Retain labels stays a boolean without -r.

org_mode_samples/lesser_element/lesser_block/example/only_k.org

@@ -0,0 +1,3 @@
+#+begin_example foo -k
+bar
+#+end_example

src/compare/diff.rs

@@ -1626,7 +1626,7 @@ fn compare_example_block<'b, 's>(
     }
 
     // Compare retain-labels
-    // retain-labels is t by default, nil if -r is set, or a number if -k is set.
+    // retain-labels is t by default, nil if -r is set, or a number if -k and -r is set.
     let retain_labels = get_property_unquoted_atom(emacs, ":retain-labels")?;
     if let Some(retain_labels) = retain_labels {
         if retain_labels == "t" {
@@ -1652,7 +1652,6 @@ fn compare_example_block<'b, 's>(
                     ));
                 }
             }
-            // foo
         }
     } else {
         match rust.retain_labels {

src/parser/lesser_block.rs

@@ -351,6 +351,7 @@ fn example_switches<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, ExampleSwitc
     let mut retain_labels = RetainLabels::Yes;
     let mut use_labels = true;
     let mut label_format = None;
+    let mut saw_r = false;
     let (remaining, (source, (words, _))) =
         consumed(tuple((separated_list1(space1, switch_word), space0)))(input)?;
 
@@ -366,6 +367,7 @@ fn example_switches<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, ExampleSwitc
                     state = SwitchState::ContinuedLineNumber;
                 }
                 (SwitchState::Normal, "-r") => {
+                    saw_r = true;
                     use_labels = false;
                     match retain_labels {
                         RetainLabels::Yes => {
@@ -378,6 +380,7 @@ fn example_switches<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, ExampleSwitc
                     state = SwitchState::LabelFormat;
                 }
                 (SwitchState::Normal, "-k") => {
+                    use_labels = false;
                     let text_until_flag = input.get_until(word);
                     let character_offset = Into::<&str>::into(text_until_flag).chars().count();
                     let character_offset = CharOffsetInLine::try_from(character_offset)
@@ -426,6 +429,11 @@ fn example_switches<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, ExampleSwitc
         }
     }
 
+    let retain_labels = match retain_labels {
+        RetainLabels::Keep(_) if !saw_r => RetainLabels::Yes,
+        _ => retain_labels,
+    };
+
     Ok((
         remaining,
         ExampleSwitches {