar) ? a : b'
+
+      it_behaves_like 'code with offense',
+                      'foo = (not bar) ? a : b'
     end
 
     context 'with an assignment condition' do
@@ -248,6 +262,10 @@
       it_behaves_like 'code with offense',
                       'foo = (bar[:baz]) ? a : b',
                       'foo = bar[:baz] ? a : b'
+
+      it_behaves_like 'code with offense',
+                      'foo = bar or (baz) ? a : b',
+                      'foo = bar or baz ? a : b'
     end
 
     context 'with a complex condition' do
@@ -255,6 +273,9 @@
                       'foo = (bar.baz?) ? a : b',
                       'foo = bar.baz? ? a : b'
 
+      it_behaves_like 'code without offense',
+                      'foo = (baz or bar) ? a : b'
+
       it_behaves_like 'code without offense',
                       'foo = (bar && (baz || bar)) ? a : b'
     end