From 134dc0bcaf60ac54ae0b6d9f154fb158bf734549 Mon Sep 17 00:00:00 2001
From: Jacob Nevins <jacobn@chiark.greenend.org.uk>
Date: Sun, 21 Apr 2019 12:54:39 +0100
Subject: [PATCH] Avoid using _vsnprintf on MinGW.

We went to the trouble of getting standard C99 format strings with
__USE_MINGW_ANSI_STDIO, but then used _vsnprintf, which bypasses them
and implements the non-standard Microsoft format strings, leading to
incorrect behaviour.
Ubuntu 14.04's mingw-w64 at least defines a vsnprintf() in all
circumstances, so we should use it.
---
 utils.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/utils.c b/utils.c
index 17f67587..9824110e 100644
--- a/utils.c
+++ b/utils.c
@@ -308,7 +308,10 @@ int string_length_for_printf(size_t s)
 #endif
 
 /* Also lack of vsnprintf before VS2015 */
-#if defined _WINDOWS && !defined __WINE__ && _MSC_VER < 1900
+#if defined _WINDOWS && \
+    !defined __MINGW32__ && \
+    !defined __WINE__ && \
+    _MSC_VER < 1900
 #define vsnprintf _vsnprintf
 #endif