Check compiler for c99 declarations after code.

The sntrup761 reference code contains c99-style declarations after code
so don't try to build that if the compiler doesn't support it.

1 files changed, 3 insertions, 3 deletions

diff --git a/defines.h b/defines.h
index 7fff562c..857abb8b 100644
--- a/defines.h
+++ b/defines.h
@@ -901,10 +901,10 @@ struct winsize {
 #endif
 
 /*
- * sntrup761 uses variable length arrays, only enable if the compiler
- * supports them.
+ * sntrup761 uses variable length arrays and c99-style declarations after code,
+ * so only enable if the compiler supports them.
  */
-#ifdef VARIABLE_LENGTH_ARRAYS
+#if defined(VARIABLE_LENGTH_ARRAYS) && defined(VARIABLE_DECLARATION_AFTER_CODE)
 # define USE_SNTRUP761X25519 1
 #endif
 #endif /* _DEFINES_H */