From fa715ffc775c42cc096f6e7dcff9bf9288e7398c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Sch=C3=BCrmann?= <daschuer@mixxx.org>
Date: Mon, 18 Nov 2024 12:12:24 +0100
Subject: [PATCH] Add a comment about use cases of util_*_infinity()

---
 src/util/fpclassify.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/util/fpclassify.h b/src/util/fpclassify.h
index 4966254b019..8f30a8a63db 100644
--- a/src/util/fpclassify.h
+++ b/src/util/fpclassify.h
@@ -25,5 +25,10 @@ int util_isnan(double x);
 int util_isinf(float x);
 int util_isinf(double x);
 
+// The following functions are only used in testing code.
+// Don't use them in other -ffast-math code to avoid undefined behavior in
+// floating-point arithmetic where the compiler assumes that arguments and
+// results are not NaNs or +-Infs. For checking external librarie's return
+// values use the appropiated function above.
 float util_float_infinity();
 double util_double_infinity();