fixed minor memory leaks of per-state data in teco_machine_main_t

* These were leaked e.g. in case of end-of-macro errors,
  but also in case of syntax highlighting (teco_lexer_style()).
  I considered to solve this by overwriting more of the end_of_macro_cb,
  but it didn't turn out to be trivial always.
* Considering that the union in teco_machine_main_t saved only 3 machine words
  of memory, I decided to sacrifice those for more robust memory management.
* teco_machine_qregspec_t cannot be directly embedded into teco_machine_main_t
  due to recursive dependencies with teco_machine_stringbuilding_t.
  It could now and should perhaps be allocated only once in teco_machine_main_init(),
  but it would require more refactoring.

1 files changed, 12 insertions, 10 deletions

diff --git a/src/parser.h b/src/parser.h
index 36a0302..a1583d2 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -514,17 +514,19 @@ struct teco_machine_main_t {
 	/*
 	 * teco_state_t-dependent state.
 	 *
-	 * Some of these cannot be used concurrently and are therefore
-	 * grouped into unions.
-	 * We could further optimize memory usage by dynamically allocating
-	 * some of these structures on demand.
+	 * Some cannot theoretically be used at the same time
+	 * but it's hard to prevent memory leaks if putting them into
+	 * a common union.
 	 */
-	teco_machine_expectstring_t		expectstring;
-	union {
-		teco_string_t			goto_label;
-		teco_machine_qregspec_t		*expectqreg;
-		teco_machine_scintilla_t	scintilla;
-	};
+	teco_machine_expectstring_t	expectstring;
+	/**
+	 * State machine for parsing Q-reg specifications.
+	 * This could theoretically be inlined, but it would introduce
+	 * a recursive dependency between qreg.h and parser.h.
+	 */
+	teco_machine_qregspec_t		*expectqreg;
+	teco_string_t			goto_label;
+	teco_machine_scintilla_t	scintilla;
 };
 
 typedef struct teco_machine_main_flags_t teco_machine_main_flags_t;