update information about NaN bug (fixed in DP by f96918f0280)

diff --git a/qcsrc/lib/warpzone/mathlib.qc b/qcsrc/lib/warpzone/mathlib.qc
index cf86d97f9cb5e22e6a2123eaf6f7136630cd590e..2b1d00c2cccca49056f80f877d8574a483000cdf 100644 (file)
--- a/qcsrc/lib/warpzone/mathlib.qc
+++ b/qcsrc/lib/warpzone/mathlib.qc
@@ -24,11 +24,12 @@ bool isinf(float e)
 }
 bool isnan(float e)
 {
-       // the sane way to detect NaN is broken because of a compiler bug
-       // (works with constants but breaks when assigned to variables)
-       // use conversion to string instead
-       //float f = e;
-       //return (e != f);
+       // The sane way to detect NaN is this:
+       // float f = e;
+       // return (e != f);
+       // but darkplaces used to be compiled with -ffinite-math-only which broke it.
+       // DP is fixed now but until all clients update (so after 0.8.3) we have to use the following workaround
+       // or they'd have issues when connecting to newer servers.
 
        // Negative NaN ("-nan") is much more common but plain "nan" can be created by negating *some* -nans so we need to check both.
        // DP's QCVM and GMQCC's QCVM behave differently - one needs ftos(-(0.0 / 0.0)), the other ftos(-sqrt(-1)).
@@ -225,7 +226,7 @@ float copysign(float e, float f)
 {
        return fabs(e) * ((f>0) ? 1 : -1);
 }
-/// Always use `isnan` function to compare because `float x = nan(); x == x;` gives true
+
 float nan(string tag)
 {
        return sqrt(-1);