fix: avoid leaking wrapper space from doc comment code block formatting

src/lib.rs

@@ -387,6 +387,12 @@ fn format_code_block(
     let block_len = formatted
         .snippet
         .rfind('}')
+        // trim whitespace when using `fn_single_line=true`
+        .map(|i| {
+            formatted.snippet[..i]
+                .strip_suffix(char::is_whitespace)
+                .map_or(i, str::len)
+        })
         .unwrap_or_else(|| formatted.snippet.len());
 
     // It's possible that `block_len < FN_MAIN_PREFIX.len()`. This can happen if the code block was

tests/target/issue-6832.rs

@@ -0,0 +1,12 @@
+// rustfmt-format_code_in_doc_comments: true
+// rustfmt-fn_single_line: true
+
+/// ```rust
+/// let font = String::from("hello");
+/// ```
+fn ascii_string() {}
+
+/// ```rust
+/// let font = String::from("hello 👋😁");
+/// ```
+fn unicode_chars() {}