From 94945a719afc0aa08eaff9aa1e0e2fbf159bf388 Mon Sep 17 00:00:00 2001
From: PatR <rankin@nethack.org>
Date: Tue, 13 Sep 2022 13:59:24 -0700
Subject: [PATCH] onefile: isaac64.c <math.h> vs yn()

isaac64.c includes <math.h>.  yn() is a non-STDC math function in
<math.h> and that conflicts with nethack's yn() macro or vice versa.

If other source files begin using <math.h> this will probably need
to be handled differently.
---
 src/isaac64.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/isaac64.c b/src/isaac64.c
index 76cb769fc..89229d1f6 100644
--- a/src/isaac64.c
+++ b/src/isaac64.c
@@ -7,11 +7,25 @@
  * Changes for NetHack:
  *      include config.h;
  *      skip rest of file if USE_ISAAC64 isn't defined there;
+ *      yn() hackery;
  *      re-do 'inline' handling.
  */
 #include "config.h"
 
 #ifdef USE_ISAAC64
+/*
+ * OSX <math.h> declares yn() in a section labelled
+ * "POSIX/UNIX extensions to the C standard".
+ *
+ * Even when yn() is not a macro, expansion of nethack's yn() macro
+ * would break it.  Matters for 'onefile' lint checking where contents
+ * of hack.h will be visible even though we only include config.h.
+ */
+#ifdef yn
+#undef yn
+#define _isaac64_hide_yn
+#endif
+
 #include <math.h>
 #include <string.h>
 #include "isaac64.h"
@@ -171,6 +185,17 @@ uint64_t isaac64_next_uint(isaac64_ctx *_ctx,uint64_t _n){
   while(((d+_n-1)&ISAAC64_MASK)<d);
   return v;
 }
+
+#ifdef _isaac64_hide_yn
+/* 'onefile' support; restore nethack's yn() macro;
+   this could be made more robust but doesn't need that */
+#ifdef yn
+#undef yn /* in case <math.h> defines yn() as a macro */
+#endif
+#define yn(query) yn_function(query, ynchars, 'n', TRUE)
+#undef _isaac64_hide_yn
+#endif
+
 #endif /* USE_ISAAC64 */
 
 /*isaac64.c*/