From eed88fc61f009c3e397c4dbc6248356978a6031d Mon Sep 17 00:00:00 2001
From: Martin Whitaker <icarus@martin-whitaker.me.uk>
Date: Wed, 15 Apr 2026 16:14:37 +0100
Subject: [PATCH] ivlpp: Ensure def_buf is allocated when calling
 macro_start_args()

macro_start_args() inserts a null string for arg 0 at the start of def_buf.
This allows macro_finish_arg() to calculate the length of the first actual
argument (arg 1). But macro_start_args() relied on def_buf having already
been allocated, which isn't the case when all the macros are pre-defined.

This fixes issue #1323.
---
 ivlpp/lexor.lex | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/ivlpp/lexor.lex b/ivlpp/lexor.lex
index 9094368ac..b20d27119 100644
--- a/ivlpp/lexor.lex
+++ b/ivlpp/lexor.lex
@@ -1599,10 +1599,10 @@ static void macro_start_args(void)
      * entry for arg 0. This will be used by macro_finish_arg() to
      * calculate the buffer location for arg 1.
      */
-    if (def_buf) {
-      def_buf_free = def_buf_size - 1;
-      def_buf[0] = 0;
-    }
+    def_buf_grow_to_fit(1);
+    def_buf_free = def_buf_size - 1;
+    def_buf[0] = 0;
+
     def_argo[0] = 0;
     def_argl[0] = 0;
     def_argc = 1;