only match transitional role (x-) that this distinct from other roles

2 files changed, 16 insertions, 4 deletions

diff --git a/lib/asciidoctor/substitutors.rb b/lib/asciidoctor/substitutors.rb
index 2fc5f9d9..af850790 100644
--- a/lib/asciidoctor/substitutors.rb
+++ b/lib/asciidoctor/substitutors.rb
@@ -1020,11 +1020,17 @@ module Substitutors
             next %(#{$1}[#{attrlist}]#{RS * (escape_count - 1)}#{boundary}#{$5}#{boundary})
           elsif $1 == RS
             preceding = %([#{attrlist}])
-          else
-            if boundary == '++' && (attrlist.end_with? 'x-')
+          elsif boundary == '++'
+            if attrlist == 'x-'
+              old_behavior = true
+              attributes = {}
+            elsif attrlist.end_with? ' x-'
               old_behavior = true
-              attrlist = attrlist.slice 0, attrlist.length - 2
+              attributes = parse_quoted_text_attributes attrlist.slice 0, attrlist.length - 3
+            else
+              attributes = parse_quoted_text_attributes attrlist
             end
+          else
             attributes = parse_quoted_text_attributes attrlist
           end
         elsif (escape_count = $3.length) > 0
@@ -1066,7 +1072,7 @@ module Substitutors
 
       if compat_mode
         old_behavior = true
-      elsif attrlist && (attrlist.end_with? 'x-')
+      elsif attrlist && (attrlist == 'x-' || (attrlist.end_with? ' x-'))
         old_behavior = old_behavior_forced = true
       end
 
diff --git a/test/substitutions_test.rb b/test/substitutions_test.rb
index 47a7bf6c..7b57c6d8 100644
--- a/test/substitutions_test.rb
+++ b/test/substitutions_test.rb
@@ -345,6 +345,12 @@ context 'Substitutions' do
     end
 
     # NOTE must use apply_subs because constrained monospaced is handled as a passthrough
+    test 'should ignore role that ends with transitional role on constrained monospace span' do
+      para = block_from_string %([foox-]`leave it alone`)
+      assert_equal '<code class="foox-">leave it alone</code>', para.apply_subs(para.source)
+    end
+
+    # NOTE must use apply_subs because constrained monospaced is handled as a passthrough
     test 'escaped single-line constrained monospace string with forced compat role' do
       para = block_from_string %([x-]#{BACKSLASH}`leave it alone`)
       assert_equal '[x-]`leave it alone`', para.apply_subs(para.source)