fix(encode): Correct encoding for key with mixed quotes

Author: epage

crates/toml_edit/src/encode.rs

@@ -418,7 +418,10 @@ fn infer_style(
     match (style, literal) {
         (Some(style), Some(literal)) => (style, literal),
         (None, Some(literal)) => (infer_all_style(value).0, literal),
-        (Some(style), None) => (style, infer_all_style(value).1),
+        (Some(style), None) => {
+            let literal = !value.contains('\'') && (value.contains('"') | value.contains('\\'));
+            (style, literal)
+        }
         (None, None) => infer_all_style(value),
     }
 }

crates/toml_edit/tests/testsuite/parse.rs

@@ -1834,12 +1834,10 @@ fn key_value_roundtrip() {
         r#""squoted 'content' squoted""#,
         str![[r#""squoted 'content' squoted""#]],
     );
-    /*
     assert_key_value_roundtrip(
         r#""mixed quoted \"start\" 'end'' mixed quote""#,
-        str![[r#""squoted 'content' squoted""#]],
+        str![[r#""mixed quoted /"start/" 'end'' mixed quote""#]],
     );
-    */
 }
 
 #[track_caller]